PDF generated using the open source mwlib toolkit. See http://code.pediapress.com/ for more information.PDF generated at: Thu, 08 Dec 2011 01:37:18 UTC

Boron groupAn overview

ContentsArticlesProperties 1

Boron group 1

Elements 14

Boron 14Aluminium 31Gallium 48Indium 59Thallium 68Ununtrium 77

ReferencesArticle Sources and Contributors 83Image Sources, Licenses and Contributors 86

Article LicensesLicense 87

1

Properties

Boron group

Group → 13

↓ Period

2

5B

3

13Al

4

31Ga

5

49In

6

81Tl

7 113Uut

Boron group 2

Legend

Metalloid

Poor metal

Unknown chemical properties

Primordial element

Synthetic

The 5 stable elements of the boron group

The boron group is the series of elements in group 13 (IUPAC style)of the periodic table, comprising boron (B), aluminium (Al), gallium(Ga), indium (In), thallium (Tl), and ununtrium (Uut). The elements inthe boron group are characterized by having three electrons in theirouter energy levels (valence layers).[1] These elements have also beenreferred to as earth metals and as triels.

Boron is classified as a metalloid while the rest, with the possibleexception of ununtrium, are considered poor metals. Ununtrium has notyet been confirmed to be a poor metal and, due to relativistic effects,might not turn out to be one. Boron occurs sparsely, probably becausebombardment by the subatomic particles produced from natural radioactivity disrupts its nuclei. Aluminium occurswidely on earth, and indeed is the third most abundant element in the Earth's crust (8.3%).[2] Gallium is found in theearth with an abundance of 13 ppm. Indium is the 61st most abundant element in the earth's crust, and thallium isfound in moderate amounts throughout the planet. Ununtrium is never found in nature and therefore is termed asynthetic element.

Several group-13 elements have biological roles in the ecosystem. Boron is a trace element in humans and isessential for some plants. Lack of boron can lead to stunted plant growth, while an excess can also cause harm byinhibiting growth. Aluminium has neither a biological role nor significant toxicity and is considered safe. Indium andgallium can stimulate metabolism; gallium is credited with the ability to bind itself to iron proteins. Thallium ishighly toxic, interfering with the function of numerous vital enzymes, and has seen use as a pesticide.[3]

CharacteristicsLike other groups, the members of this family show patterns in their electron configuration, especially the outermostshells, resulting in trends in chemical behavior:

Z Element No. of electrons per shell

5 boron 2, 3

13 aluminium 2, 8, 3

31 gallium 2, 8, 18, 3

49 indium 2, 8, 18, 18, 3

81 thallium 2, 8, 18, 32, 18, 3

113 ununtrium 2, 8, 18, 32, 32, 18, 3

The boron group is notable for trends in the electron configuration, as shown above, and in some of its elements' characteristics. Boron differs from the other group members in its hardness, refractivity and reluctance to participate in metallic bonding. An example of a trend in reactivity is boron's tendency to form reactive compounds with

Boron group 3

hydrogen.[4]

Chemical reactivity

Hydrides

Most of the elements in the boron group show increasing reactivity as the elements get heavier in atomic mass andhigher in atomic number. Boron, the first element in the group, is generally unreactive with many elements except athigh temperatures, although it is capable of forming quite a few compounds with hydrogen, sometimes calledboranes.[5] The simplest borane is diborane, or B2H6.[4] Another example is B10H14.The next group-13 elements, aluminium and gallium, form fewer stable hydrides, although both AlH3 and GaH3exist. Indium, the next element in the group, is not known to form many hydrides, except in complex compoundssuch as H3InP(Cy)3, which is considered to be a phosphine.[6] No stable compound of thallium and hydrogen hasbeen synthesized in any laboratory.

Some common chemical compounds of the boron group[4]

[7]

[8]

[9]

[10]

[11]

Element Oxides Hydrides Fluorides Chlorides Sulfides

Boron (β/g/α)B2O3 B2H6 BF3 BCl3 B2S3

B2O B10H14 BF4-

B6O BH3 B2F4

B5H9 BF

B6H12

B4H10

B6H6−2

B12H12−2

B20H26

Aluminium (γ/δ/η/θ/χ)Al2O3 (α/α`/β/δ/ε/θ/γ) AlH3 AlF3 AlCl3 (α/β/γ) Al2S3

Al2O Al2H6

AlO AlH4

AlH4-

Gallium (α/β/δ/γ/ε) Ga2O3 Ga2H6 GaF3 GaCl3 GaS

GaH4 GaCl2 Ga2+4

GaH3 Ga2Cl4Ga2Cl6

GaCl4−

Ga2Cl7−

Indium In2O3 InH3 InF3 InCl3 (α/β/γ) In2S3

In2O

Boron group 4

Thallium Tl2O3 TlH3 TlF TlCl

Tl2O TlH TlF3 TlCl3TlO2 TlF4

−3 TlCl2

Tl4O3 TlF3−2 Tl2Cl3

Ununtrium Uut2O[12] UutF UutCl

Uut2O3 UutF3

Oxides

All of the boron-group elements are known to form a trivalent oxide, with two atoms of the element bondedcovalently with three atoms of oxygen. These elements show a trend of increasing pH (from acidic to basic).[13]

Boron oxide (B2O3) is slightly acidic, aluminium and gallium oxide (Al2O3 and Ga2O3 respectively) are amphoteric,indium(III) oxide (In2O3) is nearly amphoteric, and thallium(III) oxide (Tl2O3) is a Lewis base because it dissolvesin acids to form salts. Each of these compounds are stable, but thallium oxide decomposes at temperatures higherthan 100°C.

A powdered sample of boron trioxide (B2O3), oneof the oxides of boron

Halides

The elements in group 13 are also capable of forming stablecompounds with the halogens, usually with the formula MX3 (where Mis a boron-group element and X is a halogen.) The only exception tothis is thallium(III) iodide.[14] Fluorine, the first halogen, is able toform stable compounds with every element that has been tested,[15] [16]

and the boron group is no exception. It is even hypothesized thatununtrium could form a compound with fluorine, UutF3, beforespontaneously decaying due to ununtrium's radioactivity. Chlorine alsoforms stable compounds with all of the elements in the boron group,including thallium, and is hypothesized to react with ununtrium. All ofthe elements will react with bromine under the right conditions, as with the other halogens but less vigorously thaneither chlorine or fluorine. Iodine will react with all natural elements in the periodic table except for the noble gases,and is notable for its explosive reaction with aluminium to form 2AlI3.[17] Astatine, the heaviest halogen, has onlyformed a few compounds, due to its radioactvity and short half-life, and no reports of a compound with an At–B,–Al, –Ga, –In, –Tl, or –Uut bond have been seen, although scientists think that it should form salts with metals.[18]

Physical propertiesIt has been noticed that the elements in the boron group have similar physical properties, although most of boron'sare exceptional. For example, all of the elements in the boron group, except for boron itself, are soft. Moreover all ofthe other elements in group 13 are pretty reactive at moderate temperatures, while boron's reactivity only becomescomparable at very high temperatures. One characteristic that all do have in common is having three electrons intheir valence shells. Boron, being a metalloid, is a thermal and electrical insulator at room temperature, but a goodconductor of heat and electricity at high temperatures.[7] Unlike boron, the metals in the group are good conductorsunder normal conditions. This is in accordance with the long-standing generalization that all metals conduct heat andelectricity better than most non-metals.[19]

Boron group 5

Oxidation statesThe inert s-pair effect is significant in the group-13 elements, especially the heavier ones like thallium. This resultsin a variety of oxidation states. In the lighter elements, the +3 state is the most stable, but the +1 state becomes moreprevalent with increasing atomic number, and is the most stable for thallium.[20] Boron is capable of formingcompounds with lower oxidization states, of +1 or +2, and aluminium can do the same.[21] Gallium cannot formcompounds with the oxidation state +2 but can with +1 and +3. Indium is like gallium, but its +1 compounds aremore stable than those of the other elements. The strength of the inert-pair effect is maximal in thallium, which isonly stable in the oxidation state of +1, although the +3 state is seen in some compounds.

IsotopesWith the exception of the synthetic ununtrium, all of the elements of the boron group have stable isotopes. Becauseall their atomic numbers are odd, boron, gallium and thallium have only two stable isotopes, while aluminium andindium are monoisotopic, having only one. 10B and 11B are both stable, as are 27Al, 69Ga and 71Ga, 113In, and 203Tland 205Tl.[22] All of these isotopes are readily found in macroscopic quantities in nature. Group 13 is notable forincluding some of the heaviest stable isotopes ever found; only lead has a heavier stable isotope. In theory, though,all isotopes with an atomic mass greater than 40 are supposed to be unstable to such decay modes as spontaneousfission and alpha decay. Conversely, all isotopes whose atomic masses are less than 40 are theoretically supposed tobe energetically stable to all forms of decay (with the exception of proton decay, which has never been observed).Like all other elements, the group-13 elements have radioactive isotopes, either found in trace quantities in nature orproduced synthetically. The longest-lived of these unstable isotopes is the indium isotope 115In, with its extremelylong half-life of 4.41 × 1014 y. This isotope is relatively important among indium's radioisotopes. The shortest-livedis 7B, with a half-life of a mere 350±50 × 10−24 s, being the boron isotope with the fewest neutrons and a half-lifelong enough to measure. Some radioisotopes have important roles in scientific research; a few are used in theproduction of goods for commercial use or, more rarely, as a component of finished products.[23]

HistoryThe boron group has had many names over the years. According to former conventions it was Group IIIB in theEuropean naming system and Group IIIA in the American. The group has also gained two collective names, "earthmetals" and "triels". The latter name is derived from the Latin prefix tri- ("three") and refers to the three valenceelectrons that all of these elements, without exception, have in their valence shells.[1]

Boron was known to the ancient Egyptians, but only in the mineral borax. The metalloid element was not known inits pure form until 1808, when Humphry Davy was able to extract it by the method of electrolysis. Davy devised anexperiment in which he dissolved a boron-containing compound in water and sent an electric current through it,causing the elements of the compound to separate into their pure states. To produce larger quantities he shifted fromelectrolysis to reduction with sodium. Davy named the element boracium. At the same time two French chemists,Joseph Louis Gay-Lussac and Louis Jacques Thénard, used iron to reduce boric acid. The boron they produced wasoxidized to boron oxide.[24] [25]

Aluminium, like boron, was first known in minerals before it was finally extracted from alum, a common mineral in some areas of the world. Antoine Lavoisier and Humphry Davy had each separately tried to extract it. Although neither succeeded, Davy had given the metal its current name. It was only in 1825 that the Danish scientist Hans Christian Ørsted successfully prepared a rather impure form of the element. Many improvements followed, a significant advance being made just two years later by Friedrich Wöhler, whose slightly modified procedure still yielded an impure product. The first pure sample of aluminium is credited to Henri Etienne Sainte-Claire Deville, who substituted sodium for potassium in the procedure. At that time aluminium was considered precious, and it was displayed next to such metals as gold and silver.[25] [26] The method used today, electrolysis of aluminium oxide

Boron group 6

dissolved in cryolite, was developed by Charles Martin Hall and Paul Héroult in the late 1880s.[25]

The mineral zinc blende, more commonly knownas sphalerite, in which both indium and thallium

were first discovered.

Thallium, the heaviest stable element in the boron group, wasdiscovered by William Crookes and Claude-Auguste Lamy in 1861.Unlike gallium and indium, thallium had not been predicted by DmitriMendeleev. As a result, no one was really looking for it until the 1850swhen Crookes and Lamy were examining residues from sulfuric acidproduction. In the spectra they saw a completely new line, a streak ofdeep green, which Crookes named after the Greek word θαλλός(thallos), referring to a green shoot or twig. Lamy was able to producelarger amounts of the new metal and determined most of its chemicaland physical properties.[27] [28]

Indium is the fourth element of the boron group but was discoveredbefore the third, gallium, and after the fifth, thallium. In 1863Ferdinand Reich and his assistant, Hieronymous Theodor Richter, werelooking in a sample of the mineral zinc blende, also known as sphalerite (ZnS), for the spectroscopic lines of thenewly discovered element thallium. Reich heated the ore in a coil of platinum metal and observed the lines thatappeared in a spectroscope. Instead of the green thallium lines that he expected, he saw a new line of deepindigo-blue. Concluding that it must come from a new element, they named it after the characteristic indigo color ithad produced.[27] [29]

Gallium minerals were not known before August 1875, when the element itself was discovered. It was one of theelements that the inventor of the periodic table, Dimitri Mendeleev, had predicted to exist six years earlier. Whileexamining the spectroscopic lines in zinc blende the French chemist Paul Emile Lecoq de Boisbaudran foundindications of a new element in the ore. In just three months he was able to produce a sample, which he purified bydissolving it in a potassium hydroxide (KOH) solution and sending an electric current through it. The next month hepresented his findings to the French Academy of Sciences, naming the new element after the Greek name for Gaul,modern France.[30] [31]

It can be argued that the last confirmed element in the boron group, ununtrium, was not really "discovered", but"created" or synthesized. The element's synthesis is credited jointly to the Dubna Joint Institute for Nuclear Researchteam in Russia and the Lawrence Livermore National Laboratory in the United States, though it was the Dubna teamwho successfully conducted the experiment in August 2003. Element 113 (ununtrium) was discovered in the decaychain of element 115, or ununpentium, which produced a few precious atoms of ununtrium or "eka-thallium". Theresults were published in January of the following year. Since then around 13 atoms have been synthesized andvarious isotopes characterized.[32]

EtymologyThe name "boron" comes from the Arabic word for the mineral borax,(بورق, boraq) which was known before boronwas ever extracted. The "-on" suffix is thought to have been taken from "carbon"; so the name can regarded as aportmanteau of "borax" and "carbon".[33] Aluminium was named by Humphry Davy in the early 1800s. It is derivedfrom the Greek word alumen, meaning bitter salt, or the Latin alum, the mineral.[34] Gallium is derived from theLatin Gallia, referring to France, the place of its discovery.[35] Indium comes from the Latin word indicum, meaningindigo dye, and refers to the element's prominent indigo spectroscopic line.[36] Thallium, like indium, is named afterthe Greek word for the color of its spectroscopic line: thallos, meaning a green twig or shoot.[37] [38] "Ununtrium" isa temporary name assigned by the IUPAC (see IUPAC nomenclature), derived from the Latin names of the digits inthe number 113.

Boron group 7

Occurrence and abundance

BoronBoron, with its atomic number of 5, is a very light element. Almost never found free in nature, it is very low inabundance, composing only 0.001% (10 ppm)[39] of the Earth's crust. It is known to occur in over a hundred differentminerals and ores, however: the main source is borax, but it is also found in colemanite, boracite, kernite, tusionite,berborite and fluoborite.[40] Major world miners and extractors of boron include the United States, Turkey,Argentina, China, Bolivia and Peru. Turkey is by far the most prominent of these, accounting for around 70% of allboron extraction in the world. The United States is second, most of its yield coming from the state of California.[41]

AluminiumAluminium, in contrast to boron, is the most abundant metal in the Earth's crust, and the third most abundantelement. It composes about 8.2% (82,000 ppm) of the Earth, surpassed only by oxygen and silicon.[39] It is likeboron, however, in that it is uncommon in nature as a free element. This is due to aluminium’s tendency to attractoxygen atoms, forming several aluminium oxides. Aluminium is now known to occur in nearly as many minerals asboron, including garnets, turquoises and beryls, but the main source is the ore bauxite. The world's leading countriesin the extraction of aluminium are Ghana, Surinam, Russia and Indonesia, followed by Australia, Guinea andBrazil.[42]

GalliumGallium is a relatively rare element in the Earth's crust and is not found in as many minerals as its lighterhomologues. Its abundance on the Earth is a mere 0.0018% (18 ppm).[39] Its production is very low compared toother elements, but has increased greatly over the years as extraction methods have improved. Gallium can be foundas a trace in a variety of ores, including bauxite and sphalerite, and in such minerals as diaspore and germanite. Traceamounts have been found in coal as well.[43] The gallium content is greater in a few minerals, including gallite(CuGaS2), but these are too rare to be counted as major sources and make negligible contributions to the world'ssupply.

IndiumIndium is another rare element in the boron group. Even less abundant than gallium at only 0.000005% (0.05ppm),[39] it is the 61st most common element in the earth's crust. Very few indium-containing minerals are known,all of them scarce: an example is indite. Indium is found in several zinc ores, but only in minute quantities; likewisesome copper and lead ores contain traces. As is the case for most other elements found in ores and minerals, theindium extraction process has become more efficient in recent years, ultimately leading to larger yields. Canada isthe world's leader in indium reserves, but both the United States and China have comparable amounts.[44]

Boron group 8

Thallium

A small bundle of fiberglass

Thallium is neither rare nor common in the Earth's crust, but fallssomewhere in the middle. Its abundance is estimated to be 0.00006%(0.6 ppm).[39] Thallium is the 56th most common element in the earth'scrust, more abundant than indium by a sizeable amount. It is found onthe ground in some rocks, in the soil and in clay. Many sulfide ores ofiron, zinc and cobalt contain thallium. In minerals it is found inmoderate quantities: some examples are crookesite (in which it wasfirst discovered), lorandite, routhierite, bukovite, hutchinsonite andsabatierite. There are other minerals that contain small amounts ofthallium, but they are very rare and do not serve as primary sources.Macedonia is a notable thallium extractor and producer.

Ununtrium

Ununtrium is an element that is never found in nature but has beencreated in a laboratory. It is therefore classified as a synthetic elementwith no stable isotopes.

Applications

With the exception of synthetic ununtrium, all the elements in theboron group have numerous uses and applications in the productionand content of many items.Boron has found many industrial applications in recent decades, and new ones are still being found. A commonapplication is in fiberglass.[45] There has been rapid expansion in the market for borosilicate glass; most notableamong its special qualities is a much greater resistance to thermal expansion than regular glass. Anothercommercially expanding use of boron and its derivatives is in ceramics. Several boron compounds, especially theoxides, have unique and valuable properties that have led to their substitution for other materials that are less useful.Boron may be found in pots, vases, plates, and ceramic pan-handles for its insulating properties. The compoundborax is used in bleaches, for both clothes and teeth. The hardness of boron and some of its compounds give it awide array of additional uses. A small part (5%) of the boron produced finds use in agriculture.[45]

Aluminium is a metal with numerous familiar uses in everyday life. It is most often encountered in constructionmaterials, in electrical devices, especially as the conductor in cables, and in tools and vessels for cooking andpreserving food. Aluminium's lack of reactivity with food products makes it particularly useful for canning. Its highaffinity for oxygen makes it a powerful reducing agent. Finely powdered pure aluminium oxidizes rapidly in air,generating a huge amount of heat in the process (burning at about 5500 °F or 3037 °C), leading to applications inwelding and elsewhere that a large amount of heat is needed. Aluminium is a component of alloys used for makinglightweight bodies for aircraft. Cars also sometimes incorporate aluminium in their framework and body, and thereare similar applications in military equipment. Less common uses include components of decorations and someguitars. The element is also sees use in a diverse range of electronics.[46] [47]

Boron group 9

Gallium is one of the chief components of blueLEDs

Gallium and its derivatives have only found applications in recentdecades. Gallium arsenide has been used in semiconductors, inamplifiers, in solar cells (for example in satellites) and in tunnel diodesfor FM transmitter circuits. Gallium alloys are used mostly for dentalpurposes. Gallium ammonium chloride is used for the leads intransistors.[48] A major application of gallium is in LED lighting. Thepure element has been used as a dopant in semiconductors,[49] and hasadditional uses in electronic devices with other elements. Gallium hasthe property of being able to 'wet' glass and porcelain, and thus can beused to make mirrors and other highly reflective objects. Gallium canbe added to alloys of other metals to lower their melting points.

Indium's uses can be divided into four categories: the largest part (70%) of the production is used for coatings,usually combined as indium tin oxide (ITO); a smaller portion (12%) goes into alloys and solders; a similar amountis used in electrical components and in semiconductors; and the final 6% goes to minor applications.[50] Among theitems in which indium may be found are platings, bearings, display devices, heat reflectors, phosphors, and nuclearcontrol rods. Indium tin oxide has found a wide range of applications, including glass coatings, solar collectors,streetlights, electrophosetic displays (EPDs), electroluminescent displays (ELDs), plasma display panels (PDPs),electrochemic displays (ECs), field emission displays (FEDs), sodium lamps, windshield glass and cathode raytubes, making it the single most important indium compound.[51]

Thallium is used in its elemental form more often than the other boron-group elements. Uncompounded thallium isused in low-melting glasses, photoelectric cells, switches, mercury alloys for low-range glass thermometers, andthallium salts. It can be found in lamps and electronics, and is also used in myocardial imaging. The possibility ofusing thallium in semiconductors has been researched, and it is a known catalyst in organic synthesis. Thalliumhydroxide (TlOH) is used mainly in the production of other thallium compounds. Thallium sulfate (Tl2SO4) is anoutstanding vermin-killer, and it is a principal component in some rat and mouse poisons. However, the UnitedStates and some European countries have banned the substance because of its high toxicity to humans. In othercountries, though, the market for the substance is growing. Tl2SO4 is also used in optical systems.[52]

Biological roleNone of the group-13 elements has a major biological role in complex animals, but some are at least associated witha living being. As in other groups, the lighter elements usually have more biological roles than the heavier. Theheaviest ones are toxic, as are the other elements in the same periods. Boron is essential in most plants, whose cellsuse it for such purposes as strengthening cell walls. It is found in humans, certainly as a trace element, but there isongoing debate over its significance in human nutrition. Boron's chemistry does allow it to form complexes withsuch important molecules as carbohydrates, so it is plausible that it could be of greater use in the human body thanpreviously thought. Boron has also been shown to be able to replace iron in some of its functions, particularly in thehealing of wounds.[53] Aluminium has no known biological role in plants or animals. Gallium is not essential for thehuman body, but its relation to iron(III) allows it to become bound to proteins that transport and store iron.[54]

Gallium can also stimulate metabolism. Indium and its heavier homologues have no biological role, although indiumsalts in small doses, like gallium, can stimulate metabolism.[29]

Boron group 10

ToxicityAll of the elements in the boron group can be toxic, given a high enough dose. Some of them are only toxic to plants,some only to animals, and some to both.As an example of boron toxicity, it has been observed to harm barley in concentrations exceeding 20 mM.[55] Thesymptoms of boron toxicity are numerous in plants, complicating research: they include reduced cell division,decreased shoot and root growth, decreased production of leaf chlorophyll, inhibition of photosynthesis, lowering ofstomata conductance, reduced proton extrusion from roots, and deposition of lignin and suborgin.[56]

Aluminium does not present a prominent toxicity hazard in small quantities, but very large doses are slightly toxic.Gallium is not considered toxic, although it may have some minor effects. Indium is not toxic and can be handledwith nearly the same precautions as gallium, but some of its compounds are slightly to moderately toxic.Thallium, unlike gallium and indium, is extremely toxic, and has caused many poisoning deaths. Its most noticeableeffect, apparent even from tiny doses, is hair loss all over the body, but it causes a wide range of other symptoms,disrupting and eventually halting the functions of many organs. The nearly colorless, odorless and tasteless nature ofthallium compounds has led to their use by murderers. The incidence of thallium poisoning, intentional andaccidental, increased when thallium (with its similarly toxic compound, thallium sulfate) was introduced to controlrats and other pests. The use of thallium pesticides has therefore been prohibited since 1975 in many countries,including the USA.Ununtrium is a highly unstable element and decays by emitting radioactive particles. It is, without a doubt, extremelytoxic.[57]

Notes[1] C. Kotz, Treichel, R. Townsend, John, Paul, John (2009). Chemistry and chemical reactivity (http:/ / books. google. com/

books?id=jcn6sgt7RpoC& pg=PA351& dq=main+ group+ elements+ valency#v=onepage& q=main group elements valency& f=false). 2.Belmont, Ca, USA: Thomson Books. p. 351. ISBN 0495387126. . Retrieved July 18, 2011.

[2] "Soviet Aluminium from Clay" (http:/ / books. google. com/ books?id=vPmlBbHCOTIC& pg=PA89& dq=aluminium+abundance#v=onepage& q=aluminium abundance& f=false). The New Scientist (One Shilling Weekly) 8 (191): 89. 1960. . Retrieved2011-06-29.

[3] R. Dobbs, Michael (2009). Clinical neurotoxicology: syndromes, substances, environments (http:/ / books. google. com/books?id=Pmcy24y2HyMC& pg=PA277& dq=thallium+ toxicity#v=onepage& q=thallium toxicity& f=false). Philadelphia, Pa: Saunders.pp. 276–278. ISBN 978-0-323-05260-3. .

[4] Harding, A. Johnson, Janes, Charlie, David, Rob (2002). Elements of the p block (http:/ / books. google. com/books?id=W0HW8wgmQQsC& pg=PA113& dq=boron+ + hydrides#v=onepage& q=boron hydrides& f=false). Cambridge, UK: The OpenUniversity. p. 113. ISBN 0854046909. . Retrieved July 17, 2011.

[5] P. S. Raghavan (1998). Concepts And Problems In Inorganic Chemistry (http:/ / books. google. com/ books?id=pBiS0jc-kWIC& pg=PA43&dq=Boron-hydrogen+ compounds#v=onepage& q=Boron-hydrogen compounds& f=false). New Delhi, India: Discovery Publishing House.p. 43. ISBN 8178414184. . Retrieved July 12, 2011.

[6] Phosphine and phosphido indium hydride complexes and their use in inorganic synthesis – Journal of the Chemical Society, DaltonTransactions (RSC Publishing) (http:/ / pubs. rsc. org/ en/ Content/ ArticleLanding/ 2000/ DT/ a908418e). Pubs.rsc.org (2000-01-27).Retrieved on 2011-05-16.

[7] Downs, Anthony John (1993). Chemistry of aluminium, gallium, indium, and thallium (http:/ / books. google. com/ ?id=v-04Kn758yIC&pg=PA201& dq=chemistry+ of+ aluminium,+ ga#v=onepage& q=chemistry of aluminium, ga& f=false). Chapman and Hall Inc..pp. 197–201. ISBN 9780751401035. .

[8] Daintith, John (2004). Oxford dictionary of chemistry (http:/ / books. google. com/ ?id=jzT-zlKESmsC& pg=PA269& dq=group+ 13+compounds#v=onepage& q=group 13 compounds& f=false). Market House Books. ISBN 9780198609186. .

[9] (Russian)Bleshinsky, S. V.; Abramova, V. F. (1958). Химия индия. Frunze. p. 301.[10] Downs, Anthony John (1993). Chemistry of aluminium, gallium, indium, and thallium (http:/ / books. google. com/ ?id=v-04Kn758yIC&

pg=PA201& dq=chemistry+ of+ aluminium,+ ga#v=onepage& q=chemistry of aluminium, ga& f=false). Chapman and Hall Inc..pp. 195–196. ISBN 9780751401035. .

[11] W. Henderson (2000). Main group chemistry (http:/ / books. google. com/ books?id=twdXz1jfVOsC& printsec=frontcover& dq=main+group+ chemistry#v=onepage& q& f=false). Cambridge, UK: The Royal Society of Chemistry. p. 6. ISBN 0854046178. . Retrieved July 10,2011.

[12] To this date, no ununtrium compounds have been synthesized, and all proposed compounds are entirely theoretical.

Boron group 11

[13] Jellison, Jr., Panek, Bray, Rouse, Jr., G. E., L. W., P. J., G. B. (1977). Trends for the Oxides of the Group 13 Elements J. chem. phys (http:/ /cnx. org/ content/ m32460/ latest/ ?collection=col11124/ latest). pp. 66, 802. Trends for the Oxides of the Group 13 Elements. Retrieved June16, 2011.

[14] W. Henderson (2000). Main group chemistry (http:/ / books. google. com/ books?id=twdXz1jfVOsC& printsec=frontcover& dq=main+group+ chemistry#v=onepage& q& f=false). Cambridge, UK: The Royal Society of Chemistry. p. 60. ISBN 0854046178. . Retrieved July 9,2011.

[15] Young, J. P.; Haire, R. G.; Peterson, J. R.; Ensor, D. D.; Fellow, R. L. (1981). "Chemical Consequences of Radioactive Decay. 2.Spectrophotometric Study of the Ingrowth of Berkelium-249 and Californium-249 Into Halides of Einsteinium-253". Inorganic Chemistry 20(11): 3979–3983. doi:10.1021/ic50225a076.

[16] Except neon and helium, the two noble gases of which no stable compound has been formed.[17] Francis, William (1918). The Chemical Gazette, or Journal of Practical Chemistry (http:/ / books. google. com/

books?id=-KwRAAAAYAAJ& pg=PA269& dq=aluminium+ iodide#v=onepage& q=aluminium iodide& f=false). XVI. Boston, Ma. p. 269. .[18] Roza, Greg (2010). The Halogen Elements: Fluorine, Chlorine, Bromine, Iodine, Astatine (http:/ / books. google. com/

books?id=twdXz1jfVOsC& printsec=frontcover& dq=main+ group+ chemistry#v=onepage& q& f=false). NY, New York, USA: The RozenPublishing Group, Inc.. p. 33. ISBN 9781435835566. . Retrieved July 17, 2011.

[19] E. Girard, James (2010). Criminalistics: Forensic Science, Crime and Terrorism (http:/ / books. google. com/ books?id=JRe7qd5u0yAC&pg=PA221& dq=metals+ conduct+ electricity+ better+ than+ nonmetals#v=onepage& q=metals conduct electricity better than nonmetals&f=false). Jones & Bartlett Learning. p. 221. ISBN 9780763777319. .

[20] W. Henderson (2000). Main group chemistry (http:/ / books. google. com/ books?id=twdXz1jfVOsC& printsec=frontcover& dq=main+group+ chemistry#v=onepage& q& f=false). Cambridge, UK: The Royal Society of Chemistry. p. 57. ISBN 0854046178. . Retrieved July 9,2011.

[21] Barrett, Jack (2001). Structure and bonding (http:/ / books. google. com/ ?id=-zIM6J1gEJkC& printsec=frontcover#v=onepage&q=oxidization strates& f=false). Cambridge, UK: The Royal Society of Chemistry. p. 91. ISBN 085404647X. . Retrieved July 18, 2011.

[22] Aldridge, Simon; Anthony J. Downs, Tony Downs (2011). The Group 13 Metals Aluminium, Gallium, Indium and Thallium: ChemicalPatterns and Peculiarities (http:/ / books. google. com/ ?id=0AazLrNPoMEC& dq=Group+ 13). John Wiley & Sons. p. ii.ISBN 9780470681916. .

[23] Downs, A.J.; I.J. Polmear, M.J. Taylor, P.J. Brothers, K.A. Evans, I.R. Grant, K.B. Starowieyski, J.A. Miller, D.G. Tuck, R.B. Martin, H.Onishi (1993). Chemistry of aluminium, gallium, indium, and thallium (http:/ / books. google. com/ ?id=v-04Kn758yIC& pg=PA117&dq=group+ 13#v=onepage& q=group 13& f=false). Blackie Academic & Professional. pp. 19–24. ISBN 9780751401035. .

[24] Krebs, Robert E. (2006). The History and Use of Our Earth's Chemical Elements: A Reference Guide (http:/ / books. google. com/?id=yb9xTj72vNAC& pg=PA182& dq=history+ of+ gallium#v=onepage& q=history of gallium& f=false). Greenwood Press. p. 176.ISBN 9780313334382. .

[25] Weeks, Mary Elvira (1932). "The discovery of the elements. XII. Other elements isolated with the aid of potassium and sodium: Beryllium,boron, silicon, and aluminium". Journal of Chemical Education 9 (8): 1386. Bibcode 1932JChEd...9.1386W. doi:10.1021/ed009p1386.

[26] Downs, Anthony John (1993). Chemistry of aluminium, gallium, indium, and thallium (http:/ / books. google. com/ ?id=v-04Kn758yIC&printsec=frontcover& dq=aluminium#v=onepage& q& f=false). Chapman and Hall Inc.. p. 15. ISBN 9780751401035. .

[27] Weeks, Mary Elvira (1932). "The discovery of the elements. XIII. Some spectroscopic discoveries". Journal of Chemical Education 9 (8):1413. Bibcode 1932JChEd...9.1413W. doi:10.1021/ed009p1413.

[28] Enghag, Per (2004). Encyclopedia of the elements: technical data, history, processing, applications (http:/ / books. google. com/?id=aff7sEea39EC& printsec=frontcover#v=onepage& q& f=false). p. 71. ISBN 9783527306664. .

[29] Emsley, John (2006). Nature's building blocks: an A-Z guide to the elements (http:/ / books. google. com/ ?id=j-Xu07p3cKwC&pg=PA192& dq=history+ of+ indium#v=onepage& q=history of indium& f=false). Greenwood Press. p. 192. ISBN 9780198503408. .

[30] Emsley, John (2006). Nature's building blocks: an A-Z guide to the elements (http:/ / books. google. com/ ?id=j-Xu07p3cKwC&pg=PA158& dq=history+ of+ gallium#v=onepage& q=history of gallium& f=false). Greenwood Press. pp. 158–159. ISBN 9780198503408. .

[31] Weeks, Mary Elvira (1932). "The discovery of the elements. XV. Some elements predicted by Mendeleeff". Journal of Chemical Education9 (9): 1605–1619. Bibcode 1932JChEd...9.1605W. doi:10.1021/ed009p1605.

[32] Oganessian, Yu. Ts.; Utyonkoy, V.; Lobanov, Yu.; Abdullin, F.; Polyakov, A.; Shirokovsky, I.; Tsyganov, Yu.; Gulbekian, G. et al. (2004)."Experiments on the synthesis of element 115 in the reaction 243Am(48Ca,xn)291-x115". Physical Review C 69 (2): 021601.Bibcode 2004PhRvC..69b1601O. doi:10.1103/PhysRevC.69.021601.

[33] Lavrova, Natalie (2010). Word-Building Strategies in Modern English (http:/ / books. google. com/ books?id=Uy0uwU6n84wC&pg=PA95& dq=boron+ etymology#v=onepage& q=ununtrium& f=false). Germany: GRIN Verlag. p. 95. ISBN 9783640537198. . RetrievedAugust 9, 2011.

[34] Bugarski, Radovanović, Ranko, Milorad (2000). History and perspectives of language study (http:/ / books. google. com/books?id=B9clK7Jb6woC& pg=PA211& dq=aluminium+ etymology#v=onepage& q=aluminium etymology& f=false). Amsterdam, theNetherlands: John Benjamins Publishing Co.. p. 211. ISBN 9027236925. . Retrieved August 9, 2011.

[35] Weeks, Mary Elvira (1932). "The discovery of the elements. XIII. Some elements predicted by Mendeleeff". Journal of Chemical Education9 (9): 1605–1619. Bibcode 1932JChEd...9.1605W. doi:10.1021/ed009p1605.

[36] Venetskii, S. (1971). "Indium". Metallurgist 15 (2): 148–150. doi:10.1007/BF01088126.

Boron group 12

[37] "Online Etymology Dictionary" (http:/ / www. etymonline. com/ index. php?search=thallium& searchmode=none). etymonline. . Retrieved2011-07-27.

[38] Weeks, Mary Elvira (1932). "The discovery of the elements. XIII. Supplementary note on the discovery of thallium". Journal of ChemicalEducation 9 (12): 2078. Bibcode 1932JChEd...9.2078W. doi:10.1021/ed009p2078.

[39] C. Kotz, Treichel, R. Townsend, John, Paul, John (2009). Chemistry and chemical reactivity (http:/ / books. google. com/books?id=jcn6sgt7RpoC& pg=PA979& dq=boron+ group#v=onepage& q=boron group& f=false). 2. Belmont, Ca, USA: Thomson Books.p. 979. ISBN 0495387126. .

[40] Klein, Cornelis and Cornelius Hurlbut, Jr., Manual of Mineralogy, Wiley, 20th ed., 1985 pp. 343 - 347 ISBN 0-471-80580-7[41] Zbayolu, G.; Poslu, K. (1992). "Mining and Processing of Borates in Turkey". Mineral Processing and Extractive Metallurgy Review 9

(1–4): 245–254. doi:10.1080/08827509208952709.[42] Emsley, John (2001). "Aluminium" (http:/ / books. google. com/ ?id=j-Xu07p3cKwC& pg=PA24). Nature's Building Blocks: An A-Z Guide

to the Elements. Oxford, UK: Oxford University Press. pp. 22–26. ISBN 0198503407. .[43] Shan Xiao-quan, Wang Wen and Wen Bei (1992). "Determination of gallium in coal and coal fly ash by electrothermal atomic absorption

spectrometry using slurry sampling and nickel chemical modification". Journal of Analytical Atomic Spectrometry 7 (5): 761.doi:10.1039/JA9920700761.

[44] Schwarz-Schampera, M. Herzig, für Geowissenschaften und Rohstoffe, Ulrich, Peter, Bundesanstal (2002). Indium: geology, mineralogy,and economics (http:/ / books. google. com/ ?id=k7x_2_KnupMC& pg=PA161& dq=indium+ producers#v=onepage& q=indium producers&f=false). Berlin, Germany: Springer-Verlag. p. 161. ISBN 3-540-43135-7. .

[45] Roesky, Atwood, H.W, David A. (2003). Group 13 chemistry III: industrial applications (http:/ / books. google. com/books?id=HLVrEzba4UUC& printsec=frontcover& dq=group+ 13+ applications#v=onepage& q& f=false). Berlin, Germany:Springer-Verlag. pp. 3–10. ISBN 3-540-44105-0. .

[46] Gregory, J.W (2004). the elements of economic geology (http:/ / books. google. com/ books?id=I6IOAAAAQAAJ& pg=PA152&dq=aluminium+ uses#v=onepage& q=aluminium uses& f=false). p. 152. .

[47] Chatterjee, K.K. (2007). Uses Of Metals And Metallic Minerals (http:/ / books. google. com/ ?id=JfIaFtRqt3cC&printsec=frontcover#v=onepage& q& f=false). New Age International. p. 9. ISBN 9788122420401. .

[48] Chandler, Harry (1998). Metallurgy for the non-metallurgist (http:/ / books. google. com/ books?id=arupok8PTBEC& pg=PA59&dq=Gallium+ uses#v=onepage& q=Gallium uses& f=false). ASM International. p. 59. ISBN 0-87170-652-0. .

[49] Duncan, Richard (2008). Elements of Faith: Hydrogen to Tin, Faith Facts and Learning Lessons from the Periodic Table (http:/ / books.google. com/ ?id=kgVAlzGXx6oC& printsec=frontcover#v=onepage& q& f=false). Green Forest, AR: New Leaf Publishing Group. p. 66.ISBN 0-89051-547-1. .

[50] Us Dept of the Interior (2007). Minerals Yearbook: Metals And Minerals; 2005 (http:/ / books. google. com/ books?id=1jFYedAYAVAC&pg=SA36-PA1& dq=Indium+ uses#v=onepage& q=Indium uses& f=false). Washington, DC: US Government Printing Office. pp. 36–1.ISBN 978-1-4113-1980-6. .

[51] Schwarz-Schampera, M. Herzig, für Geowissenschaften und Rohstoffe, Ulrich, Peter, Bundesanstal (2002). Indium: geology, mineralogy,and economics (http:/ / books. google. com/ books?id=k7x_2_KnupMC& pg=PA167& dq=Indium+ uses#v=onepage& q=Indium uses&f=false). Berlin, Germany: Springer-Verlag. p. 169. ISBN 3-540-43135-7. .

[52] Mager, Jeanne (1998). Encyclopaedia of Occupational Health and Safety (http:/ / books. google. com/ books?id=nDhpLa1rl44C&pg=PT145& dq=thallium+ uses#v=onepage& q=thallium uses& f=false). Geneva, Switzerland: International Labor Organization Publications.p. section 63.40. ISBN 9789221098164. .

[53] Reilly, Conor (2004). The nutritional trace metals (http:/ / books. google. com/ books?id=VEcFymWfnYUC& pg=PA217& dq=boron+biological+ role#v=onepage& q=boron biological role& f=false). Ames, Iowa: Blackwell Publishing. p. 217. ISBN 1-4051-1040-6. .

[54] Crichton, Robert R. (2008). Biological inorganic chemistry: an introduction (http:/ / books. google. com/ books?id=j-Xu07p3cKwC&pg=PA192& dq=indium+ biological+ role#v=onepage& q=gallium biological role& f=false). UK. p. 9. ISBN 978-0-444-52740-0. .

[55] Fangsen, Xu (2007). Advances in plant and animal boron nutrition (http:/ / books. google. com/ books?id=Al8-rzgMqWoC& pg=PA82&dq=boron+ toxicity#v=onepage& q=boron toxicity& f=false). Dordrecht, Netherlands: Springer. p. 84. ISBN 1-4020-5382-7. .

[56] Lovatt, Carol J.; Bates, Loretta M. (1984). "Early effects of excess boron on photosynthesis and growth". Journal of Experimental Botany 35(3): 297–305. doi:10.1093/jxb/35.3.297.

[57] R. Dobbs, Michael (2009). Clinical neurotoxicology: syndromes, substances, environments (http:/ / books. google. com/books?id=Pmcy24y2HyMC& pg=PA277& dq=thallium+ toxicity#v=onepage& q=thallium toxicity& f=false). Philidelphia, Pa: Saunders.p. 277. ISBN 978-0-323-05260-3. .

Boron group 13

References

BibliographyDowns, Anthony John (1993). Chemistry of aluminium, gallium, indium, and thallium (http:/ / books. google. com/?id=v-04Kn758yIC& pg=PA201& dq=chemistry+ of+ aluminium,+ ga#v=onepage& q=chemistry of aluminium,ga& f=false). Chapman and Hall Inc.. pp. 197–201. ISBN 9780751401035.Emsley, John (2006). Nature's buildingblocks: an A-Z guide to the elements (http:/ / books. google. com/ ?id=j-Xu07p3cKwC& pg=PA192& dq=history+of+ indium#v=onepage& q=history of indium& f=false). Greenwood Press. p. 192. ISBN 9780198503408.

External links• oxide (chemical compound) – Britannica Online Encyclopedia (http:/ / www. britannica. com/ EBchecked/ topic/

436674/ oxide). Britannica.com. Retrieved on 2011-05-16.• Visual Elements: Group 13 (http:/ / www. rsc. org/ chemsoc/ visualelements/ pages/ data/ intro_groupiii_data.

html). Rsc.org. Retrieved on 2011-05-16.• Trends In Chemical Reactivity Of Group 13 Elements (http:/ / www. tutorvista. com/ content/ chemistry/

chemistry-iv/ p-block-elements/ reactivity-elements. php). Tutorvista.com. Retrieved on 2011-05-16.• (http:/ / www. innvista. com/ science/ chemistry/ elements/ etymolo. htm).innvista.com. Retrieved on 2011-07-27.• (http:/ / www. etymonline. com/ index. php?search=Aluminum& searchmode=none) etymonline.com Retrieved

on 2011-07-27

14

Elements

Boron

Boron

Appearance

black-brown

General properties

Name, symbol, number boron, B, 5

Pronunciation /ˈbɔrɒn/

Element category metalloid

Group, period, block 13, 2, p

Standard atomic weight 10.811(7) g·mol−1

Electron configuration [He] 2s2 2p1

Electrons per shell 2, 3 (Image)

Physical properties

Phase solid

Liquid density at m.p. 2.08 g·cm−3

Melting point 2349 K,2076 °C,3769 °F

Boiling point 4200 K,3927 °C,7101 °F

Heat of fusion 50.2 kJ·mol−1

Heat of vaporization 480 kJ·mol−1

Specific heat capacity (25 °C) 11.087 J·mol−1·K−1

Vapor pressure

P/Pa 1 10 100 1 k 10 k 100 k

at T/K 2348 2562 2822 3141 3545 4072

Atomic properties

Boron 15

Oxidation states 3, 2, 1[1]

(mildly acidic oxide)

Electronegativity 2.04 (Pauling scale)

Ionization energies(more)

1st: 800.6 kJ·mol−1

2nd: 2427.1 kJ·mol−1

3rd: 3659.7 kJ·mol−1

Atomic radius 90 pm

Covalent radius 84±3 pm

Van der Waals radius 192 pm

Miscellanea

Magnetic ordering diamagnetic[2]

Electrical resistivity (20 °C) ~106 Ω·m

Thermal conductivity (300 K) 27.4 W·m−1·K−1

Thermal expansion (25 °C) (ß form) 5–7 [3] µm·m−1·K−1

Speed of sound (thin rod) (20 °C) 16,200 m/s

Mohs hardness ~9.5

CAS registry number 7440-42-8

Most stable isotopes

iso NA half-life DM DE (MeV) DP

10B 19.9(7)%* 10B is stable with 5 neutron[4]

11B 80.1(7)%* 11B is stable with 6 neutron[4]

*Boron-10 content may be as low as 19.1% and ashigh as 20.3% in natural samples. Boron-11 is

the remainder in such cases.[5]

Boron (  /ˈbɔərɒn/) is the chemical element with atomic number 5 and the chemical symbol B. Boron is ametalloid. Because boron is produced entirely by cosmic ray spallation and not by stellar nucleosynthesis[6] , it is alow-abundance element in both the solar system and the Earth's crust. However, boron is concentrated on Earth bythe water-solubility of its more common naturally occurring compounds, the borate minerals. These are minedindustrially as evaporate ores, such as borax and kernite.Chemically uncombined boron is not found naturally on Earth. Industrially, very pure boron is produced withdifficulty, as boron tends to form refractory materials containing small amounts of carbon or other elements. Severalallotropes of boron exist: amorphous boron is a brown powder and crystalline boron is black, extremely hard (about9.5 on Mohs' scale), and a poor conductor at room temperature. Elemental boron is used as a dopant in thesemiconductor industry.The major industrial-scale uses of boron compounds are in sodium perborate bleaches, and the borax component of fiberglass insulation. Boron polymers and ceramics play specialized roles as high-strength lightweight structural and refractory materials. Boron compounds are used in silica-based glasses and ceramics to give them resistance to thermal shock. Boron-containing reagents are used for the synthesis of organic compounds, as intermediate in the

Boron 16

synthesis of fine chemicals. A few boron-containing organic pharmaceuticals are used, or are in study. Natural boronis composed of two stable isotopes, one of which (boron-10) has a number of uses as a neutron-capturing agent.In biology, borates have low toxicity in mammals (similar to table salt), but are more toxic to arthropods and areused as insecticides. Boric acid is mildly antimicrobial, and a natural boron-containing organic antibiotic is known.Boron is essential to life. Small amounts of boron compounds play a strengthening role in the cell walls of all plants,making boron necessary in soils. Experiments indicate a role for boron as an ultratrace element in animals, but thenature of its role in animal physiology is unknown.

History and etymologyThe name boron originates from the Arabic word بورق buraq or the Persian word بوره burah;[7] which are names forthe mineral borax.[8]

Sassolite

Boron compounds were known thousands of years ago. Borax was knownfrom the deserts of western Tibet, where it received the name of tincal,derived from the Sanskrit. Borax glazes were used in China from AD300, andsome tincal even reached the West, where the Persian alchemist Jābir ibnHayyān seems to mention it in 700. Marco Polo brought some glazes back toItaly in the 13th century. Agricola, around 1600, reports the use of borax as aflux in metallurgy. In 1777, boric acid was recognized in the hot springs(soffioni) near Florence, Italy, and became known as sal sedativum, withmainly medical uses. The rare mineral is called sassolite, which is found atSasso, Italy. Sasso was the main source of European borax from 1827 to1872, at which date American sources replaced it.[9] [10] Boron compounds

were relatively rarely used chemicals until the late 1800s when Francis Marion Smith's Pacific Coast BoraxCompany first popularized these compounds and made them in volume and hence cheap. [11]

Boron was not recognized as an element until it was isolated by Sir Humphry Davy[12] and by Joseph LouisGay-Lussac and Louis Jacques Thénard.[13] In 1808 Davy observed that electric current sent through a solution ofborates produced a brown precipitate on one of the electrodes. In his subsequent experiments he used potassium toreduce boric acid instead of electrolysis. He produced enough boron to confirm a new element and named theelement boracium.[12] Gay-Lussac and Thénard used iron to reduce boric acid at high temperatures. They showed byoxidizing boron with air that boric acid is an oxidation product of boron.[13] [14] Jöns Jakob Berzelius identifiedboron as an element in 1824.[15] Pure boron was arguably first produced by the American chemist Ezekiel Weintraubin 1909.[16] [17] [18]

Boron 17

Characteristics

Allotropes

Boron chunks

Boron is similar to carbon in its capability to form stable covalently bondedmolecular networks. Even nominally disordered (amorphous) boron containsregular boron icosahedra which are, however, bonded randomly to each otherwithout long-range order.[19] [20] Crystalline boron is a very hard, black materialwith a high melting point of above 2000 °C. It exists in four major polymorphs: α,β, γ and T. Whereas α, β and T phases are based on B12 icosahedra, the γ-phase canbe described as a rocksalt-type arrangement of the icosahedra and B2 atomicpairs.[21] It can be produced by compressing other boron phases to 12–20 GPa andheating to 1500–1800 °C; it remains stable after releasing the temperature andpressure. The T phase is produced at similar pressures, but higher temperatures of1800–2200 °C. As to the α and β phases, they might both coexist at ambientconditions with the β phase being more stable.[21] [22] [23] Compressing boronabove 160 GPa produces a boron phase with an as yet unknown structure, and thisphase is a superconductor at temperatures 6–12 K.[24]

Boron phase α β γ T

Symmetry Rhombohedral Rhombohedral Orthorhombic Tetragonal

Atoms/unit cell[21] 12 ~105 28

Density (g/cm3)[25]

[26]

[27]

[28] 2.46 2.35 2.52 2.36

Vickers hardness (GPa)[29]

[30] 42 45 50–58

Bulk modulus (GPa)[30]

[31] 185 224 227

Bandgap (eV)[30]

[32] 2 1.6 2.1

Chemistry of the elementElemental boron is rare and poorly studied because the material is extremely difficult to prepare. Most studies on"boron" involve samples that contain small amounts of carbon. Chemically, boron behaves more similarly to siliconthan to aluminium. Crystalline boron is chemically inert and resistant to attack by boiling hydrofluoric orhydrochloric acid. When finely divided, it is attacked slowly by hot concentrated hydrogen peroxide, hotconcentrated nitric acid, hot sulfuric acid or hot mixture of sulfuric and chromic acids.[17] [33]

The rate of oxidation of boron depends upon the crystallinity, particle size, purity and temperature. Boron does notreact with air at room temperature, but at higher temperatures it burns to form boron trioxide:

4 B + 3 O2 → 2 B2O3

Boron 18

Ball-and-stick model of tetraborate anion,[B4O5(OH)4]2−, as it occurs in crystalline borax,Na2[B4O5(OH)4]·8H2O. Boron atoms are pink,with bridging oxygens in red, and four hydroxyl

hydrogens in white. Note two borons aretrigonally bonded sp2 with no formal charge,while the other two borons are tetrahedrally

bonded sp3, each carrying a formal charge of −1.The oxidation state of all borons is III. Thismixture of boron coordination numbers and

formal charges is characteristic of natural boronminerals.

Boron undergoes halogenation to give trihalides, for example,2 B + 3 Br2 → 2 BBr3

These trihalides in practice are usually made from the oxides.

Chemical compounds

Boron (III) trifluoridestructure, showing "empty"boron p orbital in pi-typecoordinate covalent bonds

In its most familiar compounds, boron has the formal oxidation state III. These includeoxides, sulfides, nitrides, and halides.The trihalides adopt a planar trigonal structure. These compounds are Lewis acids in thatthey readily form adducts with electron-pair donors, which are called Lewis bases. Forexample, fluoride (F-) and boron trifluoride (BF3) combined to give the tetrafluoroborateanion, BF4

-. Boron trifluoride is used in the petrochemical industry as a catalyst. Thehalides react with water to form boric acid.

Boron is found in nature on Earth entirely as various oxides of B(III), often associatedwith other elements. The more than one hundred borates all feature boron in oxidationstate +3. These minerals resemble silicates in some respect, although boron is oftenfound not only in a tetrahedral coordination with oxygen, but also in a trigonal planarconfiguration. Unlike silicates, the boron minerals never feature boron with coordinationnumber greater than four. A typical motif is exemplified by the tetraborate anions of the common mineral borax,shown at left. The formal negative charge of the tetrahedral borate centers is balanced by metal cations in theminerals, such as the sodium (Na+) in borax.

The boron nitrides are notable for the variety of structures that they adopt. They adopt structures analogous to various allotropes of carbon, including graphite, diamond, and nanotubes. In the diamond-like structure called cubic boron nitride (tradename Borazon), boron atoms exist in the tetrahedral structure of carbons atoms in diamond, but one in every four B-N bonds can be viewed as a coordinate covalent bond, wherein two electrons are donated by the nitrogen atom which acts as the Lewis base to a bond to the Lewis acidic boron(III) centre. Cubic boron nitride,

Boron 19

among other applications, is used as an abrasive, as it has a hardness comparable with diamond (the two substancesare able to produce scratches on each other). In the BN compound analogue of graphite, hexagonal boron nitride(h-BN), the positively-charged boron and negatively-charged nitrogen atoms in each plane lie adjacent to theoppositely charged atom in the next plane. Consequently graphite and h-BN have very different properties, althoughboth are lubricants, as these planes slip past each other easily. However, h-BN is a relatively poor electrical andthermal conductor in the planar directions.

Organoboron chemistry

A large number of organoboron compounds are known and many are useful in organic synthesis. Organoboron(III)compounds are usually tetrahedral or trigonal planar, for example, tetraphenylborate (B(C6H5)4

-) vs triphenylborane(B(C6H5)3). Many are produced from hydroboration, which employs diborane (B2H6).

Compounds of B(I) and B(II)

Although these are not found on Earth naturally, boron forms a variety of stable compounds with formal oxidationstate less than three. As for many covalent compounds, formal oxidation states are often of little meaning in boronhydrides and metal borides. The halides also form derivatives of B(I) and B(II). BF, isoelectronic with N2, is notisolable in condensed form, but B2F4 and B4Cl4 are well characterized.[34]

Ball-and-stick model of superconductormagnesium diboride. Boron atoms lie in

hexagonal aromatic graphite-like layers, with acharge of −1 per boron. Magnesium (II) ions lie

between layers

Binary metal-boron compounds, the metal borides, feature boron inoxidation state less than III. Illustrative is magnesium diboride (MgB2).Each boron has a formal −1 charge and magnesium is assigned aformal charge of 2+. In this material, the boron centers are trigonalplanar, with an extra double bond for each boron, with the boron atomsforming sheets akin to the carbon in graphite. However, unlike the casewith hexagonal boron nitride which by comparison lacks electrons inthe plane of the covalent atoms, the delocalized electrons in the planeof magnesium diboride allow it to conduct electricity similar toisoelectronic graphite. In addition, in 2001 this material was found tobe a high-temperature superconductor.

Certain other metal borides find specialized applications as hardmaterials for cutting tools.From the structural perspective, the most distinctive chemical compounds of boron are the hydrides. Included in thisseries are the cluster compounds dodecaborate (B12H12

2-), decaborane (B10H14), and the carboranes such asC2B10H12. Characteristically such compounds feature boron with coordination numbers greater than four.

IsotopesBoron has two naturally occurring and stable isotopes, 11B (80.1%) and 10B (19.9%). The mass difference results ina wide range of δ11B values, which are defined as a fractional difference between the 11B and 10B and traditionallyexpressed in parts per thousand, in natural waters ranging from −16 to +59. There are 13 known isotopes of boron,the shortest-lived isotope is 7B which decays through proton emission and alpha decay. It has a half-life of 3.5×10−22

s. Isotopic fractionation of boron is controlled by the exchange reactions of the boron species B(OH)3 and[B(OH)4]−. Boron isotopes are also fractionated during mineral crystallization, during H2O phase changes inhydrothermal systems, and during hydrothermal alteration of rock. The latter effect results in preferential removal ofthe 10B(OH)4 ion onto clays. It results in solutions enriched in 11B(OH)3 and therefore may be responsible for thelarge 11B enrichment in seawater relative to both oceanic crust and continental crust; this difference may act as anisotopic signature.[35] The exotic 17B exhibits a nuclear halo, i.e. its radius is appreciably larger than that predictedby the liquid drop model.[36]

Boron 20

The 10B isotope is good at capturing thermal neutrons.[37] Natural boron is about 20% 10B and 80% 11B. The nuclearindustry enriches natural boron to nearly pure 10B. The less-valuable by-product, depleted boron, is nearly pure 11B.

Commercial isotope enrichment

Because of its high neutron cross-section, boron-10 is often used to control fission in nuclear reactors as aneutron-capturing substance.[38] Several industrial-scale enrichment processes have been developed, however onlythe fractionated vacuum distillation of the dimethyl ether adduct of boron trifluoride (DME-BF3) and columnchromatography of borates are being used.[39] [40]

Enriched boron (boron-10)

Neutron cross section of boron (top curve is for 10B and bottom curve for 11B)

Enriched boron or 10B is used in bothradiation shielding and in boron neutroncapture therapy. In the latter, acompound containing 10B is attached toa muscle near a tumor. The patient isthen treated with a relatively low doseof thermal neutrons. This causesenergetic and short range alpharadiation from the boron to bombard thetumor.[41] [42] [43] [44]

In nuclear reactors, 10B is used forreactivity control and in emergencyshutdown systems. It can serve eitherfunction in the form of borosilicatecontrol rods or as boric acid. Inpressurized water reactors, boric acid is added to the reactor coolant when the plant is shut down for refueling. It isthen slowly filtered out over many months as fissile material is used up and the fuel becomes less reactive.[45]

In future manned interplanetary spacecraft, 10B has a theoretical role as structural material (as boron fibers or BNnanotube material) which would also serve a special role in the radiation shield. One of the difficulties in dealingwith cosmic rays, which are mostly high energy protons, is that some secondary radiation from interaction of cosmicrays and spacecraft materials is high energy spallation neutrons. Such neutrons can be moderated by materials highin light elements such as polyethylene, but the moderated neutrons continue to be a radiation hazard unless activelyabsorbed in the shielding. Among light elements that absorb thermal neutrons, 6Li and 10B appear as potentialspacecraft structural materials which serve both for mechanical reinforcement and radiation protection.[46]

Depleted boron (boron-11)

Cosmic radiation will produce secondary neutrons if it hits spacecraft structures. Those neutrons will be captured in10B, if it is present in the spacecraft's semiconductors, producing a gamma ray, an alpha particle, and a lithium ion.These resultant decay products may then irradiate nearby semiconductor 'chip' structures, causing data loss (bitflipping, or single event upset). In radiation hardened semiconductor designs, one countermeasure is to use depletedboron which is greatly enriched in 11B and contains almost no 10B. 11B is largely immune to radiation damage.Depleted boron is a by-product of the nuclear industry.[45]

11B is also a candidate as a fuel for aneutronic fusion. When struck by a proton with energy of about 500 keV, it produces three alpha particles and 8.7 MeV of energy. Most other fusion reactions involving hydrogen and helium produce penetrating neutron radiation, which weakens reactor structures and induces long term radioactivity thereby endangering operating personnel. Whereas, the alpha particles from 11B fusion can be turned directly into electric

Boron 21

power, and all radiation stops as soon as the reactor is turned off.[47]

NMR spectroscopy

Both 10B and 11B possess nuclear spin. The nuclear spin of 10B is 3 and that of 11B is 3/2. These isotopes are,therefore, of use in nuclear magnetic resonance spectroscopy; and spectrometers specially adapted to detecting theboron-11 nuclei are available commercially. The 10B and 11B nuclei also cause splitting in the resonances of attachednuclei.[48]

Occurrence

A fragment of ulexite

Borax crystals

Boron is a relatively rare element in the Earth's crust, representing only0.001%. The worldwide commercial borate deposits are estimated at10 million tonnes.[49] [50] Turkey and the United States are the world'slargest producers of boron.[51] [52] Turkey has almost 72% of theworld’s boron reserves.[53] Boron does not appear on Earth inelemental form but is found combined in borax, boric acid, colemanite,kernite, ulexite and borates. Boric acid is sometimes found in volcanicspring waters.

Ulexite is one of over a hundred borate minerals; it is a fibrous crystalwhere individual fibers can guide light like optical fibers.[54]

Economically important sources of boron are rasorite (kernite) andtincal (borax ore). They are both found in the Mojave Desert ofCalifornia where the Rio Tinto Borax Mine (also known as the U.S.Borax Boron Mine) near Boron, CA is California's largest open-pitmine and the largest borax mine in the world, producing nearly half theworld's borates from this single site.[55] [56] . However, the largestborax deposits known, many still untapped, are in Central and WesternTurkey including the provinces of Eskişehir, Kütahya and Balıkesir.[57]

[58] [59]

ProductionThe production of boron compounds does not involve formation of elemental boron, but exploits the convenientavailability of borates.The earliest routes to elemental boron involved reduction of boric oxide with metals such as magnesium oraluminium. However the product is almost always contaminated with metal borides. Pure boron can be prepared byreducing volatile boron halides with hydrogen at high temperatures. Ultrapure boron, for the use in semiconductorindustry, is produced by the decomposition of diborane at high temperatures and then further purified with the zonemelting or Czochralski processes.[60]

Boron 22

Market trendEstimated global consumption of boron rose to a record 1.8 million tonnes of B2O3 in 2005, following a period ofstrong growth in demand from Asia, Europe and North America. Boron mining and refining capacities areconsidered to be adequate to meet expected levels of growth through the next decade.The form in which boron is consumed has changed in recent years. The use of ores like colemanite has declinedfollowing concerns over arsenic content. Consumers have moved towards the use of refined borates and boric acidthat have a lower pollutant content. The average cost of crystalline boron is $5/g.[61]

Increasing demand for boric acid has led a number of producers to invest in additional capacity. Eti Mine Companyof Turkey opened a new boric acid plant with the production capacity of 100,000 tonnes per year at Emet in 2003.Rio Tinto Group increased the capacity of its boron plant from 260,000 tonnes per year in 2003 to 310,000 tonnesper year by May 2005, with plans to grow this to 366,000 tonnes per year in 2006. Chinese boron producers havebeen unable to meet rapidly growing demand for high quality borates. This has led to imports of sodium tetraborate(borax) growing by a hundredfold between 2000 and 2005 and boric acid imports increasing by 28% per year overthe same period.[62] [63]

The rise in global demand has been driven by high growth rates in fiberglass and borosilicate production. A rapidincrease in the manufacture of reinforcement-grade fiberglass in Asia with a consequent increase in demand forborates has offset the development of boron-free reinforcement-grade fiberglass in Europe and the USA. The recentrises in energy prices may lead to greater use of insulation-grade fiberglass, with consequent growth in the boronconsumption. Roskill Consulting Group forecasts that world demand for boron will grow by 3.4% per year to reach21 million tonnes by 2010. The highest growth in demand is expected to be in Asia where demand could rise by anaverage 5.7% per year.[62] [64]

ApplicationsNearly all boron ore extracted from the Earth is destined for refinement into boric acid and sodium tetraboratepentahydrate. In the United States, 70% of the boron is used for the production of glass and ceramics.[65] [66]

Glass and ceramics

Borosilicate glassware. Displayed aretwo beakers and a test tube.

Borosilicate glass, which is typically 12–15% B2O3, 80% SiO2, and 2% Al2O3,has a low coefficient of thermal expansion giving it a good resistance to thermalshock. Duran and Pyrex are two major brand names for this glass, used both inlaboratory glassware and in consumer cookware and bakeware, chiefly for thisresistance.[67]

Boron filaments are high-strength, lightweight materials that are used chiefly foradvanced aerospace structures as a component of composite materials, as well aslimited production consumer and sporting goods such as golf clubs and fishingrods.[68] [69] The fibers can be produced by chemical vapor deposition of boronon a tungsten filament.[51] [70]

Boron fibers and sub-millimeter sized crystalline boron springs are produced bylaser-assisted chemical vapor deposition. Translation of the focused laser beamallows to produce even complex helical structures. Such structures show goodmechanical properties (elastic modulus 450 GPa, fracture strain 3.7%, fracturestress 17 GPa) and can be applied as reinforcement of ceramics or inmicromechanical systems.[71]

Boron 23

Detergent formulations and bleaching agentsBorax is used in various household laundry and cleaning products,[72] including the well-known "20 Mule TeamBorax" laundry booster and "Boraxo" powdered hand soap. It is also present in some tooth bleaching formulas.[66]

Sodium perborate serves as a source of active oxygen in many detergents, laundry detergents, cleaning products, andlaundry bleaches. However, despite its name, "Borateem" laundry bleach no longer contains any boron compounds,using sodium percarbonate instead as a bleaching agent.

InsecticidesBoric acid is used as an insecticide, notably against ants, fleas, and cockroaches.[73]

SemiconductorsBoron is a useful dopant for such semiconductors as silicon, germanium, and silicon carbide. Having one fewervalence electron than the host atom, it donates a hole resulting in p-type conductivity. Traditional method ofintroducing boron into semiconductors is via its atomic diffusion at high temperatures. This process uses either solid(B2O3), liquid (BBr3), or gaseous boron sources (B2H6 or BF3). However, after 1970s, it was mostly replaced by ionimplantation, which relies mostly on BF3 as a boron source.[74] Boron trichloride gas is also an important chemical insemiconductor industry, however not for doping but rather for plasma etching of metals and their oxides.[75]

Triethylborane is also injected into vapor deposition reactors as a boron source. Examples are the plasma depositionof boron-containing hard carbon films, silicon nitride-boron nitride films, and for doping of diamond film withboron.[76]

MagnetsBoron is a component of neodymium magnets (Nd2Fe14B), which are the strongest type of permanent magnet. Theyare found in a variety of domestic and professional electromechanical and electronic devices, such as magneticresonance imaging (MRI), various motors and actuators, computer HDDs, CD and DVD players, mobile phones,timer switches, speakers, and so on.[2]

High-hardness and abrasive compounds

Boron carbide is used for inner platesof ballistic vests

Several boron compounds are known for their extreme hardness and toughness.Boron carbide and cubic boron nitride powders are widely used as abrasives.Metal borides are used for coating tools through chemical vapor deposition orphysical vapor deposition. Implantation of boron ions into metals and alloys,through ion implantation or ion beam deposition, results in a spectacular increasein surface resistance and microhardness. Laser alloying has also beensuccessfully used for the same purpose. These borides are an alternative todiamond coated tools, and their (treated) surfaces have similar properties to thoseof the bulk boride.[77]

Boron 24

Boron carbide

Boron carbide is a ceramic material which is obtained by decomposing B2O3 with carbon in the electric furnace:2 B2O3 + 7 C → B4C + 6 CO

Boron carbide's stucture is only approximately B4C, and it shows a clear depletion of carbon from this suggestedstoichiometric ratio. This is due to its very complex structure. The substance can be seen with empirical formulaB12C3 (i.e., with B12 dodecahedra being a motif), but with less carbon as the suggested C3 units are replaced withB-C chains, and there are smaller (B6) octahedra present as well. (See the article for structural analysis).The repeating polymer plus semi-crystalline structure of boron carbide gives it great structural strength per weight. Itis used in tank armor, bulletproof vests, and numerous other structural applications.Boron carbide's ability to absorb neutrons without forming long-lived radionuclides (especially when doped withextra boron-10) makes the material attractive as an absorbent for neutron radiation arising in nuclear power plants.Nuclear applications of boron carbide include shielding, control rods and shut-down pellets. Within control rods,boron carbide is often powdered, to increase its surface area.[78]

Mechanical properties of BCN solids [79] and ReB2[80]

Material Diamond cubic-BC2N cubic-BC

5cubic-BN B

4C ReB

2

Vickers hardness (GPa) 115 76 71 62 38 22

Fracture toughness (MPa m1/2) 5.3 4.5 9.5 6.8 3.5

Other superhard boron compounds

• Heterodiamond (also called BCN);• Boron nitride. This material is isoelectronic to carbon. Similar to carbon, it has both hexagonal (soft graphite-like

h-BN) and cubic (hard, diamond-like c-BN) forms. h-BN is used as a high temperature component and lubricant.c-BN, also known under commercial name borazon,[81] is a superior abrasive. Its hardness is only slightly smaller,but chemical stability is superior to that of diamond.

• Rhenium diboride can be produced at ambient pressures, but is rather expensive because of rhenium. Thehardness of ReB2 exhibits considerable anisotropy because of its hexagonal layered structure. Its value iscomparable to that of tungsten carbide, silicon carbide, titanium diboride or zirconium diboride.[80]

• AlMgB14 + TiB2 composites possess high hardness and wear resistance and are used in either bulk form or ascoatings for components exposed to high temperatures and wear loads.[82]

Boron 25

Shielding in nuclear reactorsBoron shielding is used as a control for nuclear reactors, taking advantage of its high cross-section for neutroncapture.

Other nonmedical uses

Boron-containing emergency flare

• Because of its distinctive green flame, amorphous boron is used inpyrotechnic flares.[83] *Starch and casein-based adhesives containsodium tetraborate decahydrate (Na2B4O7•10 H2O)

• Some anti-corrosion systems contain borax.[84]

• Sodium borates are used as a flux for soldering silver and gold andwith ammonium chloride for welding ferrous metals.[85] They arealso fire retarding additives to plastics and rubber articles.[86]

• Boric acid (also known as orthoboric acid) H3BO3 is used in theproduction of textile fiberglass and flat panel displays [66] [87] and inmany PVAc and PVOH based adhesives.

• Triethylborane is a substance which ignites the JP-7 fuel of the Pratt & Whitney J58 turbojet/ramjet enginespowering the Lockheed SR-71 Blackbird.[88] It was also used to ignite the F-1 Engines on the Saturn V Rocketutilized by NASA's Apollo and Skylab programs from 1967 until 1973. Triethylborane is suitable for this becauseof its pyrophoric properties, especially the fact that it burns with a very high temperature.[89] Triethylborane is anindustrial initiator in radical reactions, where it is effective even at low temperatures.

Research areasMagnesium diboride is an important superconducting material with the transition temperature of 39 K. MgB2 wiresare produced with the powder-in-tube process and applied in superconducting magnets.[90] [91]

Amorphous boron is used as a melting point depressant in nickel-chromium braze alloys.[92]

Hexagonal boron nitride forms atomically thin layers, which have been used to enhance the electron mobility ingraphene devices.[93] [94] It also forms nanotubular structures (BNNTs), which have with high strength, highchemical stability, and high thermal conductivity, among its list of desirable properties.[95]

Biological roleThere is a boron-containing natural antibiotic, boromycin, isolated from streptomyces.[96] [97] Boron is an essentialplant nutrient, required primarily for maintaining the integrity of cell walls. Conversely, high soil concentrations of >1.0 ppm can cause marginal and tip necrosis in leaves as well as poor overall growth performance. Levels as low as0.8 ppm can cause these same symptoms to appear in plants particularly sensitive to boron in the soil. Nearly allplants, even those somewhat tolerant of boron in the soil, will show at least some symptoms of boron toxicity whenboron content in the soil is greater than 1.8 ppm. When this content exceeds 2.0 ppm, few plants will perform welland some may not survive. When boron levels in plant tissue exceed 200 ppm symptoms of boron toxicity are likelyto appear.[98] [99] [100]

As an ultratrace element, boron is necessary for the optimal health of rats, although it is necessary in such smallamounts that ultrapurified foods and dust filtration of air is necessary to induce boron deficiency, which manifest aspoor coat or hair quality. Presumably, boron is necessary to other mammals. No deficiency syndrome in humans hasbeen described. Small amounts of boron occur widely in the diet, and the amounts needed in the diet would, byanalogy with rodent studies, be very small. The exact physiological role of boron in the animal kingdom is poorlyunderstood.[101]

Boron 26

Boron occurs in all foods produced from plants. Since 1989 its nutritional value has been argued. It is thought thatboron plays several biochemical roles in animals, including humans.[102] The U.S. Department of agricultureconducted an experiment in which postmenopausal women took 3 mg of boron a day. The results showed thatsupplemental boron reduced excretion of calcium by 44%, and activated estrogen and vitamin D, suggesting apossible role in the suppression of osteoporosis. However, whether these effects were conventionally nutritional, ormedicinal, could not be determined. The U.S. National Institutes of Health states that "Total daily boron intake innormal human diets ranges from 2.1–4.3 mg boron/day."[103] [104]

Analytical quantificationFor determination of boron content in food or materials the colorimetric curcumin method is used. Boron has to betransferred to boric acid or borates and on reaction with curcumin in acidic solution, a red colored boron-chelatecomplex, rosocyanine, is formed.[105]

Boron pharmaceuticals and biologicalsBoric acid has antiseptic, antifungal, and antiviral properties and for this reasons is applied as a water clarifier inswimming pool water treatment.[106] Mild solutions of boric acid have been used as eye antiseptics.A number of potential boronated pharmaceuticals using boron-10, have been prepared for use in boron neutroncapture therapy (BNCT).[107]

Some boron compounds show promise in treating arthritis, though none have as yet been generally approved for thepurpose.[108]

Boron is used as an intermediate in pharmaceutical synthesis, but it appeared as an active element in itsfirst-approved organic pharamaceutical in bortezomib, a new class of drug called proteasome inhibitors, which areactive in myeloma and one form of lymphoma. The boron atom in bortezomib binds the catalytic site of the 26Sproteasome[109] with high affinity and specificity.

Health issuesElemental boron, boron oxide, boric acid, borates, and many organoboron compounds are non-toxic to humans andanimals (approximately similar to table salt). The LD50 (dose at which there is 50% mortality) for animals is about6 g per kg of body weight. Substances with LD50 above 2 g are considered non-toxic. The minimum lethal dose forhumans has not been established, but an intake of 4 g/day was reported without incidents, and medical dosages of20 g of boric acid for neutron capture therapy caused no problems. Fish have survived for 30 min in a saturated boricacid solution and can survive longer in strong borax solutions.[110] Boric acid is more toxic to insects than tomammals, and is routinely used as an insecticide.[73]

The boranes and similar gaseous compounds are quite poisonous. As usual, it is not an element that is intrinsicallypoisonous, but toxicity depends on structure.[9] [10]

The boranes (boron hydrogen compounds) are toxic as well as highly flammable and require special care whenhandling. Sodium borohydride presents a fire hazard due to its reducing nature, and the liberation of hydrogen oncontact with acid. Boron halides are corrosive.[111]

Congenital endothelial dystrophy type 2, a rare form of corneal dystrophy, is linked to mutations in SLC4A11 genethat encodes a transporter reportedly regulating the intracellular concentration of boron.[112]

Boron 27

References[1] Zhang, K.Q.; Guo, B.; Braun, V.; Dulick, M.; Bernath, P.F. (1995). "Infrared Emission Spectroscopy of BF and AIF" (http:/ / bernath.

uwaterloo. ca/ media/ 125. pdf). J. Molecular Spectroscopy 170: 82. doi:10.1006/jmsp.1995.1058. .[2] Lide, David R. (ed.) (2000). Magnetic susceptibility of the elements and inorganic compounds, in Handbook of Chemistry and Physics (http:/

/ www-d0. fnal. gov/ hardware/ cal/ lvps_info/ engineering/ elementmagn. pdf). CRC press. ISBN 0849304814. .[3] Holcombe Jr., C. E.; Smith, D. D.; Lorc, J. D.; Duerlesen, W. K.; Carpenter; D. A. (October 1973). "Physical-Chemical Properties of

beta-Rhombohedral Boron". High Temp. Sci. 5 (5): 349–57.[4] "Atomic Weights and Isotopic Compositions for All Elements" (http:/ / physics. nist. gov/ cgi-bin/ Compositions/ stand_alone. pl). National

Institute of Standards and Technology. . Retrieved 2008-09-21.[5] Szegedi, S.; Váradi, M.; Buczkó, Cs. M.; Várnagy, M.; Sztaricskai, T. (1990). "Determination of boron in glass by neutron transmission

method". Journal of Radioanalytical and Nuclear Chemistry Letters 146 (3): 177. doi:10.1007/BF02165219.[6] "Q & A: Where does the element Boron come from?" (http:/ / van. physics. illinois. edu/ qa/ listing. php?id=17594). . Retrieved 2011-12-04.[7] Shipley, Joseph T. (2001). The Origins of English Words: A Discursive Dictionary of Indo-European Roots (http:/ / books. google. com/

?id=m1UKpE4YEkEC& pg=PA83). JHU Press. ISBN 9780801867842. .[8] "Etymology of Elements" (http:/ / www. innvista. com/ science/ chemistry/ elements/ etymolo. htm). innvista. . Retrieved 2009-06-06.[9] Garrett, Donald E. (1998). Borates: handbook of deposits, processing, properties, and use. Academic Press. pp. 102;385–386.

ISBN 0122760603.[10] "Boron" (http:/ / mysite. du. edu/ ~jcalvert/ phys/ boron. htm). . Retrieved 2009-05-05.[11] Hildebrand, G. H. (1982) "Borax Pioneer: Francis Marion Smith." San Diego: Howell-North Books. p. 267 ISBN 0-8310-7148-6[12] Davy H (1809). "An account of some new analytical researches on the nature of certain bodies, particularly the alkalies, phosphorus,

sulphur, carbonaceous matter, and the acids hitherto undecomposed: with some general observations on chemical theory" (http:/ / books.google. com/ books?id=gpwEAAAAYAAJ& pg=PA140#v=onepage& q& f=false). Philosophical Transactions of the Royal Society ofLondon 99: 33–104. .

[13] Gay Lussac, J.L. and Thenard, L.J. (1808) "Sur la décomposition et la recomposition de l'acide boracique," (http:/ / books. google. com/books?id=e6Aw616K5ysC& pg=PA169#v=onepage& q& f=false) Annales de chimie [later: Annales de chemie et de physique], vol. 68, pp.169–174.

[14] Weeks, Mary Elvira (1933). "XII. Other Elements Isolated with the Aid of Potassium and Sodium: Beryllium, Boron, Silicon andAluminum" (http:/ / books. google. com/ books?id=SJIk9BPdNWcC& pg=PA156). The Discovery of the Elements. Easton, PA: Journal ofChemical Education. p. 156. ISBN 0-7661-3872-0. .

[15] Berzelius produced boron by reducing a borofluoride salt; specifically, by heating potassium borofluoride with potassium metal. See:Berzelius, J. (1824) "Undersökning af flusspatssyran och dess märkvärdigaste föreningar" (http:/ / books. google. com/books?id=pJlPAAAAYAAJ& pg=PA46#v=onepage& q& f=false) (Part 2) (Investigation of hydrofluoric acid and of its most noteworthycompounds), Kongliga Vetenskaps-Academiens Handlingar (Proceedings of the Royal Science Academy), vol. 12, pp. 46-98; see especiallypp. 88ff. Reprinted in German as: Berzelius, J. J. (1824) "Untersuchungen über die Flußspathsäure und deren merkwürdigste Verbindungen"(http:/ / gallica. bnf. fr/ ark:/ 12148/ bpt6k150878/ f123. image. r=Annalen der Physic. langEN), Poggendorff's Annalen der Physik undChemie, vol. 78, pages 113-150.

[16] Weintraub, Ezekiel (1909). "Preparation and properties of pure boron". Transactions of the American Electrochemical Society 16: 165–184.[17] Laubengayer, A. W.; Hurd, D. T.; Newkirk, A. E.; Hoard, J. L. (1943). "Boron. I. Preparation and Properties of Pure Crystalline Boron".

Journal of the American Chemical Society 65 (10): 1924–1931. doi:10.1021/ja01250a036.[18] Borchert, W. ; Dietz, W. ; Koelker, H. (1970). "Crystal Growth of Beta–Rhombohedrical Boron". Zeitschrift für Angewandte Physik 29:

277. OSTI 4098583.[19] Delaplane, R.G.; Dahlborg, U; Graneli, B; Fischer, P; Lundstrom, T (1988). "A neutron diffraction study of amorphous boron". Journal of

Non-Crystalline Solids 104 (2–3): 249. Bibcode 1988JNCS..104..249D. doi:10.1016/0022-3093(88)90395-X.[20] R.G. Delaplane; Dahlborg, U; Howells, W; Lundstrom, T (1988). "A neutron diffraction study of amorphous boron using a pulsed source".

Journal of Non-Crystalline Solids 106: 66. Bibcode 1988JNCS..106...66D. doi:10.1016/0022-3093(88)90229-3.[21] Oganov A.R., Chen J., Gatti C., Ma Y.-M., Yu T., Liu Z., Glass C.W., Ma Y.-Z., Kurakevych O.O., Solozhenko V.L. (2009). "Ionic

high-pressure form of elemental boron" (http:/ / mysbfiles. stonybrook. edu/ ~aoganov/ files/ Boron-Nature-2009. pdf). Nature 457 (7231):863–867. Bibcode 2009Natur.457..863O. doi:10.1038/nature07736. PMID 19182772. .

[22] van Setten M.J., Uijttewaal M.A., de Wijs G.A., de Groot R.A. (2007). "Thermodynamic stability of boron: The role of defects and zeropoint motion". J. Am. Chem. Soc. 129 (9): 2458–2465. doi:10.1021/ja0631246. PMID 17295480.

[23] Widom M., Mihalkovic M. (2008). "Symmetry-broken crystal structure of elemental boron at low temperature". Phys. Rev. B 77 (6):064113. Bibcode 2008PhRvB..77f4113W. doi:10.1103/PhysRevB.77.064113.

[24] Eremets, M. I.; Struzhkin, VV; Mao, H; Hemley, RJ (2001). "Superconductivity in Boron". Science 293 (5528): 272.Bibcode 2001Sci...293..272E. doi:10.1126/science.1062286. PMID 11452118.

[25] Wentorf Jr, R. H. (1965). "Boron: Another Form" (http:/ / www. sciencemag. org/ cgi/ content/ abstract/ 147/ 3653/ 49). Science 147 (3653):49–50 (Powder Diffraction File database (CAS number 7440–42–8)). Bibcode 1965Sci...147...49W. doi:10.1126/science.147.3653.49.PMID 17799779. .

Boron 28

[26] Hoard, J. L.; Sullenger, D. B.; Kennard, C. H. L.; Hughes, R. E. (1970). "The structure analysis of β-rhombohedral boron". J. Solid StateChem. 1 (2): 268–277. Bibcode 1970JSSCh...1..268H. doi:10.1016/0022-4596(70)90022-8.

[27] Will, G.; Kiefer, B. (2001). "Electron Deformation Density in Rhombohedral a-Boron". Zeitschrift für anorganische und allgemeine Chemie627 (9): 2100. doi:10.1002/1521-3749(200109)627:9<2100::AID-ZAAC2100>3.0.CO;2-G.

[28] Talley, C. P.; LaPlaca, S.; Post, B. (1960). "A new polymorph of boron". Acta Crystallogr. 13 (3): 271. doi:10.1107/S0365110X60000613.[29] Solozhenko, V. L.; Kurakevych, O. O.; Oganov, A. R. (2008). "On the hardness of a new boron phase, orthorhombic γ-B28". Journal of

Superhard Materials 30 (6): 428–429. doi:10.3103/S1063457608060117.[30] Zarechnaya, E. Yu.; Dubrovinsky, L.; Dubrovinskaia, N.; Filinchuk, Y.; Chernyshov, D.; Dmitriev, V.; Miyajima, N.; El Goresy, A. et al.

(2009). "Superhard Semiconducting Optically Transparent High Pressure Phase of Boron". Phys. Rev. Lett. 102 (18): 185501.Bibcode 2009PhRvL.102r5501Z. doi:10.1103/PhysRevLett.102.185501. PMID 19518885.

[31] Nelmes, R. J.; Loveday, J. S.; Allan, D. R.; Hull, S.; Hamel, G.; Grima, P.; Hull, S. (1993). "Neutron- and x-ray-diffraction measurements ofthe bulk modulus of boron". Phys. Rev. B 47 (13): 7668. Bibcode 1993PhRvB..47.7668N. doi:10.1103/PhysRevB.47.7668.

[32] ed. Madelung, O. (1983). Landolt-Bornstein, New Series. 17e. Springer-Verlag, Berlin.[33] "WebElements.com – Boron" (http:/ / www. webelements. com/ boron/ ). . Retrieved 2009-05-05.[34] Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Oxford: Butterworth-Heinemann. ISBN 0080379419.[35] Barth, S. (1997). "Boron isotopic analysis of natural fresh and saline waters by negative thermal ionization mass spectrometry". Chemical

Geology 143 (3–4): 255–261. doi:10.1016/S0009-2541(97)00107-1.[36] Liu, Z. (2003). "Two-body and three-body halo nuclei". Science in China G: Physics Mechanics and Astronomy 46 (4): 441.

Bibcode 2003ScChG..46..441L. doi:10.1360/03yw0027.[37] See neutron cross section#typical cross sections[38] "Results of the B4C Control Rod Test QUENCH-07" (http:/ / bibliothek. fzk. de/ zb/ berichte/ FZKA6746. pdf). .[39] "Commissioning of Boron Enrichment Plant" (http:/ / library. igcar. gov. in/ html/ Contents/ IGCNewsletter/ nl48/ A2. htm). Indira Gandhi

Centre for Atomic Research. . Retrieved 2008-09-21.[40] see Aida, Masao; Fujii, Yasuhiko; Okamoto, Makoto (1986). "Chromatographic Enrichment of 10B by Using Weak-Base Anion-Exchange

Resin". Separation Science and Technology 21 (6): 643–654. doi:10.1080/01496398608056140. showing an enrichment from 18% to above94%.

[41] Barth, Rolf F. (2003). "A Critical Assessment of Boron Neutron Capture Therapy: An Overview". Journal of Neuro-Oncology 62 (1): 1–5.doi:10.1023/A:1023262817500.

[42] Coderre, Jeffrey A.; Morris, GM (1999). "The Radiation Biology of Boron Neutron Capture Therapy". Radiation Research 151 (1): 1–18.doi:10.2307/3579742. JSTOR 3579742. PMID 9973079.

[43] Barth, Rolf F.; S; F (15 February 1990). "Boron Neutron Capture Therapy of Cancer" (http:/ / cancerres. aacrjournals. org/ cgi/ content/citation/ 50/ 4/ 1061). Cancer Research 50 (4): 1061–1070. PMID 2404588. .

[44] "Boron Neutron Capture Therapy - An Overview" (http:/ / www. pharmainfo. net/ reviews/ boron-neutron-capture-therapy-overview).Pharmainfo.net. 2006-08-22. . Retrieved 2011-11-07.

[45] Duderstadt, James J.; Hamilton, Louis J. (1976). Nuclear Reactor Analysis. Wiley-Interscience. p. 245. ISBN 0471223638.[46] J. Yu; Chen, Y.; Elliman, R. G.; Petravic, M. (2006). "Isotopically Enriched 10BN Nanotubes" (http:/ / www. rsphysse. anu. edu. au/

nanotube/ pdf/ B10Nnanotubes. pdf). Advanced Materials 18 (16): 2157. doi:10.1002/adma.200600231. .[47] Nevins, W. M. (1998). "A Review of Confinement Requirements for Advanced Fuels". Journal of Fusion Energy 17 (1): 25–32.

doi:10.1023/A:1022513215080.[48] "Boron NMR" (http:/ / rmn. iqfr. csic. es/ guide/ eNMR/ chem/ B. html). BRUKER Biospin. . Retrieved 2009-05-05.[49] Argust, Peter (1998). "Distribution of boron in the environment". Biological Trace Element Research 66 (1–3): 131–143.

doi:10.1007/BF02783133. PMID 10050915.[50] Woods, William G. (1994). "An Introduction to Boron: History, Sources, Uses, and Chemistry". Environmental Health Perspectives 102,

Supplement 7: 5–11. PMC 1566642. PMID 7889881.[51] Kostick, Dennis S. (2006). "Mineral Yearbook: Boron" (http:/ / minerals. usgs. gov/ minerals/ pubs/ commodity/ boron/ myb1-2006-boron.

pdf) (PDF). United States Geological Survey. . Retrieved 2008-09-20.[52] "Mineral Commodity Summaries: Boron" (http:/ / minerals. usgs. gov/ minerals/ pubs/ commodity/ boron/ mcs-2008-boron. pdf) (PDF).

United States Geological Survey. 2008. . Retrieved 2008-09-20.[53] "Developments in the Economic Sector (of Turkey)" (http:/ / www. byegm. gov. tr/ YAYINLARIMIZ/ kitaplar/ turkiye2006/ english/

302-303. htm). Turkish government. . Retrieved 2007-12-21.[54] Simmons, R.; Ahsian, N.; Raven, H. (2007). The Book of Stones: Who They Are and What They Teach. North Atlantic Books. pp. 421–422.

ISBN 1556436688.[55] The Center for Land Use Interpretation (http:/ / ludb. clui. org/ ex/ i/ CA4982/ )[56] Rio Tinto (http:/ / www. riotinto. com/ ourproducts/ 218_our_companies_4438. asp)[57] Kistler, R. B. (1994). "Boron and Borates" (http:/ / kisi. deu. edu. tr/ cahit. helvaci/ Boron. pdf). Industrial Minerals and Rocks (Society of

Mining, Metallurgy and Exploration, Inc.): 171–186. .[58] Zbayolu, G.; Poslu, K. (1992). "Mining and Processing of Borates in Turkey". Mineral Processing and Extractive Metallurgy Review 9

(1–4): 245–254. doi:10.1080/08827509208952709.

Boron 29

[59] Kar, Y.; Şen, Nejdet; Demİrbaş, Ayhan (2006). "Boron Minerals in Turkey, Their Application Areas and Importance for the Country'sEconomy". Minerals & Energy – Raw Materials Report 20 (3–4): 2–10. doi:10.1080/14041040500504293.

[60] Berger, L. I. (1996). Semiconductor materials. CRC Press. pp. 37–43. ISBN 0849389127.[61] "Boron Properties" (http:/ / www. rareearth. org/ boron_properties. htm). Los Alamos National Laboratory. . Retrieved 2008-09-18.[62] The Economics of Boron, 11th edition. Roskill Information Services, Ltd.. 2006. ISBN 0862145163.[63] "Raw and Manufactured Materials 2006 Overview" (http:/ / www. ceramicindustry. com/ Articles/ Cover_Story/

4b0b7a6ed1cb8010VgnVCM100000f932a8c0____). . Retrieved 2009-05-05.[64] "Roskill reports: boron" (http:/ / www. roskill. com/ reports/ boron). Roskill. . Retrieved 2009-05-05.[65] "Boron: Statistics and Information" (http:/ / minerals. usgs. gov/ minerals/ pubs/ commodity/ boron/ ). USGS. . Retrieved 2009-05-05.[66] Hammond, C. R. (2004). The Elements, in Handbook of Chemistry and Physics 81st edition. CRC press. ISBN 0849304857.[67] Pfaender, H. G. (1996). Schott guide to glass (2 ed.). Springer. p. 122. ISBN 041262060X.[68] Herring, H. W. (1966). "Selected Mechanical and Physical Properties of Boron Filaments" (http:/ / ntrs. nasa. gov/ archive/ nasa/ casi. ntrs.

nasa. gov/ 19660005941_1966005941. pdf). NASA. . Retrieved 2008-09-20.[69] Layden, G. K. (1973). "Fracture behaviour of boron filaments". Journal of Materials Science 8 (11): 1581–1589.

Bibcode 1973JMatS...8.1581L. doi:10.1007/BF00754893.[70] Cooke, Theodore F. (1991). "Inorganic Fibers—A Literature Review". Journal of the American Ceramic Society 74 (12): 2959–2978.

doi:10.1111/j.1151-2916.1991.tb04289.x.[71] Johansson, S.; Schweitz, Jan-Åke; Westberg, Helena; Boman, Mats (1992). "Microfabrication of three-dimensional boron structures by laser

chemical processing". Journal Applied Physics 72 (12): 5956–5963. Bibcode 1992JAP....72.5956J. doi:10.1063/1.351904.[72] Record (http:/ / householdproducts. nlm. nih. gov/ cgi-bin/ household/ brands?tbl=chem& id=136) in the Household Products Database of

NLM[73] Klotz, J. H.; Moss, JI; Zhao, R; Davis Jr, LR; Patterson, RS (1994). "Oral toxicity of boric acid and other boron compounds to immature cat

fleas (Siphonaptera: Pulicidae)" (http:/ / grande. nal. usda. gov/ ibids/ index. php?mode2=detail& origin=ibids_references& therow=51171). J.Econ. Entomol. 87 (6): 1534–1536. PMID 7836612. .

[74] May, Gary S.; Spanos, Costas J. (2006). Fundamentals of semiconductor manufacturing and process control. John Wiley and Sons.pp. 51–54. ISBN 0471784060.

[75] Sherer, J. Michael (2005). Semiconductor industry: wafer fab exhaust management. CRC Press. pp. 39–60. ISBN 1574447203.[76] Ehrenfried Zschech, Caroline Whelan, Thomas Mikolajick (2005). Materials for information technology: devices, interconnects and

packaging. Birkhäuser. p. 44. ISBN 1852339411.[77] Gogotsi, Y. G. and Andrievski, R.A. (1999). Materials Science of Carbides, Nitrides and Borides. Springer. pp. 270–270.

ISBN 0792357078.[78] Weimer, Alan W. (1997). Carbide, Nitride and Boride Materials Synthesis and Processing. Chapman & Hall (London, New York).

ISBN 0-412-54060-6.[79] Solozhenko, V. L.; Kurakevych, Oleksandr O.; Le Godec, Yann; Mezouar, Mohamed; Mezouar, Mohamed (2009). "Ultimate Metastable

Solubility of Boron in Diamond: Synthesis of Superhard Diamondlike BC5". Phys. Rev. Lett. 102 (1): 015506.Bibcode 2009PhRvL.102a5506S. doi:10.1103/PhysRevLett.102.015506. PMID 19257210.

[80] Qin, Jiaqian; He, Duanwei; Wang, Jianghua; Fang, Leiming; Lei, Li; Li, Yongjun; Hu, Juan; Kou, Zili et al. (2008). "Is Rhenium Diboride aSuperhard Material?". Advanced Materials 20 (24): 4780. doi:10.1002/adma.200801471.

[81] Wentorf, R. H. (1957). "Cubic form of boron nitride". J. Chem Phys. 26 (4): 956. Bibcode 1957JChPh..26..956W. doi:10.1063/1.1745964.[82] Schmidt, Jürgen; Boehling, Marian; Burkhardt, Ulrich; Grin, Yuri (2007). "Preparation of titanium diboride TiB2 by spark plasma sintering

at slow heating rate". Science and Technology of Advanced Materials 8 (5): 376. Bibcode 2007STAdM...8..376S.doi:10.1016/j.stam.2007.06.009.

[83] Kosanke, B. J. et al. (2004). Pyrotechnic Chemistry. Journal of Pyrotechnics,. p. 419. ISBN 9781889526157.[84] "Borax Decahydrate" (http:/ / chemicalland21. com/ industrialchem/ inorganic/ BORAX DECAHYDRATE. htm). . Retrieved 2009-05-05.[85] Davies, A. C. (1992). The Science and Practice of Welding: Welding science and technology. Cambridge University Press. p. 56.

ISBN 052143565X.[86] Horrocks, A.R. and Price, D. (2001). Fire Retardant Materials. Woodhead Publishing Ltd.. p. 55. ISBN 1855734192.[87] Ide, F. (2003). "Information technology and polymers. Flat panel display" (http:/ / sciencelinks. jp/ j-east/ article/ 200311/

000020031103A0287941. php). Engineering Materials 51: 84. .[88] "Lockheed SR-71 Blackbird" (http:/ / www. marchfield. org/ sr71a. htm). March Field Air Museum. . Retrieved 2009-05-05.[89] A. Young (2008). The Saturn V F-1 Engine: Powering Apollo Into History. Springer. p. 86. ISBN 0387096299.[90] Canfield,, Paul C.; Crabtree, George W. (2003). "Magnesium Diboride: Better Late than Never" (http:/ / www. cmp. ameslab. gov/

personnel/ canfield/ pub/ pt0303. pdf). Physics Today 56 (3): 34–41. Bibcode 2003PhT....56c..34C. doi:10.1063/1.1570770. .[91] Braccini, Valeria; Nardelli, D; Penco, R; Grasso, G (2007). "Development of ex situ processed MgB2 wires and their applications to

magnets". Physica C: Superconductivity 456 (1–2): 209–217. Bibcode 2007PhyC..456..209B. doi:10.1016/j.physc.2007.01.030.[92] Wu, Xiaowei; Chandel, R. S.; Li, Hang (2001). "Evaluation of transient liquid phase bonding between nickel-based superalloys". Journal of

Materials Science 36 (6): 1539–1546. doi:10.1023/A:1017513200502.[93] Dean,, C. R.; Young,, A. F.; Meric,, I.; Lee,, C.; Wang,, L.; Sorgenfrei,, S.; Watanabe,, K.; Taniguchi,, T. et al. (2010). "Boron nitride

substrates for high-quality graphene electronics". Nature Nanotechnology 5: 722–726. doi:10.1038/nnano.2010.172.

Boron 30

[94] Gannett, W.; Regan, W.; Watanabe, K.; Taniguchi, T.; Crommie, M. F.; Zettl, A. (2010). "Boron nitride substrates for high mobilitychemical vapor deposited graphene". Applied Physics Letters 98: 242105. doi:10.1063/1.3599708.

[95] Zettl, Alex; Cohen, Marvin (2010). "The physics of boron nitride nanotubes". Physics Today 63: 34–38. doi:10.1063/1.3518210.[96] Hütter, R. et al.; Keller-Schierlein, W; Knüsel, F; Prelog, V; Rodgers Jr, GC; Suter, P; Vogel, G; Voser, W et al. (1967).

"Stoffwechselprodukte von Mikroorganismen. 57. Mitteilung. Boromycin". Helvetica Chimica Acta 50 (6): 1533–1539.doi:10.1002/hlca.19670500612. PMID 6081908.

[97] Dunitz, J. D. et al.; Hawley, DM; Miklos, D; White, DN; Berlin, Y; Marusić, R; Prelog, V (1971). "Structure of boromycin". HelveticaChimica Acta 54 (6): 1709–1713. doi:10.1002/hlca.19710540624. PMID 5131791.

[98] Mahler, R. L.. "Essential Plant Micronutrients. Boron in Idaho" (http:/ / info. ag. uidaho. edu/ Resources/ PDFs/ CIS1085. pdf). Universityof Idaho. . Retrieved 2009-05-05.

[99] "Functions of Boron in Plant Nutrition" (http:/ / www. borax. com/ agriculture/ files/ an203. pdf) (PDF). U.S. Borax Inc.. .[100] Blevins, Dale G.; Lukaszewski, KM (1998). "Functions of Boron in Plant Nutrition". Annual Review of Plant Physiology and Plant

Molecular Biology 49: 481–500. doi:10.1146/annurev.arplant.49.1.481. PMID 15012243.[101] Nielsen, Forrest H. (1998). "Ultratrace elements in nutrition: Current knowledge and speculation". The Journal of Trace Elements in

Experimental Medicine 11 (2–3): 251–274. doi:10.1002/(SICI)1520-670X(1998)11:2/3<251::AID-JTRA15>3.0.CO;2-Q.[102] "Boron" (http:/ / web. archive. org/ web/ 20080524054321/ http:/ / www. pdrhealth. com/ drug_info/ nmdrugprofiles/ nutsupdrugs/

bor_0040. shtml). PDRhealth. Archived from the original (http:/ / www. pdrhealth. com/ drug_info/ nmdrugprofiles/ nutsupdrugs/ bor_0040.shtml) on 24 May 2008. . Retrieved 2008-09-18.

[103] Zook, E. G. (1965). "Total boron". J. Assoc. Off Agric. Chem 48: 850.[104] United States. Environmental Protection Agency. Office of Water, U. S. Environmental Protection Agency Staff (1993). Health advisories

for drinking water contaminants: United States Environmental Protection Agency Office of Water health advisories (http:/ / books. google.com/ ?id=trUdm-GXchIC& pg=PA84). CRC Press. p. 84. ISBN 087371931X. .

[105] Silverman, L.; Trego, Katherine (1953). "Corrections-Colorimetric Microdetermination of Boron By The Curcumin-Acetone SolutionMethod". Anal. Chem. 25 (11): 1639. doi:10.1021/ac60083a061.

[106] "Boric acid" (http:/ / chemicalland21. com/ industrialchem/ inorganic/ BORIC ACID. htm). . Retrieved 2009-05-05.[107] Overview of neutron capture therapy pharmaceuticals. (http:/ / www. pharmainfo. net/ reviews/ boron-neutron-capture-therapy-overview)[108] Travers, Richard L.; Rennie, George; Newnham, Rex (1990). "Boron and Arthritis: The Results of a Double-blind Pilot Study". Journal of

Nutritional & Environmental Medicine 1 (2): 127–132. doi:10.3109/13590849009003147.[109] Bonvini P, Zorzi E, Basso G, Rosolen A (2007). "Bortezomib-mediated 26S proteasome inhibition causes cell-cycle arrest and induces

apoptosis in CD-30+ anaplastic large cell lymphoma". Leukemia 21 (4): 838–42. doi:10.1038/sj.leu.2404528. PMID 17268529.[110] Garrett, Donald E. (1998). Borates (http:/ / books. google. com/ ?id=imMJJP5T5rsC& pg=PA385). Academic Press. p. 385.

ISBN 0122760603. .[111] "Environmental Health Criteria 204: Boron" (http:/ / www. inchem. org/ documents/ ehc/ ehc/ ehc204. htm). the IPCS. 1998. . Retrieved

2009-05-05.[112] Vithana, En; Morgan, P; Sundaresan, P; Ebenezer, Nd; Tan, Dt; Mohamed, Md; Anand, S; Khine, Ko; Venkataraman, D; Yong, Vh;

Salto-Tellez, M; Venkatraman, A; Guo, K; Hemadevi, B; Srinivasan, M; Prajna, V; Khine, M; Casey, Jr; Inglehearn, Cf; Aung, T (July 2006)."Mutations in sodium-borate cotransporter SLC4A11 cause recessive congenital hereditary endothelial dystrophy (CHED2)". Nature genetics38 (7): 755–7. doi:10.1038/ng1824. ISSN 1061-4036. PMID 16767101.

External links• The Periodic Table of Videos video of Boron (http:/ / www. youtube. com/ ?v=JzqdHkpXuy4) at YouTube• Boron (http:/ / www. du. edu/ ~jcalvert/ phys/ boron. htm)• WebElements.com – Boron (http:/ / www. webelements. com/ boron/ )• National Pollutant Inventory – Boron and compounds (http:/ / www. npi. gov. au/ database/ substance-info/

profiles/ 15. html)

Aluminium 31

Aluminium

Aluminium

Appearance

silvery gray metallic

Spectral lines of aluminium

General properties

Name, symbol, number aluminium, Al, 13

Pronunciation UK i/ˌæljʉˈmɪniəm/al-ew-min-ee-əm; or US i/əˈluːmɪnəm/ə-loo-mi-nəm

Element category other metal

Group, period, block 13, 3, p

Standard atomic weight 26.9815386(13) g·mol−1

Electron configuration [Ne] 3s2 3p1

Electrons per shell 2, 8, 3 (Image)

Physical properties

Phase solid

Density (near r.t.) 2.70 g·cm−3

Liquid density at m.p. 2.375 g·cm−3

Melting point 933.47 K,660.32 °C,1220.58 °F

Boiling point 2792 K,2519 °C,4566 °F

Heat of fusion 10.71 kJ·mol−1

Heat of vaporization 294.0 kJ·mol−1

Specific heat capacity (25 °C) 24.200 J·mol−1·K−1

Vapor pressure

P/Pa 1 10 100 1 k 10 k 100 k

at T/K 1482 1632 1817 2054 2364 2790

Atomic properties

Oxidation states 3, 2[1] , 1[2]

(amphoteric oxide)

Aluminium 32

Electronegativity 1.61 (Pauling scale)

Ionization energies(more)

1st: 577.5 kJ·mol−1

2nd: 1816.7 kJ·mol−1

3rd: 2744.8 kJ·mol−1

Atomic radius 143 pm

Covalent radius 121±4 pm

Van der Waals radius 184 pm

Miscellanea

Crystal structure face-centered cubic

Magnetic ordering paramagnetic[3]

Electrical resistivity (20 °C) 28.2 nΩ·m

Thermal conductivity (300 K) 237 W·m−1·K−1

Thermal expansion (25 °C) 23.1 µm·m−1·K−1

Speed of sound (thin rod) (r.t.) (rolled) 5,000 m·s−1

Young's modulus 70 GPa

Shear modulus 26 GPa

Bulk modulus 76 GPa

Poisson ratio 0.35

Mohs hardness 2.75

Vickers hardness 167 MPa

Brinell hardness 245 MPa

CAS registry number 7429-90-5

Most stable isotopes

iso NA half-life DM DE (MeV) DP

26Al trace 7.17×105y β+ 1.17 26Mg

ε - 26Mg

γ 1.8086 -

27Al 100% 27Al is stable with 14 neutron

Aluminium or aluminum (US English) is a silvery white member of the boron group of chemical elements. It hasthe symbol Al, and its atomic number is 13. It is not soluble in water under normal circumstances. Aluminium is thethird most abundant element (after oxygen and silicon), and the most abundant metal, in the Earth's crust. It makesup about 8% by weight of the Earth's solid surface. Aluminium metal is too reactive chemically to occur natively.Instead, it is found combined in over 270 different minerals.[4] The chief ore of aluminium is bauxite.Aluminium is remarkable for the metal's low density and for its ability to resist corrosion due to the phenomenon ofpassivation. Structural components made from aluminium and its alloys are vital to the aerospace industry and areimportant in other areas of transportation and structural materials. The most useful compounds of aluminium, at leaston a weight basis, are the oxides and sulfates.

Aluminium 33

Despite its prevalence in the environment, aluminium salts are not known to be used by any form of life. In keepingwith its pervasiveness, it is well tolerated by plants and animals.[5] Because of their prevalence, potential biologicalroles, beneficial and otherwise, aluminium compounds are of continuing interest.

Characteristics

Etched surface from a high purity (99.9998%)aluminium bar, size 55×37 mm

Physical

Aluminium is a soft, durable, lightweight, ductile and malleable metalwith appearance ranging from silvery to dull gray, depending on thesurface roughness. Aluminium is nonmagnetic and does not easilyignite. A fresh film of aluminium film serves as a good reflector(approximately 92%) of visible light and an excellent reflector (asmuch as 98%) of medium and far infrared radiation. The yield strengthof pure aluminium is 7–11 MPa, while aluminium alloys have yieldstrengths ranging from 200 MPa to 600 MPa.[6] Aluminium has aboutone-third the density and stiffness of steel. It is easily machined, cast,

drawn and extruded.

Corrosion resistance can be excellent due to a thin surface layer of aluminium oxide that forms when the metal isexposed to air, effectively preventing further oxidation. The strongest aluminium alloys are less corrosion resistantdue to galvanic reactions with alloyed copper.[6] This corrosion resistance is also often greatly reduced when manyaqueous salts are present, particularly in the presence of dissimilar metals.Aluminium atoms are arranged in a face-centered cubic (fcc) structure. Aluminium has a stacking-fault energy ofapproximately 200 mJ/m2.[7]

Aluminium is one of the few metals that retain full silvery reflectance in finely powdered form, making it animportant component of silver-colored paints. Aluminium mirror finish has the highest reflectance of any metal inthe 200–400 nm (UV) and the 3,000–10,000 nm (far IR) regions; in the 400–700 nm visible range it is slightlyoutperformed by tin and silver and in the 700–3000 (near IR) by silver, gold, and copper.[8]

Aluminium is a good thermal and electrical conductor, having 59% the conductivity of copper, both thermal andelectrical. Aluminium is capable of being a superconductor, with a superconducting critical temperature of 1.2Kelvin and a critical magnetic field of about 100 gauss (10 milliteslas).[9]

CreationStable aluminium is created when hydrogen fuses with magnesium either in large stars or in supernovae.[10]

IsotopesAluminium has many known isotopes, whose mass numbers range from 21 to 43; however, only 27Al (stable isotope) and 26Al (radioactive isotope, t1/2 = 7.2×105 y) occur naturally. 27Al has a natural abundance above 99.9%. 26Al is produced from argon in the atmosphere by spallation caused by cosmic-ray protons. Aluminium isotopes have found practical application in dating marine sediments, manganese nodules, glacial ice, quartz in rock exposures, and meteorites. The ratio of 26Al to 10Be has been used to study the role of transport, deposition, sediment storage, burial times, and erosion on 105 to 106 year time scales.[11] Cosmogenic 26Al was first applied in studies of the Moon and meteorites. Meteoroid fragments, after departure from their parent bodies, are exposed to intense cosmic-ray bombardment during their travel through space, causing substantial 26Al production. After falling to Earth, atmospheric shielding drastically reduces 26Al production, and its decay can then be used to determine the meteorite's terrestrial age. Meteorite research has also shown that 26Al was relatively abundant at the time of

Aluminium 34

formation of our planetary system. Most meteorite scientists believe that the energy released by the decay of 26Alwas responsible for the melting and differentiation of some asteroids after their formation 4.55 billion years ago.[12]

Natural occurrenceIn the Earth's crust, aluminium is the most abundant (8.3% by weight) metallic element and the third most abundantof all elements (after oxygen and silicon).[13] Because of its strong affinity to oxygen, it is almost never found in theelemental state; instead it is found in oxides or silicates. Feldspars, the most common group of minerals in the Earth'scrust, are aluminosilicates. Native aluminium metal can be found as a minor phase in low oxygen fugacityenvironments, such as the interiors of certain volcanoes.[14] Native aluminium has been reported in cold seeps in thenortheastern continental slope of the South China Sea and Chen et al. (2011)[15] have proposed a theory of its originas resulting by reduction from tetrahydroxoaluminate Al(OH)4

– to metallic aluminium by bacteria.[15]

It also occurs in the minerals beryl, cryolite, garnet, spinel and turquoise. Impurities in Al2O3, such as chromium oriron yield the gemstones ruby and sapphire, respectively.Although aluminium is an extremely common and widespread element, the common aluminium minerals are noteconomic sources of the metal. Almost all metallic aluminium is produced from the ore bauxite (AlOx(OH)3–2x).Bauxite occurs as a weathering product of low iron and silica bedrock in tropical climatic conditions.[16] Largedeposits of bauxite occur in Australia, Brazil, Guinea and Jamaica and the primary mining areas for the ore are inAustralia, Brazil, China, India, Guinea, Indonesia, Jamaica, Russia and Surinam.

Production and refinement

Bauxite, a major aluminium ore. The red-browncolour is due to the presence of iron minerals.

Aluminium forms strong chemical bonds with oxygen. Compared tomost other metals, it is difficult to extract from ore, such as bauxite,due to the energy required to reduce aluminium oxide (Al2O3). Forexample, direct reduction with carbon, as is used to produce iron, is notchemically possible because aluminium is a stronger reducing agentthan carbon. Indirect carbothermic reduction can be carried out usingcarbon and Al2O3, which forms an intermediate Al4C3 and this canfurther yield aluminium metal at a temperature of 1900–2000 °C. Thisprocess is still under development; it requires less energy and yieldsless CO2 than the Hall-Héroult process, the major industrial process foraluminium extraction.[17] Because of the high melting point ofaluminium oxide (about 2000 °C (3600 °F)) the pure metal is extractedby electrolysis. In this process, aluminium oxide is dissolved in molten cryolite with calcium fluoride and thenreduced to aluminium at a temperature between 950 and 980 °C (1,740 to 1,800 °F). Cryolite is a chemicalcompound of aluminium and sodium fluorides: (Na3AlF6). Although cryolite is found as a mineral in Greenland, itssynthetic form is used in the industry. The aluminium oxide is obtained by refining bauxite in the Bayer process.

The electrolytic process replaced the Wöhler process, which involved the reduction of anhydrous aluminium chloridewith potassium. Both of the electrodes used in the electrolysis of aluminium oxide are carbon. Once the refinedalumina is dissolved in the electrolyte, its ions are free to move around. The reaction at the cathode is:

Al3+ + 3 e− → AlHere the aluminium ion is being reduced. The aluminium metal then sinks to the bottom and is tapped off, usuallycast into large blocks called aluminium billets for further processing.At the anode, oxygen is formed:

2 O2− → O2 + 4 e−

Aluminium 35

To some extent, the carbon anode is degraded by the oxygen. The anodes in a reduction cell must therefore bereplaced regularly, since they are consumed in the process. The cathodes do erode, mainly due to electrochemicalprocesses and metal movement. After five to ten years, depending on the current used in the electrolysis, a cell has tobe rebuilt because of cathode wear.

World production trend of aluminium

Aluminium electrolysis with the Hall-Héroult process consumes a lotof energy, but alternative processes were always found to be less viableeconomically and/or ecologically. The worldwide average specificenergy consumption is approximately 15±0.5 kilowatt-hours perkilogram of aluminium produced (52 to 56 MJ/kg). The most modernsmelters achieve approximately 12.8 kW·h/kg (46.1 MJ/kg). (Comparethis to the heat of reaction, 31 MJ/kg, and the Gibbs free energy ofreaction, 29 MJ/kg.) Reduction line currents for older technologies aretypically 100 to 200 kiloamperes; state-of-the-art smelters operate atabout 350 kA. Trials have been reported with 500 kA cells.

The Hall-Heroult process produces aluminium with a purity of above 99%. Further purification can be done by theHoope process. The process involves the electrolysis of molten aluminium with a sodium, barium and aluminiumfluoride electrolyte. The resulting aluminium has a purity of 99.99%.[18] [19]

Electric power represents about 20% to 40% of the cost of producing aluminium, depending on the location of thesmelter. Aluminium production consumes roughly 5% of electricity generated in the U.S.[20] Smelters tend to besituated where electric power is both plentiful and inexpensive, such as the United Arab Emirates with excess naturalgas supplies and Iceland and Norway with energy generated from renewable sources. The world's largest smelters ofalumina are People's Republic of China, Russia, and Quebec and British Columbia in Canada.[20] [21] [22]

Aluminium output in 2005

In 2005, the People's Republic of China was the top producer ofaluminium with almost a one-fifth world share, followed by Russia,Canada, and the USA, reports the British Geological Survey.

Over the last 50 years, Australia has become a major producer ofbauxite ore and a major producer and exporter of alumina (beforebeing overtaken by China in 2007).[21] [23] Australia produced 62million tonnes of bauxite in 2005. The Australian deposits have somerefining problems, some being high in silica, but have the advantage of being shallow and relatively easy to mine.[24]

Recycling

Aluminium recycling code

Aluminium is theoretically 100% recyclable without any loss of its naturalqualities. According to the International Resource Panel's Metal Stocks inSociety report, the global per capita stock of aluminium in use in society (i.e.in cars, buildings, electronics etc.) is 80 kg. Much of this is inmore-developed countries (350–500 kg per capita) rather than less-developedcountries (35 kg per capita). Knowing the per capita stocks and theirapproximate lifespans is important for planning recycling.

Recovery of the metal via recycling has become an important facet of thealuminium industry. Recycling was a low-profile activity until the late 1960s,when the growing use of aluminium beverage cans brought it to the publicawareness.

Aluminium 36

Recycling involves melting the scrap, a process that requires only 5% of the energy used to produce aluminium fromore, though a significant part (up to 15% of the input material) is lost as dross (ash-like oxide).[25] The dross canundergo a further process to extract aluminium.In Europe aluminium experiences high rates of recycling, ranging from 42% of beverage cans, 85% of constructionmaterials and 95% of transport vehicles.[26]

Recycled aluminium is known as secondary aluminium, but maintains the same physical properties as primaryaluminium. Secondary aluminium is produced in a wide range of formats and is employed in 80% of alloy injections.Another important use is for extrusion.White dross from primary aluminium production and from secondary recycling operations still contains usefulquantities of aluminium that can be extracted industrially.[27] The process produces aluminium billets, together witha highly complex waste material. This waste is difficult to manage. It reacts with water, releasing a mixture of gases(including, among others, hydrogen, acetylene, and ammonia), which spontaneously ignites on contact with air;[28]

contact with damp air results in the release of copious quantities of ammonia gas. Despite these difficulties, thewaste has found use as a filler in asphalt and concrete.[29]

Compounds

Oxidation state +3The vast majority of compounds, including all Al-containing minerals and all commercially significant aluminiumcompounds, feature aluminium in the oxidation state 3+. The coordination number of such compounds varies, butgenerally Al3+ is six-coordinate or tetracoordinate. Almost all compounds of aluminium(III) are colorless.[13]

Halides

All four trihalides are well known. Unlike the structures of the three heavier trihalides, aluminium fluoride (AlF3)features six-coordinate Al. The octahedral coordination environment for AlF3 is related to the compactness offluoride ion, six of which can fit around the small Al3+ centre. AlF3 sublimes (with cracking) at 1291 °C (2356 °F).With heavier halides, the coordination numbers are lower. The other trihalides are dimeric or polymeric withtetrahedral Al centers. These materials are prepared by treating aluminium metal with the halogen, although othermethods exist. Acidification of the oxides or hydroxides affords hydrates. In aqueous solution, the halides often formmixtures, generally containing six-coordinate Al centres, which are feature both halide and aquo ligands. Whenaluminium and fluoride are together in aqueous solution, they readily form complex ions such as [AlF(H2O)5]2+,AlF3(H2O)3, and [AlF6]3−. In the case of chloride, polyaluminium clusters are formed such as[Al13O4(OH)24(H2O)12]7+.

Oxide and hydroxides

Aluminium forms one stable oxide, known by its mineral name corundum. Sapphire and ruby are impure corundumcontaminated with trace amounts of other metals. The two oxide-hydroxides (AlO(OH) are boehmite and diaspore.There are three trihydroxides: bayerite, gibbsite, and nordstrandite, which differ in their crystalline structure(polymorphs). Most are produced from ores by a variety of wet processes using acid and base. Heating thehydroxides leads to formation of corundrum. These materials are of central importance to the production ofaluminium and are themselves extremely useful.

Aluminium 37

Carbide, nitride, and related materials

Aluminium carbide (Al4C3) is made by heating a mixture of the elements above 1000 °C (1832 °F). The pale yellowcrystals consist of tetrahedral aluminium centres. It reacts with water or dilute acids to give methane. The acetylide,Al2(C2)3, is made by passing acetylene over heated aluminium.Aluminium nitride (AlN) is the only nitride known for aluminium. Unlike the oxides it features tetrahedral Alcentres. It can be made from the elements at 800 °C (1472 °F). It is air-stable material with a usefully high thermalconductivity. Aluminium phosphide (AlP) is made similarly, and hydrolyses to give phosphine:

AlP + 3 H2O → Al(OH)3 + PH3

Organoaluminium compounds and related hydrides

Structure of trimethylaluminium, a compound that featuresfive-coordinate carbon.

A variety of compounds of empirical formula AlR3 andAlR1.5Cl1.5 exist.[30] These species usually feature tetrahedralAl centres, e.g. "trimethylaluminium" has the formulaAl2(CH3)6 (see figure). With large organic groups,triorganoaluminium exist as three-coordinate monomers, suchas triisobutylaluminium. Such compounds are widely used inindustrial chemistry, despite the fact that they are often highlypyrophoric. Few analogues exist between organoaluminiumand organoboron compounds except for large organic groups.

The important aluminium hydride is lithium aluminiumhydride (LiAlH4), which is used in as a reducing agent inorganic chemistry. It can be produced from lithium hydrideand aluminium trichloride:

4 LiH + AlCl3 → LiAlH4 + 3 LiClSeveral useful derivatives of LiAlH4 are known, e.g. Sodium bis(2-methoxyethoxy)dihydridoaluminate. The simplesthydride, aluminium hydride or alane, remains a laboratory curiosity. It is a polymer with the formula (AlH3)n, incontrast to the corresponding boron hydride with the formula (BH3)2.

Oxidation states +1 and +2Although the great majority of aluminium compounds feature Al3+ centres, compounds with lower oxidation statesare known and sometime of significance as precursors to the Al3+ species.

Aluminium(I)

AlF, AlCl and AlBr exist in the gaseous phase when the tri-halide is heated with aluminium. The composition AlI isunstable at room temperature with respect to the triiodide:[31]

3 AlI → AlI3 + 2 AlA stable derivative of aluminium monoiodide is the cyclic adduct formed with triethylamine, Al4I4(NEt3)4. Also oftheoretical interest but only of fleeting existence are Al2O and Al2S is made by heating the normal oxide, Al2O3,with silicon at 1800 °C (3272 °F) in a vacuum.[31] Such materials quickly disproportionates to the starting materials.

Aluminium 38

Aluminium(II)

Very simple Al(II) compounds are invoked or observed in the reactions of Al metal with oxidants. For example,aluminium monoxide, AlO, has been detected in the gas phase after explosion[32] and in stellar absorption spectra.[33]

More thoroughly investigated are compounds of the formula R4Al2 where R is a large organic ligand.[34]

AnalysisThe presence of aluminium can be detected in qualitative analysis using aluminon.

Applications

General useAluminium is the most widely used non-ferrous metal.[35] Global production of aluminium in 2005 was 31.9 milliontonnes. It exceeded that of any other metal except iron (837.5 million tonnes).[36] Forecast for 2012 is 42–45 milliontonnes, driven by rising Chinese output.[37]

Aluminium is almost always alloyed, which markedly improves its mechanical properties, especially whentempered. For example, the common aluminium foils and beverage cans are alloys of 92% to 99% aluminium.[38]

The main alloying agents are copper, zinc, magnesium, manganese, and silicon (e.g., duralumin) and the levels ofthese other metals are in the range of a few percent by weight.[39]

Household aluminium foil

Aluminium-bodied Austin "A40 Sports" (circa1951)

Some of the many uses for aluminium metal are in:• Transportation (automobiles, aircraft, trucks, railway cars, marine

vessels, bicycles, etc.) as sheet, tube, castings, etc.• Packaging (cans, foil, etc.)• Construction (windows, doors, siding, building wire, etc.).[40]

• A wide range of household items, from cooking utensils to baseballbats, watches.[41]

• Street lighting poles, sailing ship masts, walking poles, etc.• Outer shells of consumer electronics, also cases for equipment e.g.

photographic equipment.• Electrical transmission lines for power distribution• MKM steel and Alnico magnets• Super purity aluminium (SPA, 99.980% to 99.999% Al), used in

electronics and CDs.• Heat sinks for electronic appliances such as transistors and CPUs.• Substrate material of metal-core copper clad laminates used in high

brightness LED lighting.• Powdered aluminium is used in paint, and in pyrotechnics such as

solid rocket fuels and thermite.• Aluminium can be reacted with hydrochloric acid or with sodium

hydroxide to produce hydrogen gas.• A variety of countries, including France, Italy, Poland, Finland,

Romania, Israel, and the former Yugoslavia, have issued coins struck in aluminium or aluminium-copperalloys.[42]

Aluminium 39

Aluminium slabs being transported from asmelter

• Some guitar models sports aluminium diamond plates on the surfaceof the instruments, usually either chrome or black. Kramer Guitarsand Travis Bean are both known for having produced guitars withnecks made of aluminium, which gives the instrument a verydistinct sound.

Aluminium is usually alloyed – it is used as pure metal only whencorrosion resistance and/or workability is more important than strengthor hardness. A thin layer of aluminium can be deposited onto a flatsurface by physical vapour deposition or (very infrequently) chemicalvapour deposition or other chemical means to form optical coatingsand mirrors.

Aluminium compoundsBecause aluminium is abundant and most of its derivative exhibit low toxicity, the compounds of aluminium enjoywide and sometimes large-scale applications.

Alumina

Aluminium oxide (Al2O3) and the associated oxy-hydroxides and trihydroxides are produced or extracted fromminerals on a large scale. The great majority of this material is converted to metallic aluminium. About 10% of theproduction capacity is used for other applications. A major use is as an absorbent, for example alumina will removewater from hydrocarbons, to enable subsequent processes that are poisoned by moisture. Aluminium oxides arecommon catalysts for industrial processes, e.g. the Claus process for converting hydrogen sulfide to sulfur inrefineries and for the alkylation of amines. Many industrial catalysts are "supported", meaning generally that anexpensive catalyst (e.g., platinum) is dispersed over a high surface area material such as alumina. Being a very hardmaterial (Mohs hardness 9), alumina is widely used as an abrasive and the production of applications that exploit itsinertness, e.g., in high pressure sodium lamps.

Sulfates

Several sulfates of aluminium find applications. Aluminium sulfate (Al2(SO4)3(H2O)18) is produced on the annualscale of several billions of kilograms. About half of the production is consumed in water treatment. The next majorapplication is in the manufacture of paper. It is also used as a mordant, in fire extinguisher, as a food additive, infireproofing, and in leather tanning. Aluminium ammonium sulfate, which is also called ammonium alum,(NH4)Al(SO4)2·12H2O, is used as a mordant and in leather tanning.[5] Aluminium potassium sulfate([Al(K)](SO4)2)(H2O)12 is used similarly. The consumption of both alums is declining.

Chlorides

Aluminium chloride (AlCl3) is used in petroleum refining and in the production of synthetic rubber and polymers.Although it has a similar name, aluminium chlorohydrate has fewer and very different applications, e.g. as anhardening agent and an antiperspirant. It is an intermediate in the production of aluminium metal.

Niche compounds

Given the scale of aluminium compounds, a small scale application could still involve thousands of tonnes. One of the many compounds used at this intermediate level include aluminium acetate, a salt used in solution as an astringent. Aluminium borate (Al2O3·B2O3) is used in the production of glass and ceramics. Aluminium fluorosilicate (Al2(SiF6)3) is used in the production of synthetic gemstones, glass and ceramic. Aluminium phosphate (AlPO4) is used in the manufacture: of glass and ceramic, pulp and paper products, cosmetics, paints and varnishes

Aluminium 40

and in making dental cement. Aluminium hydroxide (Al(OH)3) is used as an antacid, as a mordant, in waterpurification, in the manufacture of glass and ceramic and in the waterproofing of fabrics. Lithium aluminium hydrideis a powerful reducing agent used in organic chemistry. Organoaluminiums are used as Lewis acids and cocatalysts.For example, methylaluminoxane is a cocatalyst for Ziegler-Natta olefin polymerization to produce vinyl polymerssuch as polyethene.

Aluminium alloys in structural applications

Aluminium foam

Aluminium alloys with a wide range of properties are used inengineering structures. Alloy systems are classified by a numbersystem (ANSI) or by names indicating their main alloying constituents(DIN and ISO).

The strength and durability of aluminium alloys vary widely, not onlyas a result of the components of the specific alloy, but also as a resultof heat treatments and manufacturing processes. A lack of knowledgeof these aspects has from time to time led to improperly designedstructures and gained aluminium a bad reputation.One important structural limitation of aluminium alloys is their fatiguestrength. Unlike steels, aluminium alloys have no well-defined fatiguelimit, meaning that fatigue failure eventually occurs, under even verysmall cyclic loadings. This implies that engineers must assess theseloads and design for a fixed life rather than an infinite life.

Another important property of aluminium alloys is their sensitivity toheat. Workshop procedures involving heating are complicated by thefact that aluminium, unlike steel, melts without first glowing red. Forming operations where a blow torch is usedtherefore require some expertise, since no visual signs reveal how close the material is to melting. Aluminium alloys,like all structural alloys, also are subject to internal stresses following heating operations such as welding andcasting. The problem with aluminium alloys in this regard is their low melting point, which make them moresusceptible to distortions from thermally induced stress relief. Controlled stress relief can be done duringmanufacturing by heat-treating the parts in an oven, followed by gradual cooling—in effect annealing the stresses.

The low melting point of aluminium alloys has not precluded their use in rocketry; even for use in constructingcombustion chambers where gases can reach 3500 K. The Agena upper stage engine used a regeneratively cooledaluminium design for some parts of the nozzle, including the thermally critical throat region.Another alloy of some value is aluminium bronze (Cu-Al alloy).

Aluminium 41

History

The statue of the Anteros (commonly mistakenfor either The Angel of Christian Charity or Eros)in Piccadilly Circus, London, was made in 1893

and is one of the first statues to be cast inaluminium.

Ancient Greeks and Romans used aluminium salts as dyeing mordantsand as astringents for dressing wounds; alum is still used as a styptic.In 1761, Guyton de Morveau suggested calling the base alum alumine.In 1808, Humphry Davy identified the existence of a metal base ofalum, which he at first termed alumium and later aluminum (seeetymology section, below).

The metal was first produced in 1825 in an impure form by Danishphysicist and chemist Hans Christian Ørsted. He reacted anhydrousaluminium chloride with potassium amalgam, yielding a lump of metallooking similar to tin.[43] Friedrich Wöhler was aware of theseexperiments and cited them, but after redoing the experiments ofØrsted he concluded that this metal was pure potassium. He conducteda similar experiment in 1827 by mixing anhydrous aluminium chloridewith potassium and yielded aluminium.[43] Wöhler is generallycredited with isolating aluminium (Latin alumen, alum), but alsoØrsted can be listed as its discoverer.[44] Further, Pierre Berthierdiscovered aluminium in bauxite ore and successfully extracted it.[45]

Frenchman Henri Etienne Sainte-Claire Deville improved Wöhler'smethod in 1846, and described his improvements in a book in 1859,chief among these being the substitution of sodium for theconsiderably more expensive potassium.[46] Deville likely alsoconceived the idea of the electrolysis of aluminium oxide dissolved in cryolite; Charles Martin Hall and Paul Héroultmight have developed the more practical process after Deville.

Before the Hall-Héroult process was developed in the late 1880s, aluminium was exceedingly difficult to extractfrom its various ores. This made pure aluminium more valuable than gold.[47] Bars of aluminium were exhibited atthe Exposition Universelle of 1855.[48] Napoleon III, Emperor of France, is reputed to have given a banquet wherethe most honoured guests were given aluminium utensils, while the others made do with gold.[49] [50]

Aluminium was selected as the material to be used for the 100 ounce (2.8 kg) capstone of the WashingtonMonument in 1884, a time when one ounce (30 grams) cost the daily wage of a common worker on the project;[51]

The capstone, which was set in place on December 6, 1884, in an elaborate dedication ceremony, was the largestsingle piece of aluminium cast at the time, when aluminium was as expensive as silver.[52]

The Cowles companies supplied aluminium alloy in quantity in the United States and England using smelters like thefurnace of Carl Wilhelm Siemens by 1886.[53] Charles Martin Hall of Ohio in the U.S. and Paul Héroult of Franceindependently developed the Hall-Héroult electrolytic process that made extracting aluminium from mineralscheaper and is now the principal method used worldwide. Hall's process,[54] in 1888 with the financial backing ofAlfred E. Hunt, started the Pittsburgh Reduction Company today known as Alcoa. Héroult's process was inproduction by 1889 in Switzerland at Aluminium Industrie, now Alcan, and at British Aluminium, now LuxferGroup and Alcoa, by 1896 in Scotland.[55]

By 1895, the metal was being used as a building material as far away as Sydney, Australia in the dome of the ChiefSecretary's Building.Many navies have used an aluminium superstructure for their vessels; the 1975 fire aboard USS Belknap that guttedher aluminium superstructure, as well as observation of battle damage to British ships during the Falklands War, ledto many navies switching to all steel superstructures. The Arleigh Burke class was the first such U.S. ship, beingconstructed entirely of steel.

Aluminium 42

Aluminium wire was once widely used for domestic electrical wiring. Owing to corrosion-induced failures, a numberof fires resulted. This discontinuation thus illustrates one failed application of the otherwise highly useful metal.In 2008, the price of aluminium peaked at $1.45/lb in July but dropped to $0.70/lb by December.[56]

EtymologyTwo variants of the metal's name are in current use, aluminium and aluminum (besides the obsolete alumium). TheInternational Union of Pure and Applied Chemistry (IUPAC) adopted aluminium as the standard international namefor the element in 1990 but, three years later, recognized aluminum as an acceptable variant. Hence their periodictable includes both.[57] IUPAC prefers the use of aluminium in its internal publications, although nearly as manyIUPAC publications use the spelling aluminum.[58]

Most countries use the spelling aluminium. In the United States, the spelling aluminum predominates.[13] [59] TheCanadian Oxford Dictionary prefers aluminum, whereas the Australian Macquarie Dictionary prefers aluminium. In1926, the American Chemical Society officially decided to use aluminum in its publications; American dictionariestypically label the spelling aluminium as a British variant.The name aluminium derives from its status as a base of alum. It is borrowed from Old French; its ultimate source,alumen, in turn is a Latin word that literally means "bitter salt".[60]

The earliest citation given in the Oxford English Dictionary for any word used as a name for this element isalumium, which British chemist and inventor Humphry Davy employed in 1808 for the metal he was trying to isolateelectrolytically from the mineral alumina. The citation is from the journal Philosophical Transactions of the RoyalSociety of London: "Had I been so fortunate as to have obtained more certain evidences on this subject, and to haveprocured the metallic substances I was in search of, I should have proposed for them the names of silicium, alumium,zirconium, and glucium."[61] [62]

Davy settled on aluminum by the time he published his 1812 book Chemical Philosophy: "This substance appears tocontain a peculiar metal, but as yet Aluminum has not been obtained in a perfectly free state, though alloys of it withother metalline substances have been procured sufficiently distinct to indicate the probable nature of alumina."[63]

But the same year, an anonymous contributor to the Quarterly Review, a British political-literary journal, in a reviewof Davy's book, objected to aluminum and proposed the name aluminium, "for so we shall take the liberty of writingthe word, in preference to aluminum, which has a less classical sound."[64]

The -ium suffix conformed to the precedent set in other newly discovered elements of the time: potassium, sodium,magnesium, calcium, and strontium (all of which Davy isolated himself). Nevertheless, -um spellings for elementswere not unknown at the time, as for example platinum, known to Europeans since the 16th century, molybdenum,discovered in 1778, and tantalum, discovered in 1802. The -um suffix is consistent with the universal spellingalumina for the oxide, as lanthana is the oxide of lanthanum, and magnesia, ceria, and thoria are the oxides ofmagnesium, cerium, and thorium respectively.The spelling used throughout the 19th century by most U.S. chemists was aluminium, but common usage is lessclear.[65] The aluminum spelling is used in the Webster's Dictionary of 1828. In his advertising handbill for his newelectrolytic method of producing the metal 1892, Charles Martin Hall used the -um spelling, despite his constant useof the -ium spelling in all the patents[54] he filed between 1886 and 1903.[66] It has consequently been suggested thatthe spelling reflects an easier to pronounce word with one fewer syllable, or that the spelling on the flier was amistake. Hall's domination of production of the metal ensured that the spelling aluminum became the standard inNorth America; the Webster Unabridged Dictionary of 1913, though, continued to use the -ium version.

Aluminium 43

Health concerns

NFPA 704

Fire diamond for aluminium shot

Despite its natural abundance, aluminium has no known function in biology. It is remarkably nontoxic, aluminiumsulfate having an LD50 of 6207 mg/kg (oral, mouse), which corresponds to 500 grams for a 80 kg person.[5] Despitethe extremely low acute toxicity, the health effects of aluminium are of interest in view of the widespread occurrenceof the element in the environment and in commerce.Some toxicity can be traced to deposition in bone and the central nervous system, which is particularly increased inpatients with reduced renal function. Because aluminium competes with calcium for absorption, increased amountsof dietary aluminium may contribute to the reduced skeletal mineralization (osteopenia) observed in preterm infantsand infants with growth retardation. In very high doses, aluminium can cause neurotoxicity, and is associated withaltered function of the blood-brain barrier.[67] A small percentage of people are allergic to aluminium and experiencecontact dermatitis, digestive disorders, vomiting or other symptoms upon contact or ingestion of products containingaluminium, such as deodorants or antacids. In those without allergies, aluminium is not as toxic as heavy metals, butthere is evidence of some toxicity if it is consumed in excessive amounts.[68] Although the use of aluminiumcookware has not been shown to lead to aluminium toxicity in general, excessive consumption of antacids containingaluminium compounds and excessive use of aluminium-containing antiperspirants provide more significant exposurelevels. Studies have shown that consumption of acidic foods or liquids with aluminium significantly increasesaluminium absorption,[69] and maltol has been shown to increase the accumulation of aluminium in nervous andosseus tissue.[70] Furthermore, aluminium increases estrogen-related gene expression in human breast cancer cellscultured in the laboratory.[71] The estrogen-like effects of these salts have led to their classification as ametalloestrogen.The effects of aluminium in antiperspirants has been examined over the course of decades with little evidence of skinirritation.[5] Nonetheless, its occurrence in antiperspirants, dyes (such as aluminium lake), and food additives iscontroversial in some quarters. Although there is little evidence that normal exposure to aluminium presents a risk tohealthy adults,[72] some studies point to risks associated with increased exposure to the metal.[73] Aluminium in foodmay be absorbed more than aluminium from water.[74] Some researchers have expressed concerns that thealuminium in antiperspirants may increase the risk of breast cancer,[75] and aluminium has controversially beenimplicated as a factor in Alzheimer's disease.[76] The Camelford water pollution incident involved a number ofpeople consuming aluminium sulfate. Investigations of the long-term health effects are still ongoing, but elevatedbrain aluminium concentrations have been found in post-mortem examinations of victims, and further research todetermine if there is a link with cerebral amyloid angiopathy has been commissioned.[77]

According to The Alzheimer's Society, the overwhelming medical and scientific opinion is that studies have notconvincingly demonstrated a causal relationship between aluminium and Alzheimer's disease.[78] Nevertheless, somestudies, such as those on the PAQUID cohort,[79] cite aluminium exposure as a risk factor for Alzheimer's disease.Some brain plaques have been found to contain increased levels of the metal.[80] Research in this area has beeninconclusive; aluminium accumulation may be a consequence of the disease rather than a causal agent. In any event,if there is any toxicity of aluminium, it must be via a very specific mechanism, since total human exposure to theelement in the form of naturally occurring clay in soil and dust is enormously large over a lifetime.[81] [82] Scientificconsensus does not yet exist about whether aluminium exposure could directly increase the risk of Alzheimer'sdisease.[78]

Aluminium 44

Effect on plantsAluminium is primary among the factors that reduce plant growth on acid soils. Although it is generally harmless toplant growth in pH-neutral soils, the concentration in acid soils of toxic Al3+ cations increases and disturbs rootgrowth and function.[83] [84] [85] [86]

Most acid soils are saturated with aluminium rather than hydrogen ions. The acidity of the soil is therefore a result ofhydrolysis of aluminium compounds.[87] This concept of "corrected lime potential"[88] to define the degree of basesaturation in soils became the basis for procedures now used in soil testing laboratories to determine the "limerequirement"[89] of soils.[90]

Wheat's adaptation to allow aluminium tolerance is such that the aluminium induces a release of organic compoundsthat bind to the harmful aluminium cations. Sorghum is believed to have the same tolerance mechanism. The firstgene for aluminium tolerance has been identified in wheat. It was shown that sorghum's aluminium tolerance iscontrolled by a single gene, as for wheat.[91] This is not the case in all plants.

References[1] Aluminium monoxide[2] Aluminium iodide[3] Magnetic susceptibility of the elements and inorganic compounds (http:/ / www-d0. fnal. gov/ hardware/ cal/ lvps_info/ engineering/

elementmagn. pdf), in Handbook of Chemistry and Physics 81st edition, CRC press.[4] Shakhashiri, Bassam Z.. "Chemical of the Week: Aluminum" (http:/ / scifun. chem. wisc. edu/ chemweek/ Aluminum/ ALUMINUM. html).

Science is Fun. . Retrieved 2007-08-28.[5] Otto Helmboldt, L. Keith Hudson, Chanakya Misra, Karl Wefers, Wolfgang Heck, Hans Stark, Max Danner, Norbert Rösch "Aluminum

Compounds, Inorganic" in Ullmann's Encyclopedia of Industrial Chemistry, 2007, Wiley-VCH, Weinheim.doi:10.1002/14356007.a01_527.pub2

[6] Polmear, I. J. (1995). Light Alloys: Metallurgy of the Light Metals. Arnold. ISBN 9780340632079.[7] Dieter G. E. (1988). Mechanical Metallurgy. McGraw-Hill. ISBN 0070168938.[8] Macleod, H. A. (2001). Thin-film optical filters. CRC Press. pp. 158–159. ISBN 0750306882.[9] Cochran, John F. and Mapother, D. E. (1958). "Superconducting Transition in Aluminum". Physical Review 111 (1): 132–142.

Bibcode 1958PhRv..111..132C. doi:10.1103/PhysRev.111.132.[10] Cameron, A.G.W. (1957). "Stellar Evolution, Nuclear Astrophysics, and Nucleogenesis" (http:/ / www. fas. org/ sgp/ eprint/ CRL-41. pdf).

CRL-41. .[11] "Cosmogenic Isotopes and Aluminum" (http:/ / www. onafarawayday. com/ Radiogenic/ Ch14/ Ch14-6. htm). .[12] Robert T. Dodd (1986). Thunderstones and Shooting Stars. Cambridge, Mass.: Harvard University Press. pp. 89–90. ISBN 0-674-89137-6.[13] Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Oxford: Butterworth-Heinemann.

ISBN 0080379419., p. 217[14] "Aluminum Mineral Data" (http:/ / webmineral. com/ data/ Aluminum. shtml). . Retrieved 2008-07-09.[15] Chen Z., Huang C.-Y., Zhao M., Yan W., Chien C.-W., Chen M., Yang H., Machiyama H. and Lin S. (2011). "Characteristics and possible

origin of native aluminum in cold seep sediments from the northeastern South China Sea". Journal of Asian Earth Sciences 40 (1): 363–370.doi:10.1016/j.jseaes.2010.06.006.

[16] Guilbert, John M. and Carles F. Park (1986). The Geology of Ore Deposits. Freeman. pp. 774–795. ISBN 0-7167-1456-6.[17] John A. S. Green (2007). Aluminum recycling and processing for energy conservation and sustainability (http:/ / books. google. com/

?id=t-Jg-i0XlpcC& pg=PA198). Materials Park, Ohio: ASM International. p. 198. ISBN 0871708590. .[18] William B. Frank, Warren E. Haupin, Robert K. Dawless, Douglas A. Granger, Maurice W. Wei, Kenneth J. Calhoun, Thomas B. Bonney

"Aluminum" in Ullmann's Encyclopedia of Industrial Chemistry, 2009, Wiley-VCH, Weinheim. doi:10.1002/14356007.a01_459.pub2[19] Totten, George E; Scott Mackenzie, D; Comercial), Marcel Dekker (Firma (2003-04-25). Handbook of aluminum: Alloy production and

materials manufacturing (http:/ / books. google. de/ books?id=KpgTrFloOq0C& pg=PA40). p. 40. ISBN 9780824748432. .[20] Emsley, John (2001). "Aluminium" (http:/ / books. google. com/ ?id=j-Xu07p3cKwC& pg=PA24). Nature's Building Blocks: An A-Z Guide

to the Elements. Oxford, UK: Oxford University Press. p. 24. ISBN 0198503407. .[21] British Geological Survey (2009). World Mineral Production 2003–2007 (http:/ / www. bgs. ac. uk/ downloads/ start. cfm?id=1388). .[22] Christoph Schmitz, Josef Domagala, Petra Haag (2006). Handbook of aluminium recycling: fundamentals, mechanical preparation,

metallurgical processing, plant design. Vulkan-Verlag GmbH. p. 27. ISBN 3802729366.[23] "The Australian Industry" (http:/ / web. archive. org/ web/ 20070717041628/ http:/ / www. aluminium. org. au/ Page. php?s=1005).

Australian Aluminium Council. Archived from the original (http:/ / www. aluminium. org. au/ Page. php?s=1005) on 2007-07-17. . Retrieved2007-08-11.

Aluminium 45

[24] "Australian Bauxite" (http:/ / web. archive. org/ web/ 20070718172244/ http:/ / www. aluminium. org. au/ Page. php?s=1007). AustralianAluminium Council. Archived from the original (http:/ / www. aluminium. org. au/ Page. php?s=1007) on 2007-07-18. . Retrieved2007-08-11.

[25] "Benefits of Recycling" (http:/ / web. archive. org/ web/ 20030624162738/ http:/ / www. dnr. state. oh. us/ recycling/ awareness/ facts/benefits. htm). Ohio Department of Natural Resources. .

[26] "Reciclado del aluminio. Confemetal.es ASERAL" (http:/ / web. archive. org/ web/ 20110720135925/ http:/ / www. confemetal. es/ aseral/recuperacion. htm). .

[27] Hwang, J.Y., Huang, X., Xu, Z. (2006). "Recovery of Metals from Aluminium Dross and Salt cake". Journal of Minerals & MaterialsCharacterization & Engineering 5: 47.

[28] "Why are dross & saltcake a concern?" (http:/ / www. ohiolandfills. org/ ?page_id=34). .[29] Dunster, A.M., Moulinier, F., Abbott, B., Conroy, A., Adams, K., Widyatmoko, D.(2005). Added value of using new industrial waste

streams as secondary aggregates in both concrete and asphalt. DTI/WRAP Aggregates Research Programme STBF 13/15C. The Waste andResources Action Programme.

[30] Elschenbroich, C. ”Organometallics” (2006) Wiley-VCH: Weinheim. ISBN 978-3-29390-6[31] Dohmeier, C.; Loos, D.; Schnöckel, H. (1996). "Aluminum(I) and Gallium(I) Compounds: Syntheses, Structures, and Reactions".

Angewandte Chemie International Edition 35 (2): 129. doi:10.1002/anie.199601291.[32] Tyte, D. C. (1964). "Red (B2Π–A2σ) Band System of Aluminium Monoxide". Nature 202 (4930): 383. Bibcode 1964Natur.202..383T.

doi:10.1038/202383a0.[33] Merrill, P. W., Deutsch, A. J., & Keenan, P. C. (1962). "Absorption Spectra of M-Type Mira Variables". Astrophysical Journal 136: 21.

Bibcode 1962ApJ...136...21M. doi:10.1086/147348.[34] Werner Uhl, "Organoelement Compounds Possessing Al—Al, Ga—Ga, In—In, and Tl—Tl Single Bonds" Advances in Organometallic

Chemistry Volume 51, 2004, pp. 53–108. doi:10.1016/S0065-3055(03)51002-4[35] "aluminum" (http:/ / www. britannica. com/ eb/ art-64454). Encyclopædia Britannica. .[36] Hetherington, L E et al. (2007). World Mineral Production: 2001–2005 (http:/ / www. bgs. ac. uk/ downloads/ start. cfm?id=1417). British

Geological Survey. ISBN 978-0-85272-592-4. .[37] Rising Chinese Costs to Support Aluminum Prices (http:/ / www. bloomberg. com/ apps/ news?pid=20602013& sid=avBxcmX9rI1Y)

Bloomberg News, November 23, 2009[38] Millberg, L. S.. "Aluminum Foil" (http:/ / www. madehow. com/ Volume-1/ Aluminum-Foil. html). How Products are Made. . Retrieved

2007-08-11.[39] J. Paul Lyle, Douglas A. Granger, Robert E. Sanders, "Aluminum Alloys" Ullmann's Encyclopedia of Industrial Chemistry, 2005,

Wiley-VCH, Weinheim. doi:10.1002/14356007.a01_481[40] Sustainability of Aluminium in Buildings (http:/ / web. archive. org/ web/ 20030624162738/ http:/ / www. dnr. state. oh. us/ recycling/

awareness/ facts/ benefits. htm). European Aluminium Association[41] "Aluminum in Watchmaking" (http:/ / watches. infoniac. com/ index. php?page=post& id=62). . Retrieved 2009-06-06.[42] "World's coinage uses 24 chemical elements", 2 part series, World Coin News (February 17, 1992 and March 2, 1992)[43] Wöhler, Friedrich. "Ueber das Aluminium" (http:/ / gallica. bnf. fr/ ark:/ 12148/ bpt6k150967/ f158. table). Annalen der Physik und Chemie.

.[44] Bentor, Yinon. "Periodic Table: Aluminum" (http:/ / www. chemicalelements. com/ elements/ al. html). ChemicalElements.com. . Retrieved

2007-08-11.[45] "Pierre Berthier" (http:/ / www. todayinsci. com/ 7/ 7_03. htm#Berthier). Today in Science History. . Retrieved 2007-08-11.[46] Henri Etienne Sainte-Claire Deville De l'aluminium, ses propriétés, sa fabrication (http:/ / books. google. com/

books?id=rCoKAAAAIAAJ) (Paris, 1859)[47] Polmear, I.J. (2006). "Production of Aluminium" (http:/ / books. google. com/ ?id=td0jD4it63cC& pg=PT29). Light alloys from traditional

alloys to nanocrystals. Oxford: Elsevier/Butterworth-Heinemann. pp. 15–16. ISBN 9780750663717. .[48] Karmarsch, Carl (1864). "Fernerer Beitrag zur Geschichte des Aluminiums" (http:/ / books. google. com/ ?id=v4MtAAAAYAAJ&

pg=PA49). Polytechnisches Journal 171 (1). .[49] S Venetski (1969). ""Silver" from clay". Metallurgist 13 (7): 451. doi:10.1007/BF00741130.[50] ChemMatters October 1990 p. 14.[51] George J. Binczewski (1995). "The Point of a Monument: A History of the Aluminum Cap of the Washington Monument" (http:/ / www.

tms. org/ pubs/ journals/ JOM/ 9511/ Binczewski-9511. html). JOM 47 (11): 20–25. .[52] G. J. Binczewski (1995). "The Point of a Monument: A History of the Aluminum Cap of the Washington Monument" (http:/ / www. tms.

org/ pubs/ journals/ JOM/ 9511/ Binczewski-9511. html). JOM 47: 20. .[53] "Cowles' Aluminium Alloys" (http:/ / moa. cit. cornell. edu/ cgi-bin/ moa/ pageviewer?frames=1& coll=moa& view=50& root=/ moa/

manu/ manu0018/ & tif=00019. TIF). The Manufacturer and Builder (New York: Western and Company, via Cornell University Library) 18(1): 13. 1886. . Retrieved 2007-10-27. and McMillan, Walter George (1891). A Treatise on Electro-Metallurgy (http:/ / books. google. com/?id=DDAKAAAAIAAJ& pg=PA302). London, Philadelphia: Charles Griffin and Company, J.B. Lippincott Company, via Google Booksscan of New York Public Library copy. pp. 302–305. . Retrieved 2007-10-26. and Sackett, William Edgar, John James Scannell and MaryEleanor Watson (1917-19-18). New Jersey's First Citizens (http:/ / books. google. com/ ?id=cNgDAAAAYAAJ& pg=PA103). New Jersey:J.J. Scannell via Google Books scan of New York Public Library copy. pp. 103–105. . Retrieved 2007-10-25.

Aluminium 46

[54] US patent 400664 (http:/ / worldwide. espacenet. com/ textdoc?DB=EPODOC& IDX=US400664), Charles Martin Hall, "Process ofReducing Aluminium from its Fluoride Salts by Electrolysis", issued 1889-04-02

[55] Wallace, Donald Holmes (1977) [1937]. Market Control in the Aluminum Industry (http:/ / books. google. com/ ?id=E-acdJWbo90C&pg=PA6). Harvard University Press via Ayer Publishing via Google Books limited view. p. 6. ISBN 0-4050-9786-7. . Retrieved 2007-10-27.

[56] Aluminum prices (http:/ / www. infomine. com/ commodities/ aluminum. asp).[57] IUPAC Periodic Table of the Elements (http:/ / www. iupac. org/ reports/ periodic_table/ index. html).[58] IUPAC Web site publication search for 'aluminum' (http:/ / www. google. com/ search?q=aluminum& sitesearch=iupac. org).[59] Bremner, John Words on Words: A Dictionary for Writers and Others Who Care about Words, pp. 22–23. ISBN 0-231-04493-3.[60] "Online Etymology Dictionary" (http:/ / www. etymonline. com/ index. php?search=Alum& searchmode=none). Etymonline.com. .

Retrieved 2010-05-03.[61] "alumium", Oxford English Dictionary. Ed. J.A. Simpson and E.S.C. Weiner, second edition Oxford: Clarendon Press, 1989. OED Online

Oxford University Press. Accessed 29 October 2006. Citation is listed as "1808 SIR H. DAVY in Phil. Trans. XCVIII. 353". The ellipsis inthe quotation is as it appears in the OED citation.

[62] Davy, Humphry (1808). "Electro Chemical Researches, on the Decomposition of the Earths; with Observations on the Metals obtained fromthe alkaline Earths, and on the Amalgam procured from Ammonia" (http:/ / books. google. com/ ?id=Kg9GAAAAMAAJ& pg=RA1-PA353).Philosophical Transactions of the Royal Society of London (Royal Society of London.) 98: 353. . Retrieved 2009-12-10.

[63] Davy, Humphry (1812). Elements of Chemical Philosophy (http:/ / books. google. com/ ?id=d6Y5AAAAcAAJ& pg=PA355).ISBN 0217889476. . Retrieved 2009-12-10.

[64] "Elements of Chemical Philosophy By Sir Humphry Davy" (http:/ / books. google. com/ ?id=uGykjvn032IC& pg=PA72). Quarterly Review(John Murray) VIII: 72. 1812. ISBN 0217889476. . Retrieved 2009-12-10.

[65] Quinion, Michael (December 16, 2000). "ALUMINIUM VERSUS ALUMINUM: Why two spellings?" (http:/ / www. worldwidewords.org/ articles/ aluminium. htm). World Wide Words. ., "In the USA, the position was more complicated. Noah Webster's Dictionary of 1828has only aluminum, though the standard spelling among US chemists throughout most of the nineteenth century was aluminium; it was thepreferred version in The Century Dictionary of 1889 and is the only spelling given in the Webster Unabridged Dictionary of 1913."

[66] Meiers, Peter. "Manufacture of Aluminum" (http:/ / www. fluoride-history. de/ p-aluminum. htm). The History of Fluorine, Fluoride andFluoridation. .

[67] Banks, W.A.; Kastin, AJ (1989). "Aluminum-induced neurotoxicity: alterations in membrane function at the blood-brain barrier". NeurosciBiobehav Rev 13 (1): 47–53. doi:10.1016/S0149-7634(89)80051-X. PMID 2671833.

[68] Abreo, V.. "The Dangers of Aluminum Toxicity" (http:/ / www. bellaonline. com/ articles/ art7739. asp). . Retrieved 2009-05-05.[69] Slanina, P.; Frech, W; Ekström, LG; Lööf, L; Slorach, S; Cedergren, A (1 March 1986). "Dietary citric acid enhances absorption of

aluminum in antacids" (http:/ / www. clinchem. org/ cgi/ content/ abstract/ 32/ 3/ 539). Clinical Chemistry (American Association for ClinicalChemistry) 32 (3): 539–541. PMID 3948402. . Retrieved 2008-10-09.

[70] Van Ginkel, MF; Van Der Voet, GB; D'haese, PC; De Broe, ME; De Wolff, FA (1993). "Effect of citric acid and maltol on the accumulationof aluminum in rat brain and bone". The Journal of laboratory and clinical medicine 121 (3): 453–60. PMID 8445293.

[71] Darbre, P. D. (2006). "Metalloestrogens: an emerging class of inorganic xenoestrogens with potential to add to the oestrogenic burden of thehuman breast". Journal of Applied Toxicology 26 (3): 191–7. doi:10.1002/jat.1135. PMID 16489580.

[72] Gitelman, H. J. "Physiology of Aluminum in Man" (http:/ / books. google. com/ books?id=wRnOytsi8boC& pg=PA90), in Aluminum andHealth, CRC Press, 1988, ISBN 0824780264, p. 90

[73] Ferreira, PC; Piai Kde, A; Takayanagui, AM; Segura-Muñoz, SI (2008). "Aluminum as a risk factor for Alzheimer's disease". Revistalatino-americana de enfermagem 16 (1): 151–7. doi:10.1590/S0104-11692008000100023. PMID 18392545.

[74] Yokel RA, Hicks CL, Florence RL (2008). "Aluminum bioavailability from basic sodium aluminum phosphate, an approved food additiveemulsifying agent, incorporated in cheese". Food and chemical toxicology 46 (6): 2261–6. doi:10.1016/j.fct.2008.03.004. PMC 2449821.PMID 18436363.

[75] Exley C, Charles LM, Barr L, Martin C, Polwart A, Darbre PD (2007). "Aluminium in human breast tissue". J. Inorg. Biochem. 101 (9):1344–6. doi:10.1016/j.jinorgbio.2007.06.005. PMID 17629949.

[76] Ferreira PC, Piai Kde A, Takayanagui AM, Segura-Muñoz SI (2008). "Aluminum as a risk factor for Alzheimer's disease" (http:/ / www.scielo. br/ scielo. php?script=sci_arttext& pid=S0104-11692008000100023& lng=en& nrm=iso& tlng=en). Rev Lat Am Enfermagem 16 (1):151–7. doi:10.1590/S0104-11692008000100023. PMID 18392545. .

[77] Hawkes, Nigel (2006-04-20). "Alzheimers linked to aluminium pollution in tap water" (http:/ / www. timesonline. co. uk/ tol/ news/ uk/health/ article707311. ece). The Times (London). . Retrieved 2010-04-07.

[78] Aluminium and Alzheimer's disease (http:/ / alzheimers. org. uk/ site/ scripts/ documents_info. php?documentID=99), The Alzheimer'sSociety. Retrieved 30 January 2009.

[79] Rondeau, V.; Jacqmin-Gadda, H.; Commenges, D.; Helmer, C.; Dartigues, J.-F. (2008). "Aluminum and Silica in Drinking Water and theRisk of Alzheimer's Disease or Cognitive Decline: Findings From 15-Year Follow-up of the PAQUID Cohort". American Journal ofEpidemiology 169 (4): 489–96. doi:10.1093/aje/kwn348. PMC 2809081. PMID 19064650.

[80] Yumoto, Sakae; Kakimi, Shigeo; Ohsaki, Akihiro; Ishikawa, Akira (2009). "Demonstration of aluminum in amyloid fibers in the cores ofsenile plaques in the brains of patients with Alzheimer’s disease". Journal of Inorganic Biochemistry 103 (11): 1579–84.doi:10.1016/j.jinorgbio.2009.07.023. PMID 19744735.

Aluminium 47

[81] "Alzheimer's Disease and Aluminum" (http:/ / www. niehs. nih. gov/ external/ faq/ aluminum. htm). National Institute of EnvironmentalHealth Sciences. 2005. .

[82] Hopkin, Michael (21 April 2006). "Death of Alzheimer victim linked to aluminium pollution". news @ nature.com.doi:10.1038/news060417-10.

[83] Belmonte Pereira, Luciane; Aimed Tabaldi, Luciane; Fabbrin Gonçalves, Jamile; Jucoski, Gladis Oliveira; Pauletto, Mareni Maria; NardinWeis, Simone; Texeira Nicoloso, Fernando; Borher, Denise et al. (2006). "Effect of aluminum on δ-aminolevulinic acid dehydratase (ALA-D)and the development of cucumber (Cucumis sativus)" (http:/ / cat. inist. fr/ ?aModele=afficheN& cpsidt=17788836). Environmental andexperimental botany 57 (1–2): 106–115. .

[84] Andersson, Maud (1988). "Toxicity and tolerance of aluminium in vascular plants". Water, Air, & Soil Pollution 39 (3–4): 439–462.doi:10.1007/BF00279487.

[85] Horst, Walter J. (1995). "The role of the apoplast in aluminium toxicity and resistance of higher plants: A review". Zeitschrift fürPflanzenernährung und Bodenkunde 158 (5): 419–428. doi:10.1002/jpln.19951580503.

[86] Ma, Jian Feng; Ryan, PR; Delhaize, E (2001). "Aluminium tolerance in plants and the complexing role of organic acids". Trends in PlantScience 6 (6): 273–278. doi:10.1016/S1360-1385(01)01961-6. PMID 11378470.

[87] Turner, R.C. and Clark J.S. (1966). "Lime potential in acid clay and soil suspensions". Trans. Comm. II & IV Int. Soc. Soil Science:208–215.

[88] "corrected lime potential (formula)" (http:/ / web. archive. org/ web/ 20110706181657/ http:/ / sis. agr. gc. ca/ cansis/ glossary/corrected_lime_potential. html). Sis.agr.gc.ca. 2008-11-27. . Retrieved 2010-05-03.

[89] Turner, R.C. (1965). "A Study of the Lime Potential" (http:/ / journals. lww. com/ soilsci/ Citation/ 1965/ 07000/A_Study_of_the_Lime_Potential__5__Significance_of. 3. aspx). Research Branch, Department Of Agriculture. .

[90] Applying lime to soils reduces the Aluminum toxicity to plants. "One Hundred Harvests Research Branch Agriculture Canada 1886–1986"(http:/ / epe. lac-bac. gc. ca/ 100/ 205/ 301/ ic/ cdc/ agrican/ pubweb/ hs270060. asp). Historical series / Agriculture Canada – Série historique/ Agriculture Canada. Government of Canada. . Retrieved 2008-12-22.

[91] Magalhaes, J. V.; Garvin, DF; Wang, Y; Sorrells, ME; Klein, PE; Schaffert, RE; Li, L; Kochian, LV (2004). "Comparative Mapping of aMajor Aluminum Tolerance Gene in Sorghum and Other Species in the Poaceae". Genetics 167 (4): 1905. doi:10.1534/genetics.103.023580.PMC 1471010. PMID 15342528.

External links• Electrolytic production (http:/ / electrochem. cwru. edu/ encycl/ art-a01-al-prod. htm)• World production of primary aluminium, by country (http:/ / www. indexmundi. com/ en/ commodities/ minerals/

aluminum/ aluminum_table12. html)• Price history of aluminum, according to the IMF (http:/ / www. indexmundi. com/ commodities/

?commodity=aluminum& months=300)• History of Aluminium (from the website of the International Aluminium Institute) (http:/ / www.

world-aluminium. org/ About+ Aluminium/ Story+ of/ In+ history)• Emedicine – Aluminium (http:/ / www. emedicine. com/ med/ topic113. htm)

Gallium 48

Gallium

Gallium

Appearance

silver-white

General properties

Name, symbol, number gallium, Ga, 31

Pronunciation  /ˈɡæliəm/ gal-ee-əm

Element category post-transition metal

Group, period, block 13, 4, p

Standard atomic weight 69.723(1) g·mol−1

Electron configuration [Ar] 4s2 3d10 4p1

Electrons per shell 2, 8, 18, 3 (Image)

Physical properties

Phase solid

Density (near r.t.) 5.91 g·cm−3

Liquid density at m.p. 6.095 g·cm−3

Melting point 302.9146 K,29.7646 °C,85.5763 °F

Boiling point 2477 K,2204 °C,3999 °F

Heat of fusion 5.59 kJ·mol−1

Heat of vaporization 254 kJ·mol−1

Specific heat capacity (25 °C) 25.86 J·mol−1·K−1

Vapor pressure

P/Pa 1 10 100 1 k 10 k 100 k

at T/K 1310 1448 1620 1838 2125 2518

Atomic properties

Oxidation states 3, 2, 1(amphoteric oxide)

Electronegativity 1.81 (Pauling scale)

Gallium 49

Ionization energies(more)

1st: 578.8 kJ·mol−1

2nd: 1979.3 kJ·mol−1

3rd: 2963 kJ·mol−1

Atomic radius 135 pm

Covalent radius 122±3 pm

Van der Waals radius 187 pm

Miscellanea

Crystal structure orthorhombic

Magnetic ordering diamagnetic

Electrical resistivity (20 °C) 270 nΩ·m

Thermal conductivity (300 K) 40.6 W·m−1·K−1

Thermal expansion (25 °C) 1.2 µm·m−1·K−1

Speed of sound (thin rod) (20 °C) 2740 m/s

Young's modulus 9.8 GPa

Poisson ratio 0.47

Mohs hardness 1.5

Brinell hardness 60 MPa

CAS registry number 7440-55-3

Most stable isotopes

iso NA half-life DM DE (MeV) DP

69Ga 60.11% 69Ga is stable with 38 neutron

71Ga 39.89% 71Ga is stable with 40 neutron

Gallium (  /ˈɡæliəm/ gal-ee-əm) is a chemical element that has the symbol Ga and atomic number 31. Elementalgallium does not occur in nature, but as the gallium(III) salt in trace amounts in bauxite and zinc ores. A soft silverymetallic poor metal, elemental gallium is a brittle solid at low temperatures. As it liquefies slightly above roomtemperature, it will melt in the hand. Its melting point is used as a temperature reference point, and from itsdiscovery in 1875 to the semiconductor era, its primary uses were in high-temperature thermometric applications andin preparation of metal alloys with unusual properties of stability, or ease of melting; some being liquid at roomtemperature or below. The alloy Galinstan (68.5% Ga, 21.5% In, 10% Sn) has a melting point of about −19 °C(−2 °F).In semiconductors, the major-use compound is gallium arsenide used in microwave circuitry and infraredapplications. Gallium nitride and indium gallium nitride, minority semiconductor uses, produce blue and violetlight-emitting diodes (LEDs) and diode lasers. Semiconductor use is now almost the entire (> 95%) world market forgallium, but new uses in alloys and fuel cells continue to be discovered.Gallium is not known to be essential in biology, but because of the biological handling of gallium's primary ionic saltgallium(III) as though it were iron(III), the gallium ion localizes to and interacts with many processes in the body inwhich iron(III) is manipulated. As these processes include inflammation, which is a marker for many disease states,several gallium salts are used, or are in development, as both pharmaceuticals and radiopharmaceuticals in medicine.

Gallium 50

PropertiesElemental gallium is not found in nature, but it is easily obtained by smelting. Very pure gallium metal has a brilliantsilvery color and its solid metal fractures conchoidally like glass. Gallium metal expands by 3.1% when it solidifies,and therefore storage in either glass or metal containers is avoided, due to the possibility of container rupture withfreezing. Gallium shares the higher-density liquid state with only a few materials like silicon, germanium, bismuth,antimony and water.Gallium attacks most other metals by diffusing into their metal lattice. Gallium for example diffuses into the grainboundaries of Al/Zn alloys[1] or steel,[2] making them very brittle. Also, gallium metal easily alloys with manymetals, and was used in small quantities as a plutonium-gallium alloy in the plutonium cores of the first and thirdnuclear bombs, to help stabilize the plutonium crystal structure.[3]

The melting point of 302.9146 K (29.7646 °C, 85.5763 °F) is near room temperature. Gallium's melting point (mp)is one of the formal temperature reference points in the International Temperature Scale of 1990 (ITS-90) establishedby BIPM.[4] [5] [6] The triple point of gallium of 302.9166 K (29.7666 °C, 85.5799 °F), is being used by NIST inpreference to gallium's melting point.[7]

Gallium is a metal that will melt in one's hand. This metal has a strong tendency to supercool below its meltingpoint/freezing point. Seeding with a crystal helps to initiate freezing. Gallium is one of the metals (with caesium,rubidium, francium and mercury) which are liquid at or near normal room temperature, and can therefore be used inmetal-in-glass high-temperature thermometers. It is also notable for having one of the largest liquid ranges for ametal, and (unlike mercury) for having a low vapor pressure at high temperatures. Unlike mercury, liquid galliummetal wets glass and skin, making it mechanically more difficult to handle (even though it is substantially less toxicand requires far fewer precautions). For this reason as well as the metal contamination problem andfreezing-expansion problems noted above, samples of gallium metal are usually supplied in polyethylene packetswithin other containers.

Crystallization of gallium from the melt

Gallium does not crystallize in any of the simple crystal structures. Thestable phase under normal conditions is orthorhombic with 8 atoms inthe conventional unit cell. Each atom has only one nearest neighbor (ata distance of 244 pm) and six other neighbors within additional 39 pm.Many stable and metastable phases are found as function oftemperature and pressure.

The bonding between the nearest neighbors is found to be of covalentcharacter, hence Ga2 dimers are seen as the fundamental buildingblocks of the crystal. This explains the drop of the melting pointcompared to its neighbour elements aluminium and indium. Thecompound with arsenic, gallium arsenide is a semiconductor

commonly used in light-emitting diodes.

High-purity gallium is dissolved slowly by mineral acids.

Gallium 51

HistoryIn 1871, existence of gallium was first predicted by Russian chemist Dmitri Mendeleev, who named it"eka-aluminium" on the basis of its position in his periodic table. He also predicted several properties of the element,which correspond close to real gallium properties, such as density, melting point, oxide character and bonding inchloride.[8]

Gallium was discovered spectroscopically by Paul Emile Lecoq de Boisbaudran in 1875 by its characteristicspectrum (two violet lines) in an examination of a sphalerite sample.[9] Later that year, Lecoq obtained the free metalby electrolysis of its hydroxide in potassium hydroxide solution. He named the element "gallia", from Latin Galliameaning gaul, after his native land of France. It was later claimed that, in one of those multilingual puns so belovedof men of science in the 19th century, he had also named gallium after himself, as his name, "Le coq", is the Frenchfor "the rooster", and the Latin for "rooster" is "gallus"; however, in an 1877 article Lecoq denied thissupposition.[10] (Cf. the naming of the J/ψ meson.)

OccurrenceGallium does not exist in free form in nature, and the few high-gallium minerals such as gallite (CuGaS2) are toorare to serve as a primary source of the element or its compounds. Its abundance in the Earth's crust is approximately16.9 ppm.[11] Gallium is found and extracted as a trace component in bauxite and to a small extent from sphalerite.The amount extracted from coal, diaspore and germanite in which gallium is also present is negligible. The UnitedStates Geological Survey (USGS) estimates gallium reserves to exceed 1 million tonnes, based on 50 ppm by weightconcentration in known reserves of bauxite and zinc ores.[12] [13] Some flue dusts from burning coal have beenshown to contain small quantities of gallium, typically less than 1% by weight.[14] [15] [16] [17]

ProductionThe only two economic sources for gallium are as byproduct of aluminium and zinc production, while the sphaleritefor zinc production is the minor source. Most gallium is extracted from the crude aluminium hydroxide solution ofthe Bayer process for producing alumina and aluminium. A mercury cell electrolysis and hydrolysis of the amalgamwith sodium hydroxide leads to sodium gallate. Electrolysis then gives gallium metal. For semiconductor use, furtherpurification is carried out using zone melting, or else single crystal extraction from a melt (Czochralski process).Purities of 99.9999% are routinely achieved and commercially widely available.[18] An exact number for the worldwide production is not available, but it is estimated that in 2007 the production of gallium was 184 tonnes with lessthan 100 tonnes from mining and the rest from scrap recycling.[12]

Applications

Semiconductors

Gallium 52

Gallium based blue LEDs

The semiconductor applications are the main reason for the low-costcommercial availability of the extremely high-purity (99.9999+%)metal.Gallium arsenide (GaAs) and gallium nitride (GaN) used in electroniccomponents represented about 98% of the gallium consumption in theUnited States in 2007. About 66% of semiconductor gallium is used inthe U.S. in integrated circuits (mostly gallium arsenide), such as themanufacture of ultra-high speed logic chips and MESFETs forlow-noise microwave preamplifiers in cell phones. About 20% is usedin optoelectronics.[12] World wide gallium arsenide makes up 95% ofthe annual global gallium consumption.[18]

Gallium arsenide is used in optoelectronics in a variety of infrared applications. Aluminium gallium arsenide(AlGaAs) is used in high-powered infrared laser diodes. As a component of the semiconductors indium galliumnitride and gallium nitride, gallium is used to produce blue and violet optoelectronic devices, mostly laser diodes andlight-emitting diodes. For example, gallium nitride 405 nm diode lasers are used as a violet light source forhigher-density compact disc data storage, in the Blu-ray Disc standard.[19]

Gallium is used as a dopant for the production of solid-state devices such as transistors. However, worldwide theactual quantity used for this purpose is minute, since dopant levels are usually of the order of a few parts per million.Multijunction photovoltaic cells, developed for satellite power applications, are made by molecular beam epitaxy ormetalorganic vapour phase epitaxy of thin films of gallium arsenide, indium gallium phosphide or indium galliumarsenide.The Mars Exploration Rovers and several satellites use triple junction gallium arsenide on germaniumcells.[20] Gallium is also a component in photovoltaic compounds (such as copper indium gallium selenium sulfideor Cu(In,Ga)(Se,S)2) for use in solar panels as a cost-efficient alternative to crystalline silicon.[21]

Wetting and alloy improvement• Because gallium wets glass or porcelain, gallium can be used to create brilliant mirrors. When the wetting action

of gallium-alloys is not desired (as in Galinstan glass thermometers), the glass must be protected with atransparent layer of gallium(III) oxide.[22]

• Gallium readily alloys with most metals, and has been used as a component in low-melting alloys. The plutoniumused in nuclear weapon pits is machined by alloying with gallium to stabilize its δ phase.[23]

• Gallium added in quantities up to 2% in common solders can aid wetting and flow characteristics.

Galinstan and other liquid alloysA nearly eutectic alloy of gallium, indium, and tin is a room temperature liquid which is widely available in medicalthermometers, replacing problematic mercury. This alloy, with the trade-name Galinstan (with the "-stan" referringto the tin), has a low freezing point of −19 °C (−2.2°F).[24] It has been suggested that this family of alloys could alsobe used to cool computer chips in place of water.[25] Much research is being devoted to gallium alloys as substitutesfor mercury dental amalgams, but these compounds have yet to see wide acceptance.

Energy storageAluminium is reactive enough to reduce water to hydrogen, being oxidized to aluminium oxide. However, the aluminium oxide forms a protective coat which prevents further reaction. Galinstan has been applied to activate aluminium (removing the oxide coat), so that aluminium can react with water, generating hydrogen and steam in a reaction being considered as a helpful step in a hydrogen economy.[26] A number of other gallium-aluminium alloys are also usable for the purpose of essentially acting as chemical energy store to generate hydrogen from water,

Gallium 53

on-site.After reaction with water the resultant aluminium oxide and gallium mixture must be reformed back into electrodeswith energy input.[26] [27] The thermodynamic efficiency of the aluminium smelting process is estimated as 50%.[28]

Therefore, at most only half the energy that goes into smelting the aluminium could be recovered by a hydrogen fuelcell.

Biomedical applications

Gallium(III) salts

• Gallium nitrate (brand name Ganite) has been used as an intravenous pharmaceutical to treat hypercalcemiaassociated with tumor metastasis to bones. Gallium is thought to interfere with osteoclast function. It may beeffective when other treatments for maligancy-associated hypercalcemia are not.[29]

• Gallium maltolate, an orally-aborbable form of gallium(III) ion, is in clinical and preclinical trials as a potentialtreatment for a number of types of cancer, infectious disease, and inflammatory disease.[30]

• Research is being conducted to determine whether gallium ion can be used to fight bacterial infections in peoplewith cystic fibrosis. Gallium is similar in size to iron, an essential nutrient for respiration. When gallium ions aremistakenly picked up by bacteria such as Pseudomonas, the bacteria's ability to respire is interfered with and thebacteria die. The mechanism behind this is that iron is redox active, which allows for the transfer of electronsduring respiration, but gallium is redox inactive.[31] [32]

• In several studies, a complex amine-phenol Ga(III) compound MR045 was found to be selectively toxic toparasites that have developed resistance to chloroquine, a common drug against malaria. Both the Ga(III)complex and chloroquine act by inhibiting crystallization of hemozoin, a disposal product formed from thedigestion of blood by the parasites.[33] [34]

Radiogallium salts

Gallium-67 salts such as gallium citrate and gallium nitrate are used as radiopharmaceutical agents in a nuclearmedicine imaging procedure commonly referred to as a gallium scan. The form or salt of gallium is not important,since it is the free dissolved gallium ion Ga3+ which is the active radiotracer. For these applications, the radioactiveisotope 67Ga is used. The body handles Ga3+ in many ways as though it were iron, and thus it is bound (andconcentrates) in areas of inflammation, such as infection, and also areas of rapid cell division. This allows such sitesto be imaged by nuclear scan techniques. This use has largely been replaced by fluorodeoxyglucose (FDG) forpositron emission tomography, "PET" scan and indium-111 labelled leukocyte scans. However, the localization ofgallium in the body has some properties which make it unique in some circumstances from competing modalitiesusing other radioisotopes.Gallium-68, a positron emitter with a half life of 68 min., is now used as a diagnostic radionuclide in PET-CT whenlinked to pharmaceutical preparations such as DOTATOC, a somatostatin analogue used for neuroendocrine tumorsinvestigation, and DOTA-TATE, a newer one, used for neuroendocrine metastasis and lung neuroendocrine cancer,such as certain types of microcytoma. Galium-68's preparation as a pharmaceutical is chemical and the radionuclideis extracted by elution from germanium-68, a synthetic radioisotope of germanium, in gallium-68 generators.

Gallium 54

Other uses• Magnesium gallate containing impurities (such as Mn2+), is beginning to be used in ultraviolet-activated phosphor

powder.• Neutrino detection. Possibly the largest amount of pure gallium ever collected in a single spot is the

Gallium-Germanium Neutrino Telescope used by the SAGE experiment at the Baksan Neutrino Observatory inRussia. This detector contains 55–57 tonnes of liquid gallium.[35] Another experiment was the GALLEX neutrinodetector operated in the early 1990s in an Italian mountain tunnel. The detector contained 12.2 tons of wateredgallium-71. Solar neutrinos caused a few atoms of Ga-71 to become radioactive Ge-71, which were detected. Thesolar neutrino flux deduced was found to have a deficit of 40% from theory. This was not explained until bettersolar neutrino detectors and theories were constructed (see SNO).[36]

• As a liquid metal ion source for a focused ion beam.• As alloying element in the magnetic shape memory alloy Ni-Mn-Ga.• In a classic prank by scientists, who fashion gallium spoons and serve tea to unsuspecting guests. The spoons melt

in the hot tea.[37]

• As an additive in glide wax for skiis, and other low friction surface materials. US 5069803 [38], Sugimura,Kentaro; Shoji Hasimoto & Takayuki Ono, "Use of a synthetic resin composition containing gallium particles inthe glide surfacing material of skis and other applications", issued 1995

ChemistryGallium is found primarily in the +3 oxidation state. The +1 oxidation is also attested in some compounds, althoughthey tend to disproportionate into elemental gallium and gallium(III) compounds. What are sometimes referred to asgallium(II) compounds are actually mixed-oxidation state compounds containing both gallium(I) and gallium(III).[39]

Chalcogen compoundsAt room temperature, gallium metal is unreactive towards air and water due to the formation of a passive, protectiveoxide layer. At higher temperatures, however, it reacts with oxygen in the air to form gallium(III) oxide, Ga2O3.[39]

Reducing Ga2O3 with elemental gallium in vacuum at 500 °C to 700 °C yields the dark brown gallium(I) oxide,Ga2O.[40] :285 Ga2O is a very strong reducing agent, capable of reducing H2SO4 to H2S.[40] :207 It disproportionatesat 800 °C back to gallium and Ga2O3.[41]

Gallium sulfide, Ga2S3, has 3 possible crystal modifications.[41] :104 It can be made by the reaction of gallium withhydrogen sulfide (H2S) at 950 °C.[40] :162 Alternatively, Ga(OH)3 can also be used at 747 °C:[42]

2 Ga(OH)3 + 3 H2S → Ga2S3 + 6 H2OReacting a mixture of alkali metal carbonates and Ga2O3 with H2S leads to the formation of thiogallates containingthe [Ga2S4]2− anion. Strong acids decompose these salts, releasing H2S in the process.[41] :104–105 The mercury salt,HgGa2S4, can be used as a phosphor.[43]

Gallium also forms sulfides in lower oxidation states, such as gallium(II) sulfide and the green gallium(I) sulfide, thelatter of which is produced from the former by heating to 1000 °C under a stream of nitrogen.[41] :94

The other binary chalcogenides, Ga2Se3 and Ga2Te3, have zincblende structure. They are all semiconductors, but areeasily hydrolysed, limiting their usefulness.[41] :104

Gallium 55

Aqueous chemistryStrong acids dissolve gallium, forming gallium(III) salts such as Ga2(SO4)3 and Ga(NO3)3. Aqueous solutions ofgallium(III) salts contain the hydrated gallium ion, [Ga(H2O)6]3+.[44] :1033 Gallium(III) hydroxide, Ga(OH)3, may beprecipitated from gallium(III) solutions by adding ammonia. Dehydrating Ga(OH)3 at 100 °C produces galliumoxide hydroxide, GaO(OH).[40] :140–141

Alkaline hydroxide solutions dissolve gallium, forming gallate salts containing the Ga(OH) anion.[39] [44] :1033[45]

Gallium hydroxide, which is amphoteric, also dissolves in alkali to form gallate salts.[40] :141 Although earlier worksuggested Ga(OH) as another possible gallate anion,[46] this species was not found in later work.[45]

Pnictogen compoundsGallium reacts with ammonia at 1050 °C to form gallium nitride, GaN. Gallium also forms binary compounds withphosphorus, arsenic, and antimony: gallium phosphide (GaP), gallium arsenide (GaAs), and gallium antimonide(GaSb). These compounds have the same structure as ZnS, and have important semiconducting properties.[44] :1034

GaP, GaAs, and GaSb can be synthesized by the direct reaction of gallium with elemental phosphorus, arsenic, orantimony.[41] :99 They exhibit higher electrical conductivity than GaN.[41] :101 GaP can also be synthesized by thereaction of Ga2O with phosphorus at low temperatures.[47]

Gallium also forms ternary nitrides; for example:[41] :99

Li3Ga + N2 → Li3GaN2Similar compounds with phosphorus and antimony also exist: Li3GaP2 and Li3GaAs2. These compounds are easilyhydrolyzed by dilute acids and water.[41] :101

HalidesGallium(III) oxide reacts with fluorinating agents such as HF or F2 to form gallium(III) fluoride, GaF3. It is an ioniccompound strongly insoluble in water. However, it does dissolve in hydrofluoric acid, in which it forms an adductwith water, GaF3·3H2O. Attempting to dehydrate this adduct instead forms GaF2OH·nH2O. The adduct reacts withammonia to form GaF3·3NH3, which can then be heated to form anhydrous GaF3.[40] :128–129

Gallium trichloride is formed by the reaction of gallium metal with chlorine gas.[39] Unlike the trifluoride,gallium(III) chloride exists as dimeric molecules, Ga2Cl6, with a melting point of 78 °C. This is also the case for thebromide and iodide, Ga2Br6 and Ga2I6.[40] :133

Like the other group 13 trihalides, gallium(III) halides are Lewis acids, reacting as halide acceptors with alkali metalhalides to form salts containing GaX anions, where X is a halogen. They also react with alkyl halides to formcarbocations and GaX.[40] :136–137

When heated to a high temperature, gallium(III) halides react with elemental gallium to form the respectivegallium(I) halides. For example, GaCl3 reacts with Ga to form GaCl:

2 Ga + GaCl3 3 GaCl (g)At lower temperatures, the equilibrium shifts toward the left and GaCl disproportionates back to elemental galliumand GaCl3. GaCl can also be made by the reaction of Ga with HCl at 950 °C; it can then be condensed as redsolid.[44] :1036

Gallium(I) compounds can be stabilized by forming adducts with Lewis acids. For example:GaCl + AlCl3 → Ga+[AlCl4]−

The so-called "gallium(II) halides", GaX2, are actually adducts of gallium(I) halides with the respective gallium(III)halides, having the structure Ga+[GaX4]−. For example:[39] [44] :1036[48]

GaCl + GaCl3 → Ga+[GaCl4]−

Gallium 56

Hydrogen compoundsLike aluminium, gallium also forms a hydride, GaH3, known as gallane, which may be obtained by the reaction oflithium gallanate (LiGaH4) with gallium(III) chloride at −30 °C:[44] :1031

3 LiGaH4 + GaCl3 → 3 LiCl + 4 GaH3In the presence of dimethyl ether as solvent, GaH3 polymerizes to (GaH3)n. If no solvent is used, the dimer Ga2H6(digallane) is formed as a gas. Its structure is similar to diborane, having two hydrogen atoms bridging the twogallium centers,[44] :1031 unlike α-AlH3 in which aluminium has a coordination number of 6.[44] :1008

Gallane is unstable above −10 °C, decomposing to elemental gallium and hydrogen.[49]

PrecautionsWhile not considered toxic, the data about gallium are inconclusive. Some sources suggest that it may causedermatitis from prolonged exposure; other tests have not caused a positive reaction. Like most metals, finely dividedgallium loses its luster and powdered gallium appears gray. Thus, when gallium is handled with bare hands, theextremely fine dispersion of liquid gallium droplets, which results from wetting skin with the metal, may appear as agray skin stain.

References[1] W. L. Tsai, Y. Hwu, C. H. Chen, L. W. Chang, J. H. Je, H. M. Lin, G. Margaritondo (2003). "Grain boundary imaging, gallium diffusion and

the fracture behavior of Al–Zn Alloy – An in situ study". Nuclear Instruments and Methods in Physics Research Section B 199: 457.Bibcode 2003NIMPB.199..457T. doi:10.1016/S0168-583X(02)01533-1.

[2] Vigilante, G. N., Trolano, E., Mossey, C. (June 1999). "Liquid Metal Embrittlement of ASTM A723 Gun Steel by Indium and Gallium"(http:/ / stinet. dtic. mil/ oai/ oai?& verb=getRecord& metadataPrefix=html& identifier=ADA365497). Defense Technical Information Center.. Retrieved 2009-07-07.

[3] Sublette,Cary (2001-09-09). "Section 6.2.2.1" (http:/ / nuclearweaponarchive. org/ Nwfaq/ Nfaq6. html#nfaq6. 2). Nuclear Weapons FAQ. .Retrieved 2008-01-24.

[4] Preston–Thomas, H. (1990). "The International Temperature Scale of 1990 (ITS-90)" (http:/ / www. bipm. org/ utils/ common/ pdf/ its-90/ITS-90_metrologia. pdf). Metrologia 27: 3–10. Bibcode 1990Metro..27....3P. doi:10.1088/0026-1394/27/1/002. .

[5] "ITS-90 documents at Bureau International de Poids et Mesures" (http:/ / www. bipm. org/ en/ publications/ its-90. html). .[6] Magnum, B.W.; Furukawa, G.T. (August 1990). "Guidelines for Realizing the International Temperature Scale of 1990 (ITS-90)" (http:/ /

www. cstl. nist. gov/ div836/ 836. 05/ papers/ magnum90ITS90guide. pdf). National Institute of Standards and Technology. NIST TN 1265. .[7] Strouse, Gregory F. (1999). "NIST realization of the gallium triple point" (http:/ / www. cstl. nist. gov/ div836/ 836. 05/ papers/

Strouse99GaTP. pdf). National Institute of Standards and Technology. . Retrieved 2009-07-07.[8] Ball, Philip (2002). The Ingredients: A Guided Tour of the Elements. Oxford University Press. p. 105. ISBN 0-19-284100-9.[9] de Boisbaudran, Lecoq. "Caractères chimiques et spectroscopiques d'un nouveau métal, le gallium, découvert dans une blende de la mine de

Pierrefitte, vallée d'Argelès (Pyrénées)" (http:/ / gallica. bnf. fr/ ark:/ 12148/ bpt6k3038w/ f490. table). Comptes rendus 81: 493. . Retrieved2008-09-23.

[10] Weeks, Mary Elvira (1932). "The discovery of the elements. XIII. Some elements predicted by Mendeleeff". Journal of Chemical Education9 (9): 1605–1619. Bibcode 1932JChEd...9.1605W. doi:10.1021/ed009p1605.

[11] Burton, J. D.; Culkin, F.; Riley, J. P. (2007). "The abundances of gallium and germanium in terrestrial materials". Geochimica etCosmochimica Acta 16: 151. Bibcode 1959GeCoA..16..151B. doi:10.1016/0016-7037(59)90052-3.

[12] Kramer, Deborah A.. "Mineral Commodity Summary 2006: Gallium" (http:/ / minerals. usgs. gov/ minerals/ pubs/ commodity/ gallium/mcs-2008-galli. pdf). United States Geological Survey. . Retrieved 2008-11-20.

[13] Kramer, Deborah A.. "Mineral Yearbook 2006: Gallium" (http:/ / minerals. usgs. gov/ minerals/ pubs/ commodity/ gallium/myb1-2006-galli. pdf). United States Geological Survey. . Retrieved 2008-11-20.

[14] Shan Xiao-quan, Wang Wen and Wen Bei (1992). "Determination of gallium in coal and coal fly ash by electrothermal atomic absorptionspectrometry using slurry sampling and nickel chemical modification". Journal of Analytical Atomic Spectrometry 7 (5): 761.doi:10.1039/JA9920700761.

[15] "Gallium in West Virginia Coals" (http:/ / www. wvgs. wvnet. edu/ www/ datastat/ te/ GaHome. htm). West Virginia Geological andEconomic Survey. 2002-03-02. .

[16] O. Font, X. Querol, R. Juan, R. Casado, C. R. Ruiz, A. Lopez-Soler, P. Coca and F. G. Pena (2007). "Recovery of gallium and vanadiumfrom gasification fly ash". Journal of Hazardous Materials 139 (3): 413–23. doi:10.1016/j.jhazmat.2006.02.041. PMID 16600480.

Gallium 57

[17] A. J. W. Headlee and Richard G. Hunter (1953). "Elements in Coal Ash and Their Industrial Significance". Industrial and EngineeringChemistry 45 (3): 548. doi:10.1021/ie50519a028.

[18] Moskalyk, R. R. (2003). "Gallium: the backbone of the electronics industry". Minerals Engineering 16 (10): 921.doi:10.1016/j.mineng.2003.08.003.

[19] Sony says Blu-ray Disc 405 nm violet laser diodes use GaN (http:/ / www. sony. net/ Products/ SC-HP/ laserdiodewld/ tec/ index03. html)[20] Crisp, D.; Pathare, A.; Ewell, R. C. (2004). "The performance of gallium arsenide/germanium solar cells at the Martian surface". Progress in

Photovoltaics Research and Applications 54 (2): 83. doi:10.1016/S0094-5765(02)00287-4.[21] Alberts, V.; Titus J.; Birkmire R. W. (2003). "Material and device properties of single-phase Cu(In,Ga)(Se,S)2 alloys prepared by

selenization/sulfurization of metallic alloys". Thin Solid Films 451–452: 207. Bibcode 2004TSF...451..207A. doi:10.1016/j.tsf.2003.10.092.[22] United States. Office of Naval Research. Committee on the Basic Properties of Liquid Metals,U.S. Atomic Energy Commission (1954).

Liquid-metals handbook (http:/ / books. google. com/ ?id=2EZSAAAAMAAJ& cd=2& dq=with+ the+ oxide+ to+ prevent+ wetting+ of+ the+glass+ by+ the+ gallium+ alloy& q=+ prevent+ wetting+ of+ the+ glass+ #search_anchor). U.S. Govt. Print. Off.. p. 128. .

[23] Besmann, Theodore M. (2005). "Thermochemical Behavior of Gallium in Weapons-Material-Derived Mixed-Oxide Light Water Reactor(LWR) Fuel". Journal of the American Ceramic Society 81 (12): 3071. doi:10.1111/j.1151-2916.1998.tb02740.x.

[24] Surmann, P; Zeyat, H (Nov 2005). "Voltammetric analysis using a self-renewable non-mercury electrode". Analytical and bioanalyticalchemistry 383 (6): 1009–13. doi:10.1007/s00216-005-0069-7. ISSN 1618-2642. PMID 16228199.

[25] Knight, Will (2005-05-05). "Hot chips chilled with liquid metal" (http:/ / www. newscientist. com/ article. ns?id=dn7348). . Retrieved2008-11-20.

[26] "Purdue Energy Center symposium to pave the road to a hydrogen economy" (http:/ / www. purdue. edu/ uns/ x/ 2007a/070410Gorehydrogen. html) (Press release). Purdue University. 2007-04-10. .

[27] "New process generates hydrogen from aluminum alloy to run engines, fuel cells" (http:/ / www. physorg. com/ news98556080. html).PhysOrg.com. 2007-05-16. .

[28] Das, Subodh K.; Long, W. Jerry; Hayden, H. Wayne; Green, John A. S.; Hunt, Warren H. (2004). "Energy implications of the changingworld of aluminum metal supply". JOM 56 (8): 14. Bibcode 2004JOM....56h..14D. doi:10.1007/s11837-004-0175-6.

[29] "gallium nitrate" (http:/ / www. cancer. org/ docroot/ CDG/ content/ CDG_gallium_nitrate. asp). . Retrieved 2009-07-07.[30] L. R. Bernstein, T. Tanner, C. Godfrey, B. Noll (2000). "Chemistry and Pharmacokinetics of Gallium Maltolate, a Compound With High

Oral Gallium Bioavailability". Metal Based Drugs 7 (1): 33–47. doi:10.1155/MBD.2000.33. PMC 2365198. PMID 18475921.[31] "A Trojan-horse strategy selected to fight bacteria" (http:/ / www. infoniac. com/ health-fitness/ trojan-gallium. html). INFOniac.com.

2007-03-16. . Retrieved 2008-11-20.[32] Smith, Michael (2007-03-16). "Gallium May Have Antibiotic-Like Properties" (http:/ / www. medpagetoday. com/ InfectiousDisease/

GeneralInfectiousDisease/ tb/ 5266). MedPage Today. . Retrieved 2008-11-20.[33] Goldberg DE, Sharma V, Oksman A, Gluzman IY, Wellems TE, Piwnica-Worms D (1997). "Probing the chloroquine resistance locus of

Plasmodium falciparum with a novel class of multidentate metal(III) coordination complexes". J Biol Chem. 272 (10): 6567–72.PMID 9045684.

[34] Biot, Christophe; Dive, Daniel (2010). "Bioorganometallic Chemistry and Malaria". Medicinal Organometallic Chemistry. Topics inOrganometallic Chemistry. 32. pp. 155. doi:10.1007/978-3-642-13185-1_7. ISBN 978-3-642-13184-4.

[35] "Russian American Gallium Experiment" (http:/ / ewi. npl. washington. edu/ sage/ ). 2001-10-19. . Retrieved 2009-06-24.[36] "Neutrino Detectors Experiments: GALLEX" (http:/ / wwwlapp. in2p3. fr/ neutrinos/ anexp. html#gallex). 1999-06-26. . Retrieved

2008-11-20.[37] Sam Kean (2010). The Disappearing Spoon: And Other True Tales of Madness, Love, and the History of the World from the Periodic Table

of the Elements (http:/ / samkean. com/ disappearing-spoon). Boston: Little, Brown and Company. ISBN 0-316-05164-0. .[38] http:/ / worldwide. espacenet. com/ textdoc?DB=EPODOC& IDX=US5069803[39] Mary Eagleson, ed (1994). Concise encyclopedia chemistry. Walter de Gruyter. p. 438. ISBN 3110114518.[40] Anthony John Downs (1993). Chemistry of aluminium, gallium, indium, and thallium. Springer. ISBN 075140103X.[41] N. N. Greenwood (1962). Harry Julius Emeléus, Alan G. Sharpe. ed. Advances in inorganic chemistry and radiochemistry, Volume 5.

Academic Press. pp. 94–95. ISBN 0120236052.[42] Otfried Madelung (2004). Semiconductors: data handbook (3rd ed.). Birkhäuser. pp. 276–277. ISBN 3540404880.[43] L. Krausbauer; R. Nitsche; P. Wild (1965). "Mercury gallium sulfide, HgGa2S4, a new phosphor". Physica 31 (1): 113–121.

Bibcode 1965Phy....31..113K. doi:10.1016/0031-8914(65)90110-2.[44] Egon Wiberg; Nils Wiberg; Arnold Frederick Holleman (2001). Inorganic chemistry. Academic Press. ISBN 0123526515.[45] Pál Sipos; Tünde Megyes; Ottó Berkesi (2008). "The Structure of Gallium in Strongly Alkaline, Highly Concentrated Gallate Solutions—a

Raman and 71Ga-NMR Spectroscopic Study". J Solution Chem (Springer Netherlands) 37 (10): 1411–1418. doi:10.1007/s10953-008-9314-y.[46] N. A. Hampson (1971). Harold Reginald Thirsk. ed. Electrochemistry—Volume 3: Specialist periodical report (http:/ / books. google. com/

?id=vN0Y7KMGqNcC& printsec=frontcover& q). Great Britain: Royal Society of Chemistry. p. 71. ISBN 0851860273. .[47] Michelle Davidson (2006). Inorganic Chemistry. Lotus Press. p. 90. ISBN 8189093398.[48] Amit Arora (2005). Text Book Of Inorganic Chemistry. Discovery Publishing House. pp. 389–399. ISBN 818356013X.[49] Anthony J. Downs; Colin R. Pulham (1994). A. G. Sykes. ed. Advances in Inorganic Chemistry, Volume 41. Academic Press. pp. 198–199.

ISBN 0120236419.

Gallium 58

External links• Material safety data sheet at acialloys.com (http:/ / www. acialloys. com/ msds/ ga. html)• High-resolution photographs of molten gallium, gallium crystals and gallium ingots under Creative Commons

licence (http:/ / france-gallium. com/ photos-gallium. php)• www.lenntech.com – textbook information regarding gallium (http:/ / www. lenntech. com/

Periodic-chart-elements/ Ga-en. htm)• Environmental effects of gallium (http:/ / minerals. usgs. gov/ minerals/ pubs/ commodity/ gallium/ index. html)• Price development of gallium 1959–1998 (http:/ / minerals. usgs. gov/ minerals/ pubs/ commodity/ gallium/

460798. pdf)• Technology produces hydrogen by adding water to an alloy of aluminum and gallium (http:/ / www. physorg.

com/ news107446364. html)

Indium 59

Indium

Indium

Appearance

silvery lustrous gray

General properties

Name, symbol, number indium, In, 49

Pronunciation /ˈɪndiəm/ in-dee-əm

Element category post-transition metal

Group, period, block 13, 5, p

Standard atomic weight 114.818 g·mol−1

Electron configuration [Kr] 4d10 5s2 5p1

Electrons per shell 2, 8, 18, 18, 3 (Image)

Physical properties

Phase solid

Density (near r.t.) 7.31 g·cm−3

Liquid density at m.p. 7.02 g·cm−3

Melting point 429.7485 K,156.5985 °C,313.8773 °F

Boiling point 2345 K,2072 °C,3762 °F

Heat of fusion 3.281 kJ·mol−1

Heat of vaporization 231.8 kJ·mol−1

Specific heat capacity (25 °C) 26.74 J·mol−1·K−1

Vapor pressure

P/Pa 1 10 100 1 k 10 k 100 k

at T/K 1196 1325 1485 1690 1962 2340

Atomic properties

Oxidation states 3, 2, 1 (amphoteric oxide)

Electronegativity 1.78 (Pauling scale)

Indium 60

Ionization energies 1st: 558.3 kJ·mol−1

2nd: 1820.7 kJ·mol−1

3rd: 2704 kJ·mol−1

Atomic radius 167 pm

Covalent radius 142±5 pm

Van der Waals radius 193 pm

Miscellanea

Crystal structure tetragonal

Magnetic ordering diamagnetic[1]

Electrical resistivity (20 °C) 83.7 nΩ·m

Thermal conductivity (300 K) 81.8 W·m−1·K−1

Thermal expansion (25 °C) 32.1 µm·m−1·K−1

Speed of sound (thin rod) (20 °C) 1215 m/s

Young's modulus 11 GPa

Mohs hardness 1.2

Brinell hardness 8.83 MPa

CAS registry number 7440-74-6

Most stable isotopes

iso NA half-life DM DE (MeV) DP

113In 4.3% 113In is stable with 64 neutron

115In 95.7% 4.41×1014 y β− 0.495 115Sn

Indium (  /ˈɪndiəm/ in-dee-əm) is a chemical element with the symbol In and atomic number 49. This rare, verysoft, malleable and easily fusible post-transition metal is chemically similar to gallium and thallium, and shows theintermediate properties between these two. Indium was discovered in 1863 and named for the indigo blue line in itsspectrum that was the first indication of its existence in zinc ores, as a new and unknown element. The metal wasfirst isolated in the following year. Zinc ores continue to be the primary source of indium, where it is found incompound form. Very rarely the element can be found as grains of native (free) metal, but these are not ofcommercial importance.Indium's current primary application is to form transparent electrodes from indium tin oxide in liquid crystal displaysand touchscreens, and this use largely determines its global mining production. It is widely used in thin-films to formlubricated layers (during World War II it was widely used to coat bearings in high-performance aircraft). It is alsoused for making particularly low melting point alloys, and is a component in some lead-free solders.Indium is not known to be used by any organism. In a similar way to aluminium salts, indium(III) ions can be toxicto the kidney when given by injection, but oral indium compounds do not have the chronic toxicity of salts of heavymetals, probably due to poor absorption in basic conditions. Radioactive indium-111 (in very small amounts on achemical basis) is used in nuclear medicine tests, as a radiotracer to follow the movement of labeled proteins andwhite blood cells in the body.

Indium 61

Characteristics

Physical

Indium wetting the glass surface of a test tube

Indium is a very soft, silvery-white, relatively rare true metal with abright luster. When it is bent, indium emits a high-pitched "cry".[2]

Like gallium, indium is able to wet glass. Indium has a low meltingpoint, compared to those of most other metals, 156.60 °C (313.88 °F);it is higher than that of its lighter homologue, gallium, but lower thanthat of the heavier homologue, thallium.[3] Its boiling point is,however, moderate, being 2072 °C (3762 °F), which is higher than thatof thallium, but lower than that of gallium, showing opposition tomelting points trend. The density of indium, 7.31 g·cm−3, is also higherthan that of gallium, but lower than that of thallium.[3]

Indium atom has 49 electrons, having electronic configuration [Kr]4d105s25p1. In its compounds, indium most oftenloses its three outermost electrons, becoming indium(III) ions, In3+, but in some cases the pair of 5s-electrons canstay within the atom, indium thus oxidized only to indium(I), In+. This happens due to inert pair effect, which occursbecause of stabilization of 5s-orbital due to relativistic effects, which are stronger closer to the bottom of the periodictable. Its heavier homologue, thallium, shows an even stronger effect, making oxidation to thallium(I) more likelythan to thallium(III), making +1 the more likely oxidation state.[4]

A number of standard electrode potentials, depending on the reaction under study,[5] is reported for indium:

−0.40 In2+ + e− ↔ In+

−0.49 In3+ + e− ↔ In2+

−0.443 In3+ + 2 e− ↔ In+

−0.3382 In3+ + 3 e− ↔ In

−0.14 In+ + e− ↔ In

ChemicalIndium is a post-transition metal and chemically, is the intermediate element between its group 13 neighbors galliumand thallium. It shows two main oxidation states, which are +1 and +3, with latter being more stable, where as theonly common oxidation state of gallium is +3 and thallium shows +1 more likely than +3, with thallium(III) being amoderately strong oxidizing agent, while indium(III) is stable and indium(I) is a powerful reducing agent.[6]

Indium does not react with water, but it is oxidized by stronger oxidizing agents, such as halogens or oxalic acid, togive indium(III) compounds. It does not react with boron, silicon or carbon, and the corresponding boride, silicide orcarbide are not known. Similarly, reaction between indium and hydrogen has not been observed, but both indium(I)and indium(III) hydrides are known.[7]

Indium(III) oxide is formed at hot temperatures during reaction between indium and oxygen, with blue flame. It isamphoteric, i. e. it can react with both acids and bases. Its reaction with water results in insoluble indium(III)hydroxide, which is also amphoteric, reacting with alkalies to give indates(III) and with acids to give indium(III)salts:

In(OH)3 + 2 NaOH → 2 Na[InO2] + H2OIn(OH)3 + 3 HCl → InCl3 + 3 H2O

Indium 62

The hydrolysis of sodium indate(III) gives weak indic acid, HInO2. Out of common indium(III) salts, chloride,sulfate and nitrate are soluble. In water solutions, In3+ and [InO2]- ions are hydrolyzed to give InOH2+ and HInO2due to generally amphoteric character of indium(III) ions. Indium(III) compounds are not well-soluble, similarly tothallium(III) compounds; however, indium(III) salts of strong acids, such as chloride, sulfate and nitrate are soluble,hydrolyzing in water solutions. The In3+ ion is colorless in solution because of the absence of unpaired electrons inthe d- and f-electron shells.[6]

Indium(I) compounds are not as common as indium(III) ones; only chloride, bromide, iodide, sulfide andcyclopentadienyl are well-characterized. Indium(I) sulfide is the product of reaction between indium and sulfur orindium and hydrogen sulfide, and can be received at 700—1000 °C. Indium(I) oxide black powder is received at850 °C during reaction between indium and carbon dioxide or during decomposition of indium(III) oxide at 1200 °C.Cyclopentadienylindium(I), which was the first organoindium(I) compound reported,[8] is polymer consisting ofzigzag chains of alternating indium atoms and cyclopentadienyl complexes.Less frequently, indium shows intermediate oxidation state +2, which lies between the common ones, most notablyin halides, In2X4 and [In2X6]2-.[9] Several other compounds are known to combine indium(I) and indium(III), such asInI

6(InIIICl6)Cl3,[10] InI5(InIIIBr4)2(InIIIBr6),[11] InIInIIIBr4.[9]

IsotopesIndium occurs naturally on Earth only in two primordial nuclides, indium-113 and indium-115. Out of this two,indium-115 makes up 95.7% of all indium but it is radioactive, decaying to tin-115 via beta decay with half-life of4.41×1014 years, four orders of magnitude larger than the age of the universe and nearly 50,000 times longer thanthat of natural thorium.[12] This effect is uncommon among stable chemical elements; only indium, tellurium, andrhenium have been shown that their most abundant isotopes are radioactive. However, the less common naturalisotope of indium, indium-113, is stable.Indium has 39 known isotopes, ranging in mass between 97 and 135. Only one of them is stable and one has half-lifeexceeding 1014 years; the most stable other indium isotope is indium-111, which has half-life of approximately 2.8days. All other isotopes have half-lives shorter than 5 hours. Indium also has 47 meta states, out of whichindium-114m1 is the most stable, being more stable than ground state of any indium isotope, except for theprimordial ones.

Creation and occurrence

The s-process acting in the range from silver to antimony.

Indium is created via the long-lasting,(up to thousands of years), s-process inlow-medium mass stars (which rangein mass between 0.6 and 10 masses ofSun). When a silver-109 atom, whichcomprises approximately half of allsilver in existence, catches a neutron, itundergoes a beta decay to becomecadmium-110. Capturing furtherneutrons, it becomes cadmium-115,which decays to indium-115 viaanother beta decay. This explains whythe radioactive isotope predominates in abundance compared to the stable one.[13]

Indium is 61st most abundant element in the Earth's crust at approximately 49 ppb, making indium approximately as abundant as mercury.[14] Fewer than 10 indium minerals are known, such as dzhalindite (In(OH)3) and indite

Indium 63

(FeIn2S4),[15] but none of these occurs in significant deposits.Based on content of indium in zinc ore stocks, there is a worldwide reserve base of approximately 6,000 tonnes ofeconomically viable indium.[16] This figure has led to estimates suggesting that, at current consumption rates, there isonly 13 years' supply of indium left.[17] However, the Indium Corporation, the largest processor of indium, claimsthat, on the basis of increasing recovery yields during extraction, recovery from a wider range of base metals(including tin, copper and other polymetallic deposits) and new mining investments, the long-term supply of indiumis sustainable, reliable and sufficient to meet increasing future demands.[18]

This conclusion may be reasonable considering that silver, which is one-third as abundant as indium in the Earth'scrust,[19] is currently mined at approximately 18,300 tonnes per year,[20] which is 40 times greater than currentindium mining rates.

HistoryIn 1863, the German chemists Ferdinand Reich and Hieronymous Theodor Richter were testing ores from the minesaround Freiberg, Saxony. They dissolved the minerals pyrite, arsenopyrite, galena and sphalerite in hydrochloric acidand distilled the raw zinc chloride. As it was known that ores from that region sometimes contain thallium theysearched for the green emission lines with spectroscopic methods. The green lines were absent but a blue line waspresent in the spectrum. As no element was known with a bright blue emission they concluded that a new elementwas present in the minerals. They named the element with the blue spectral line indium, from the indigo color seenin its spectrum.[21] [22] Richter went on to isolate the metal in 1864.[23] At the World Fair 1867 an ingot of 0.5 kg(1.1 lb) was presented.[24]

In 1924, indium was found to have a valuable ability to stabilize non-ferrous metals, which was its first significantuse for the element.[25] It took until 1936 that the U.S. Bureau of Mines list indium as a commodity, and even inearly 1950s only very limited applications for indium were known, the most of which was making light-emittingdiodes and engines for aircrafts during the World War II. The start of production of indium containingsemiconductors started in 1952. The development and widespread use of indium containing nuclear control rodsincreased the demand during the 1970s, the use of indium tin oxide in liquid crystal displays increased and becamethe major application by 1992.[26] [27] [28] [29] [30]

ProductionThe lack of indium mineral deposits and the fact that indium is enriched in sulfidic lead, tin, copper, iron andpredominately in zinc deposits, makes zinc production the main source for indium. The indium is leached from slagand dust of zinc production. Further purification is done by electrolysis.[24]

Indium is produced mainly from residues generated during zinc ore processing but is also found in iron, lead, andcopper ores.[2] China is a leading producer of indium. The Teck Cominco refinery in Trail, British Columbia, is alarge single source indium producer, with production of 32,500 kg in 2005, 41,800 kg in 2004 and 36,100 kg in2003. South American Silver Corporation's Malku Khota property in Bolivia is a large resource of indium with anindicated resource of 1,481 tonnes and inferred resource of 935 tonnes.[31] Adex Mining Inc.’s Mount Pleasant Minein New Brunswick, Canada, holds some of the world’s total known indium resources.[32]

The amount of indium consumed is largely a function of worldwide LCD production. Worldwide production is currently 476 tonnes per year from mining and a further 650 tonnes per year from recycling.[18] Demand has risen rapidly in recent years with the popularity of LCD computer monitors and television sets, which now account for 50% of indium consumption.[33] Increased manufacturing efficiency and recycling (especially in Japan) maintain a balance between demand and supply. According to the UNEP, indium's end-of-life recycling rate is less than 1%.[34]

Demand increased as the metal is used in LCDs and televisions, and supply decreased when a number of Chinese mining concerns stopped extracting indium from their zinc tailings. In 2002, the price was US$94 per kilogram. The

Indium 64

recent changes in demand and supply have resulted in high and fluctuating prices of indium, which from 2006 to2009 ranged from US$382/kg to US$918/kg.

Applications

A magnified image of an LCD screen showingRGB pixels. Individual transistors are seen as

white dots in the bottom part.

The first large-scale application for indium was as a coating forbearings in high-performance aircraft engines during World War II.Afterward, production gradually increased as new uses were found infusible alloys, solders, and electronics. In the 1950s, tiny beads of itwere used for the emitters and collectors of PNP alloy junctiontransistors. In the middle and late 1980s, the development of indiumphosphide semiconductors and indium tin oxide thin films for liquidcrystal displays (LCD) aroused much interest. By 1992, the thin-filmapplication had become the largest end use.[35] [36]

Electronics

• Indium oxide (In2O3) and indium tin oxide (ITO) are used as atransparent conductive coating applied to glass substrates in themaking of electroluminescent panels.[37]

• Some indium compounds such as indium antimonide, indiumphosphide,[38] and indium nitride[39] are semiconductors with usefulproperties.

• Indium is used in the synthesis of the semiconductor copper indiumgallium selenide (CIGS), which is used for the manufacture of thinfilm solar cells.[40]

• Used in light-emitting diodes (LEDs) and laser diodes based on compound semiconductors such as InGaN, InGaPthat are fabricated by Metalorganic Vapor Phase Epitaxy (MOVPE) technology.[41]

• Ultrapure metalorganics of indium include high purity trimethylindium (TMI), which is used as a precursor inIII-V compound semiconductors, while it is also used as the semiconductor dopant in II-VI compoundsemiconductors.[42]

• One of many substitutes for mercury in alkaline batteries to prevent the zinc from corroding and releasinghydrogen gas.[43]

Metal and alloys

Ductile indium wire

• Very small amounts used in aluminium alloy sacrificial anodes (forsalt water applications) to prevent passivation of the aluminium.

• To bond gold electrical test leads to superconductors, indium is usedas a conducting adhesive and applied under a microscope withprecision tweezers.[44]

• In the form of a wire it is used as a vacuum seal and a thermalconductor in cryogenics and ultra-high vacuum applications. Forexample, in manufacturing gaskets which deform to fill gaps.[45]

• Used as a calibration material for Differential scanningcalorimetry.[46]

• It is an ingredient in the gallium-indium-tin alloy Galinstan, which is liquid at room temperature while not beingtoxic like mercury.[47]

Indium 65

Other uses• Indium tin oxide is used as a light filter in low pressure sodium vapor lamps. The infrared radiation is reflected

back into the lamp, which increases the temperature within the tube and therefore improves the performance ofthe lamp.[36]

• Indium's melting point of 429.7485 K (156.5985 °C) is a defining fixed point on the international temperaturescale ITS-90.[48]

• Indium's high neutron capture cross section for thermal neutrons makes it suitable for use in control rods fornuclear reactors, typically in an alloy containing 80% silver, 15% indium, and 5% cadmium.[49]

• In nuclear engineering, the (n,n') reactions of 113In and 115In are used to determine magnitudes of neutronfluxes.[50]

• Indium is also used as a thermal interface material by personal computer enthusiasts in the form of pre-shaped foilsheets fitted between the heat-transfer surface of a microprocessor and its heat sink. The application of heatpartially melts the foil and allows the indium metal to fill in any microscopic gaps and pits between the twosurfaces, removing any insulating air pockets that would otherwise compromise heat transfer efficiency.[51]

• 111In emits gamma radiation and is used in indium leukocyte imaging, or indium scintigraphy, a technique ofmedical imaging that is particularly helpful in differentiating conditions such as osteomyelitis from decubitusulcers for assessment of route and duration of antibiotic therapy.[52] Indium leukocyte scintigraphy has manyapplications, including early phase drug development, and the monitoring of activity of white blood cells. For thetest, blood is taken from the patient, white cells removed, labeled with the radioactive 111In, then re-injected backinto the patient. Gamma imaging will then reveal any areas of on-going white cell localization such as new anddeveloping areas of infection.

Precautions and health issuesPure indium in metal form is considered non-toxic by most sources. In the welding and semiconductor industries,where indium exposure is relatively high, there have been no reports of any toxic side-effects. Indium compounds,like aluminum compounds, complex with hydroxyls to form insoluble salts in basic conditions, and are thus notwell-absorbed from food, giving them fairly low oral toxicty. Soluble indium(III) is toxic when deliveredparenterally, however, causing damage primarily to the kidney (both inner and outer parts), but additionally to heartand liver, and may be teratogenic.[53] Other indium compounds are toxic when administered outside thegastrointestinal tract: for example, anhydrous indium trichloride (InCl3) and indium phosphide (InP) are quite toxicwhen delivered into the lungs (the latter is a suspected carcinogen).[54] [55]

References[1] Magnetic susceptibility of the elements and inorganic compounds (http:/ / www-d0. fnal. gov/ hardware/ cal/ lvps_info/ engineering/

elementmagn. pdf), in Handbook of Chemistry and Physics 81st edition, CRC press.[2] Alfantazi, A. M.; Moskalyk, R. R. (2003). "Processing of indium: a review". Minerals Engineering 16 (8): 687–694.

doi:10.1016/S0892-6875(03)00168-7.[3] Dean, John A. (523). Lange's handbook of chemistry (Fifteenth edition). McGraw-Hill, Inc. ISBN 0070161909.[4] (German)Holleman, Arnold F.; Wiberg, Egon; Wiberg, Nils (1985). "Thallium". Lehrbuch der Anorganischen Chemie (91–100 ed.).

Walter de Gruyter. pp. 892–893. ISBN 3110075113.[5] Handbook of Chemistry and Physics 91st edition, pg 8–20[6] (Russian)Bleshinsky, S. V.; Abramova, V. F. (1958). Химия индия. Frunze. p. 252.[7] (Russian)Bleshinsky, S. V.; Abramova, V. F. (1958). Химия индия. Frunze. p. 301.[8] Fischer, E. O.; Hofmann, H. P. (1957). "Metall-cyclopentadienyle des Indiums" (in German). Angewandte Chemie 69 (20): 639–640.

doi:10.1002/ange.19570692008.[9] Sinclair, Ian; Worrall, Ian J. (1982). "Neutral complexes of the indium dihalides". Canadian Journal of Chemistry 60 (6): 695–698.

doi:10.1139/v82-102.[10] Beck, Horst Philipp; Wilhelm, Doris (1991). "In7Cl9—A New"Old" Compound in the System In-Cl". Angewandte Chemie International

Edition in English 30 (7): 824–825. doi:10.1002/anie.199108241.

Indium 66

[11] Dronskowski, Richard (1995). "Synthesis, Structure, and Decay of In4Br7". Angewandte Chemie International Edition in English 34 (10):1126–1128. doi:10.1002/anie.199511261.

[12] Audi, Georges (2003). "The NUBASE Evaluation of Nuclear and Decay Properties". Nuclear Physics A (Atomic Mass Data Center) 729:3–128. Bibcode 2003NuPhA.729....3A. doi:10.1016/j.nuclphysa.2003.11.001.

[13] A. I. Boothroyd (2006). "Heavy elements in stars". Science 314 (5806): 1690–1691. doi:10.1126/science.1136842. PMID 17170281.[14] "Elements, Terrestrial Abundance" (http:/ / www. daviddarling. info/ encyclopedia/ E/ elterr. html). www.daviddarling.info. . Retrieved

2007-04-14.[15] Sutherland, J. K. (1971). "A second occurrence of dzhalindite" (http:/ / canmin. geoscienceworld. org/ cgi/ content/ abstract/ 10/ 5/ 781). The

Canadian Mineralogist 10 (5): 781–786. .[16] "Mineral Commodities Summary 2007: Indium" (http:/ / minerals. usgs. gov/ minerals/ pubs/ commodity/ indium/ indiumcs07. pdf) (pdf).

United States Geological Survey. . Retrieved 2007-12-26.[17] Reilly, Michael (May 26, 2007). "How Long Will it Last?" (http:/ / environment. newscientist. com/ channel/ earth/ mg19426051.

200-earths-natural-wealth-an-audit. html). New Scientist 194 (2605): 38–39. Bibcode 2007NewSc.194...38R.doi:10.1016/S0262-4079(07)61508-5. ISSN 0262-4079. .

[18] "Indium and Gallium Supply Sustainability September 2007 Update" (http:/ / www. indium. com/ _dynamo/ download. php?docid=552)(pdf). 22nd EU PV Conference, Milan, Italy. . Retrieved 2007-12-26.

[19] "Indium Price Supported by LCD Demand and New Uses for the Metal" (http:/ / geology. com/ articles/ indium. shtml). September 6, 2009..

[20] "Top World Silver Producers" (http:/ / www. nma. org/ pdf/ g_silver_producers. pdf) (pdf). World Silver Survey 2007. .[21] Reich, F.; Richter, T. (1863). "Ueber das Indium" (in German). Journal für Praktische Chemie 90 (1): 172–176.

doi:10.1002/prac.18630900122.[22] Venetskii, S. (1971). "Indium". Metallurgist 15 (2): 148–150. doi:10.1007/BF01088126.[23] Reich, F.; Richter, T. (1864). "Ueber das Indium" (in German). Journal für Praktische Chemie 92 (1): 480–485.

doi:10.1002/prac.18640920180.[24] Schwarz-Schampera, Ulrich; Herzig, Peter M. (2002). Indium: Geology, Mineralogy, and Economics (http:/ / books. google. com/

?id=k7x_2_KnupMC& pg=PA1). Springer. ISBN 9783540431350. .[25] French, Sidney J. (1934). "A story of indium". Journal of Chemical Education 11 (5): 270. doi:10.1021/ed011p270.[26] Schwarz-Schampera, Ulrich; Herzig, Peter M; Rohstoffe, Bundesanstalt für Geowissenschaften und (2002-06-10). "history" (http:/ / books.

google. com/ books?id=k7x_2_KnupMC& pg=PA1). Indium: Geology, mineralogy, and economics. p. 1. ISBN 9783540431350. .[27] Weeks, R.A. (1973). "Gallium, germanium, and indium" (http:/ / ia600402. us. archive. org/ 30/ items/ unitedstatesmine00brob/

unitedstatesmine00brob. pdf). In Brobst, Donald Albert; Pratt, Walden P.. Mines and mineral resources. pp. 237–246. .[28] Jorgenson, John D.; George, Micheal W.. "Mineral Commodity Profile Indium" (http:/ / pubs. usgs. gov/ of/ 2004/ 1300/ 2004-1300. pdf).

United States Geological Survey. .[29] "Canadian Minerals Yearbook" (http:/ / www. nrcan. gc. ca/ mms-smm/ busi-indu/ cmy-amc/ content/ 2007/ 31. pdf). 2007. .[30] "Recycling Rates of Metals: A Status Report" (http:/ / www. unep. org/ resourcepanel/ metals_recycling/ files/ pdf/

Metals_Recycling_Rates_110412. pdf). United Nations Environmental Programme. . Retrieved August 2, 2011.[31] "Malku Khota Updated Preliminary Economic Assessment, May 2011" (http:/ / soamsilver. com/ upload/ Technical_Reports/

Malku_Khota_PEA_Update_11_May_2011. pdf. pdf). South American Silver Corp.. .[32] Wright, Philip (1996). "Mineral and Metal Commodity Review: Tin." (http:/ / www. rncan. gc. ca/ smm-mms/ busi-indu/ cmy-amc/ content/

1996/ 61. pdf). Natural Resources Canada. . Retrieved 2011-06-01.[33] "Indium Price Supported by LCD Demand and New Uses for the Metal" (http:/ / geology. com/ articles/ indium. shtml) (pdf). Geology.com.

. Retrieved 2007-12-26.[34] "USGS Mineral Commodity Summaries 2011" (http:/ / minerals. usgs. gov/ minerals/ pubs/ mcs/ 2011/ mcs2011. pdf). USGS and USDI. .

Retrieved August 2, 2011.[35] Tolcin, Amy C.. "Mineral Yearbook 2007: Indium" (http:/ / minerals. usgs. gov/ mineralofthemonth/ indium. pdf) (pdf). United States

Geological Survey. . Retrieved 200-02-03.[36] Downs, Anthony John (1993). Chemistry of Aluminium, Gallium, Indium, and Thallium (http:/ / books. google. com/ ?id=v-04Kn758yIC).

Springer. pp. 89 and 106. ISBN 9780751401035. .[37] "The Electroluminescent Light Sabre" (http:/ / www. azonano. com/ news. asp?newsID=1007). Nanotechnology News Archive. Azonano.

June 2, 2005. . Retrieved 2007-08-29.[38] Bachmann, K. J. (1981). "Properties, Preparation, and Device Applications of Indium Phosphide". Annual Review of Materials Science 11:

441–484. Bibcode 1981AnRMS..11..441B. doi:10.1146/annurev.ms.11.080181.002301.[39] Bhuiyan, Ghani; Hashimoto, Akihiro; Yamamoto, Akioare (2003). "Indium nitride (InN): A review on growth, characterization, and

properties". Journal of Applied Physics 94 (5): 2779. Bibcode 2003JAP....94.2779B. doi:10.1063/1.1595135.[40] Powalla, M.; Dimmler, B. (2000). "Scaling up issues of CIGS solar cells". Thin Solid Films 361–362: 540–546.

Bibcode 2000TSF...361..540P. doi:10.1016/S0040-6090(99)00849-4.[41] E. Fred Schubert (2003). Light-Emitting Diodes. Cambridge University Press. p. 16. ISBN 0-521-53351-1.[42] Shenai, Deodatta V.; Timmons, Michael L.; DiCarlo Jr., Ronald L.; Marsman, Charles J. (2004). "Correlation of film properties and reduced

impurity concentrations in sources for III/V-MOVPE using high-purity trimethylindium and tertiarybutylphosphine". Journal of Crystal

Indium 67

Growth 272 (1–4): 603–608. Bibcode 2004JCrGr.272..603S. doi:10.1016/j.jcrysgro.2004.09.006.[43] Geological Survey (U.S.) (2010). Minerals Yearbook, 2008, V. 1, Metals and Minerals. Government Printing Office. p. 35-2.

ISBN 9781411330153.[44] Rabilloud, Guy (1997). High-performance Polymers: Conductive adhesives. Editions TECHNIP. p. 263. ISBN 2710807165.[45] ed. by G. L. Weissler ... (1990). Vacuum physics and technology (http:/ / books. google. com/ ?id=tfLWfAx1ZWQC& pg=PA296). San

Diego: Acad. Press. p. 296. ISBN 9780124759145. .[46] Reading, Mike; Hourston, Douglas J. (2006). Modulated temperature differential scanning calorimetry. Springer. p. 245.

ISBN 978140203749X.[47] Surmann, P; Zeyat, H (Nov 2005). "Voltammetric analysis using a self-renewable non-mercury electrode". Analytical and bioanalytical

chemistry 383 (6): 1009–13. doi:10.1007/s00216-005-0069-7. PMID 16228199.[48] Preston-Thomas, H. (1990). "Procès-Verbaux du Comité International des Poids et Mesures". Metrologia 27 (1): 3–10.

Bibcode 1990Metro..27....3P. doi:10.1088/0026-1394/27/1/002.[49] Scoullos, Michael J (2001-12-31). "Other types of cadmium alloys" (http:/ / books. google. de/ books?id=9yzN-QGag_8C& pg=PA222).

Mercury, cadmium, lead: handbook for sustainable heavy metals policy and regulation. p. 222. ISBN 9781402002243. .[50] Berger, Harold; National Bureau Of Standards, United States; Committee E-7 On Nondestructive Testing, American Society for Testing and

Materials (1976). "Image Detectors for Other Neutron Energies" (http:/ / books. google. de/ books?id=b1ZwQXdxAtUC& pg=PA50).Practical applications of neutron radiography and gaging: a symposium. pp. 50–51. .

[51] Tong, Xingcun Colin (2011). Advanced Materials for Thermal Management of Electronic Packaging. Springer. p. 323.ISBN 9781441977595.

[52] Van Nostrand, D.; Abreu, S. H.; Callaghan, J. J.; Atkins, F. B.; Stoops, H. C.; Savory, C. G. (May 1988). "In-111-labeled white blood celluptake in noninfected closed fracture in humans: prospective study" (http:/ / radiology. rsna. org/ content/ 167/ 2/ 495. short). Radiology(Radiological Society of North America, Inc.) 167 (2): 495–498. PMID 3357961. . Retrieved July 20, 2011.

[53] Lenntech (1998). "Indium". Lenntech.com.[54] Tanaka, A.; Hirata, M.; Omura, M., (2002). "Pulmonary toxicity of indium-tin oxide and indium phosphide after intratracheal instillations

into the lung of hamsters". Journal of the Occupational Health 44 (2): 99–102. doi:10.1539/joh.44.99.[55] Blazka, M. E.; Dixon, D., Haskins, E., Rosenthal, G. J. (1994). "Pulmonary toxicity to intratracheally administered indium trichloride in

Fischer 344 rats". Fundamental Applied Toxicology 22 (2): 231–239. doi:10.1006/faat.1994.1027.

External links• WebElements.com – Indium (http:/ / www. webelements. com/ webelements/ elements/ text/ In/ index. html)• Reducing Agents > Indium low valent (http:/ / www. organic-chemistry. org/ chemicals/ reductions/

indiumlowvalent. shtm)

Thallium 68

Thallium

Thallium

Appearance

silvery white

General properties

Name, symbol, number thallium, Tl, 81

Pronunciation /ˈθæliəm/thal-ee-əm

Element category post-transition metal

Group, period, block 13, 6, p

Standard atomic weight 204.3833 g·mol−1

Electron configuration [Xe] 4f14 5d10 6s2 6p1

Electrons per shell 2, 8, 18, 32, 18, 3 (Image)

Physical properties

Phase solid

Density (near r.t.) 11.85 g·cm−3

Liquid density at m.p. 11.22 g·cm−3

Melting point 577 K,304 °C,579 °F

Boiling point 1746 K,1473 °C,2683 °F

Heat of fusion 4.14 kJ·mol−1

Heat of vaporization 165 kJ·mol−1

Specific heat capacity (25 °C) 26.32 J·mol−1·K−1

Vapor pressure

P/Pa 1 10 100 1 k 10 k 100 k

at T/K 882 977 1097 1252 1461 1758

Atomic properties

Oxidation states 3, 1 (mildly basic oxide)

Electronegativity 1.62 (Pauling scale)

Ionization energies 1st: 589.4 kJ·mol−1

2nd: 1971 kJ·mol−1

3rd: 2878 kJ·mol−1

Thallium 69

Atomic radius 170 pm

Covalent radius 145±7 pm

Van der Waals radius 196 pm

Miscellanea

Crystal structure hexagonal

Magnetic ordering diamagnetic[1]

Electrical resistivity (20 °C) 0.18 µΩ·m

Thermal conductivity (300 K) 46.1 W·m−1·K−1

Thermal expansion (25 °C) 29.9 µm·m−1·K−1

Speed of sound (thin rod) (20 °C) 818 m/s

Young's modulus 8 GPa

Shear modulus 2.8 GPa

Bulk modulus 43 GPa

Poisson ratio 0.45

Mohs hardness 1.2

Brinell hardness 26.4 MPa

CAS registry number 7440-28-0

Most stable isotopes

iso NA half-life DM DE (MeV) DP

203Tl 29.524% 203Tl is stable with 122 neutron

204Tl syn 119 Ms(3.78 y)

β− 0.764 204Pb

ε 0.347 204Hg

205Tl 70.476% 205Tl is stable with 124 neutron

Thallium (  /ˈθæliəm/ thal-ee-əm) is a chemical element with the symbol Tl and atomic number 81. This softgray poor metal resembles tin but discolors when exposed to air. The two chemists William Crookes andClaude-Auguste Lamy discovered thallium independently in 1861 by the newly developed method of flamespectroscopy. Both discovered the new element in residues of sulfuric acid production.Approximately 60–70% of thallium production is used in the electronics industry, and the remainder is used in thepharmaceutical industry and in glass manufacturing.[2] It is also used in infrared detectors. Thallium is highly toxicand was used in rat poisons and insecticides. Its use has been reduced or eliminated in many countries because of itsnonselective toxicity. Because of its use for murder, thallium has gained the nicknames "The Poisoner's Poison" and"Inheritance Powder" (alongside arsenic).[3]

Thallium 70

CharacteristicsThallium is extremely soft and malleable and can be cut with a knife at room temperature. It has a metallic luster, butwhen exposed to air, it quickly tarnishes with a bluish-gray tinge that resembles lead. It may be preserved byimmersing it in oil. A heavy layer of oxide builds up on thallium if left in air. In the presence of water, thalliumhydroxide is formed. Sulfuric and nitric acid dissolve thallium rapidly to make the sulfate and nitrate salts, whilehydrochloric acid forms an insoluble thallium(I) chloride layer.[4] Its standard electrode potential is -0.34, slightlyhigher than the potential for iron (at -0.44).

IsotopesThallium has 25 isotopes which have atomic masses that range from 184 to 210. 203Tl and 205Tl are the only stableisotopes, and 204Tl is the most stable radioisotope, with a half-life of 3.78 years.[5]

202Tl (half-life 12.23 days) can be made in a cyclotron,[6] while 204Tl is made by the neutron activation of stablethallium in a nuclear reactor.[5] [5] [7]

201Tl (half-life 73 hrs), decays by electron capture, emitting Hg X-rays (~70–80 keV), and photons of 135 and167 keV in 10% total abundance;[5] therefore it has good imaging characteristics without excessive patient radiationdose. It is the most popular isotope used for thallium nuclear cardiac stress tests.[8]

208Tl (half-life 3.05 minutes) is generated in the naturally-occurring thorium decay chain. It's prominent 2615 keVgamma ray is the dominant high-energy feature observed in natural background radiation.

ChemistryThe two main oxidation states of thallium are +1 and +3. In the oxidation state +1 most compounds closely resemblethe corresponding potassium or silver compounds (The ionic radius of thallium(I) is 1.47 Å while that of potassiumis 1.33 Å and that of silver is 1.26 Å). For example, the water-soluble and very basic thallium(I) hydroxide reactswith carbon dioxide forming water-soluble thallium carbonate This carbonate is the only water soluble heavy metalcarbonate. The similarity with silver compounds is observed with the halide, oxide, and sulfide compounds.Thallium(I) bromide is a photosensitive yellow compound very similar to the silver bromide, while the blackthallium(I) oxide and thallium(I) sulfide are very similar to the silver oxide and silver sulfide.The compounds with oxidation state +3 resemble the corresponding aluminium(III) compounds. They aremoderately strong oxidizing agents, as illustrated by the reduction potential of +0.72 volts for Tl3+ + 3 e– → Tl(s).The thallium(III) oxide is a black solid which decomposes above 800 °C, forming the thallium(I) oxide andoxygen.[4]

HistoryThallium (Greek θαλλός, thallos, meaning "a green shoot or twig")[9] was discovered by flame spectroscopy in1861.[10] The name comes from thallium's bright green spectral emission lines.[11]

After the publication of the improved method of flame spectroscopy by Robert Bunsen and Gustav Kirchhoff[12] and the discovery of caesium and rubidium in the years 1859 to 1860, flame spectroscopy became an approved method to determine the composition of minerals and chemical products. William Crookes and Claude-Auguste Lamy both started to use the new method. William Crookes used it to make spectroscopic determinations for tellurium on selenium compounds deposited in the lead chamber of a sulfuric acid production plant near Tilkerode in the Harz mountains. He had obtained the samples for his research on selenium cyanide from August Hofmann years earlier.[13] [14] By 1862, Crookes was able to isolate small quantities of the new element and determine the properties of a few compounds.[15] Claude-Auguste Lamy used a similar spectrometer to Crookes' to determine the composition of a selenium-containing substance which was deposited during the production of sulfuric acid from pyrite. He also noticed the new green line in the spectra and concluded that a new element was present. Lamy had received this

Thallium 71

material from the sulfuric acid plant of his friend Fréd Kuhlmann and this by-product was available in largequantities. Lamy started to isolate the new element from that source.[16] The fact that Lamy was able to work amplequantities of thallium enabled him to determine the properties of several compounds and in addition he prepared asmall ingot of metallic thallium which he prepared by remelting thallium he had obtained by electrolysis of thalliumsalts.As both scientists discovered thallium independently and a large part of the work, especially the isolation of themetallic thallium was done by Lamy, Crookes tried to secure his priority on the work. Lamy was awarded a medal atthe International Exhibition in London 1862: For the discovery of a new and abundant source of thallium and afterheavy protest Crookes also received a medal: thallium, for the discovery of the new element. The controversybetween both scientists continued through 1862 and 1863. Most of the discussion ended after Crookes was electedFellow of the Royal Society in June 1863.[17] [18]

The dominant use of thallium was the use as poison for rodents. After several accidents the use as poison was bannedin the United States by the Presidential Executive Order 11643 in February 1972. In the subsequent years severalother countries also banned the use.[19]

Occurrence and productionAlthough thallium is a modestly abundant element in the Earth's crust, with a concentration estimated to be about0.7 mg/kg,[20] mostly in association with potassium-based minerals in clays, soils, and granites, thallium is notgenerally economically recoverable from these sources. The major source of thallium for practical purposes is thetrace amount that is found in copper, lead, zinc, and other heavy-metal-sulfide ores.[21] [22]

Crystals of hutchinsonite (TlPbAs5S9)

Thallium is found in the minerals crookesite TlCu7Se4, hutchinsoniteTlPbAs5S9, and lorandite TlAsS2.[23] Thallium also occurs as a traceelement in iron pyrite, and thallium is extracted as a by-product ofroasting this mineral for the production of sulfuric acid.[2] [24]

Thallium can also be obtained from the smelting of lead and zinc ores.Manganese nodules found on the ocean floor also contain somethallium, but the collection of these nodules has been and continues tobe prohibitively expensive. There is also the potential for damaging theenvironment of the oceans.[25] In addition, several other thalliumminerals, containing 16% to 60% thallium, occur in nature as

complexes of sulfides or selenides that primarily contain antimony, arsenic, copper, lead, and/or silver. However,these minerals are rare, and they have had no commercial importance as sources of thallium.[20] The Allchar depositin southern Macedonia was the only area where thallium was ever actively mined. This deposit still contains aloosely estimated 500 tonnes of thallium, and it is a source for several rare thallium minerals, for examplelorandite.[26]

The United States Geological Survey (USGS) estimates that the annual worldwide production of thallium is about 10 metric tonnes as a by-product from the smelting of copper, zinc, and lead ores.[20] Thallium is either extracted from the dusts from the smelter flues or from residues such as slag that are collected at the end of the smelting process.[20] The raw materials used for thallium production contain large amounts of other materials and therefore a purification is the first step. The thallium is leached either by the use of a base or sulfuric acid from the material. The thallium is several times precipitated from the solution and to remove further impurities. At the end it is converted to thallium sulfate and the thallium is extracted by electrolysis on platinum or stainless steel plates.[24] The production of thallium decreased by about 33% in the period from 1995 to 2009 – from about 15 metric tonnes to about 10 tonnes. Since there are several small deposits or ores with relatively high thallium content, it would be possible to increase the production of it if a new application, such as a hypothetical thallium-containing high-temperature

Thallium 72

superconductor, becomes practical for widespread use outside of the laboratory.[20]

Applications

Historic usesThe odorless and tasteless thallium sulfate was once widely used as rat poison and ant killer. Since 1972 this use hasbeen prohibited in the United States due to safety concerns.[19] Many other countries followed this example in thefollowing years.[2] Thallium salts were used in the treatment of ringworm, other skin infections and to reduce thenight sweating of tuberculosis patients. However this use has been limited due to their narrow therapeutic index, andthe development of more-advanced medicines for these conditions.[27] [28] [29]

OpticsThallium(I) bromide and thallium(I) iodide crystals have been used as infrared optical materials, because they areharder than other common infrared optics, and because they have transmission at significantly longer wavelengths.The trade name KRS-5 refers to this material.[30] Thallium oxide has been used to manufacture glasses that have ahigh index of refraction. Combined with sulfur or selenium and arsenic, thallium has been used in the production ofhigh-density glasses that have low melting points in the range of 125 and 150 °C. These glasses have roomtemperature properties that are similar to ordinary glasses and are durable, insoluble in water and have uniquerefractive indices.[31]

Electronics

Corroded thallium rod

Thallium(I) sulfide's electrical conductivity changes with exposure toinfrared light therefore making this compound useful inphotoresistors.[27] Thallium selenide has been used in a bolometer forinfrared detection.[32] Doping selenium semiconductors with thalliumimproves their performance, and therefore it is used in trace amounts inselenium rectifiers.[27] Another application of thallium doping is thesodium iodide crystals in gamma radiation detection devices. In these,the sodium iodide crystals are doped with a small amount of thalliumto improve their efficiency as scintillation generators.[33] Some of theelectrodes in dissolved oxygen analyzers contain thallium.[2]

High-temperature superconductivityResearch activity with thallium is ongoing to develop high-temperature superconducting materials for suchapplications as magnetic resonance imaging, storage of magnetic energy, magnetic propulsion, and electric powergeneration and transmission. The research in applications started after the discovery of the first thallium bariumcalcium copper oxide superconductor in 1988.[34]

MedicalBefore the widespread application of technetium-99m in nuclear medicine, the radioactive isotope thallium-201, witha half-life of 73 hours, was the main substance for nuclear cardiography. The nuclide is still used for stress tests forrisk stratification in patients with coronary artery disease (CAD).[35] This isotope of thallium can be generated usinga transportable generator which is similar to the technetium-99m generator.[36] The generator contains lead-201(half-life 9.33 hours) which decays by electron capture to the thallium-201. The lead-201 can be produced in acyclotron by the bombardment of thallium with protons or deuterons by the (p,3n) and (d,4n) reactions.[37] [38]

Thallium 73

Thallium stress test

A thallium stress test is a form of scintigraphy, where the amount of thallium in tissues correlates with tissue bloodsupply. Viable cardiac cells have normal Na+/K+ ion exchange pumps. The Tl+ cation binds the K+ pumps and istransported into the cells. Exercise or dipyridamole induces widening (vasodilation) of normal coronary arteries.This produces coronary steal from areas where arteries are maximally dilated. Areas of infarct or ischemic tissue willremain "cold". Pre- and post-stress thallium may indicate areas which will benefit from myocardial revascularization.Redistribution indicates the existence of coronary steal and the presence of ischemic coronary artery disease.[39]

Other usesA mercury-thallium alloy, which forms a eutectic at 8.5% thallium, is reported to freeze at −60 °C, some 20 °Cbelow the freezing point of mercury. This alloy is used in thermometers and low-temperature switches.[27] In organicsynthesis thallium(III) salts, as thallium trinitrate or triacetate, are useful reagents performing differenttransformations in aromatics, ketones, olefins, among others.[40] Thallium is a constituent of the alloy in the anodeplates in magnesium seawater batteries.[2] Soluble thallium salts are added to gold plating baths to increase the speedof plating and to reduce grain size within the gold layer.[41]

The saturated solution of equal parts of thallium(I) formate (Tl(CHO2)) and thallium(I) malonate (Tl(C3H3O4)) inwater is known as Clerici solution. It is a mobile odorless liquid whose color changes from yellowish to clear uponreducing the concentration of the thallium salts. With the density of 4.25 g/cm3 at 20 °C, Clerici solution is one ofthe heaviest aqueous solutions known. It was used in the 20th century for measuring density of minerals by theflotation method, but the use is discontinued due to the high toxicity and corrosiveness of the solution.[42] [43]

Toxicity

Thallium and its compounds are extremely toxic, and should be handled with great care.There are numerous recorded cases of fatal thallium poisoning.[44] Contact with skin isdangerous, and adequate ventilation should be provided when melting this metal. Thallium(I)compounds have a high aqueous solubility and are readily absorbed through the skin.Exposure to them should not exceed 0.1 mg per m2 of skin in an 8-hour time-weightedaverage (40-hour work week). Thallium is a suspected human carcinogen.[45] For a long timethallium compounds were easily available as rat poison. This fact and that it is water soluble

and nearly tasteless led to frequent intoxications caused by accident or criminal intent.[18]

Treatment and internal decontaminationOne of the main methods of removing thallium (both radioactive and normal) from humans is to use Prussian blue,which is a material which absorbs thallium.[46] Up to 20 g per day of Prussian blue is fed by mouth to the person, andit passes through their digestive system and comes out in the stool. Hemodialysis and hemoperfusion are also used toremove thallium from the blood serum. At later stage of the treatment additional potassium is used to mobilizethallium from the tissue.[47] [48]

Thallium 74

Thallium pollutionAccording to the United States Environmental Protection Agency (EPA), man-made sources of thallium pollutioninclude gaseous emission of cement factories, coal burning power plants, and metal sewers. The main source ofelevated thallium concentrations in water is the leaching of thallium from ore processing operations.[22] [49]

References[1] Magnetic susceptibility of the elements and inorganic compounds (http:/ / www-d0. fnal. gov/ hardware/ cal/ lvps_info/ engineering/

elementmagn. pdf), in Handbook of Chemistry and Physics 81st edition, CRC press.[2] "Chemical fact sheet — Thallium" (http:/ / www. speclab. com/ elements/ thallium. htm). Spectrum Laboratories. April 2001. . Retrieved

2008-02-02.[3] Hasan, Heather (2009). The Boron Elements: Boron, Aluminum, Gallium, Indium, Thallium. Rosen Publishing Group. p. 14.

ISBN 9781435853331.[4] Holleman, Arnold F.; Wiberg, Egon; Wiberg, Nils (1985). "Thallium" (in German). Lehrbuch der Anorganischen Chemie (91–100 ed.).

Walter de Gruyter. pp. 892–893. ISBN 3110075113.[5] Audi, Georges (2003). "The NUBASE Evaluation of Nuclear and Decay Properties". Nuclear Physics A (Atomic Mass Data Center) 729 (1):

3–128. Bibcode 2003NuPhA.729....3A. doi:10.1016/j.nuclphysa.2003.11.001.[6] "Thallium Research" (http:/ / www. hss. energy. gov/ healthsafety/ ohre/ roadmap/ histories/ 0472/ 0472d. html). United States Department of

Energy. . Retrieved 2010-05-13.[7] "Manual for reactor produced radioisotopes" (http:/ / www-pub. iaea. org/ MTCD/ publications/ PDF/ te_1340_web. pdf). International

Atomic Energy Agency. 2003. . Retrieved 2010-05-13.[8] Maddahi, Jamshid; Berman, Daniel (2001). "Detection, Evaluation, and Risk Stratification of Coronary Artery Disease by Thallium-201

Myocardial Perfusion Scintigraphy 155" (http:/ / books. google. com/ ?id=CqQgnHrDxrUC& pg=PA173). Cardiac SPECT imaging (2 ed.).Lippincott Williams & Wilkins. pp. 155–178. ISBN 9780781720076. .

[9] Liddell & Scott, A Greek-English Lexicon (http:/ / perseus. mpiwg-berlin. mpg. de/ cgi-bin/ resolveform?doc=Perseus:text:1999. 04.0057;layout=;query=toc;loc=qallo/ s), sub θαλλος (http:/ / perseus. mpiwg-berlin. mpg. de/ cgi-bin/ resolveform?lookup=qallos&type=begin& lang=greek& searchText=& options=Sort+ Results+ Alphabetically& . submit=Submit& formentry=1& lang=greek)

[10] Thallium was discovered both by William Crookes and by Claude Auguste Lamy, working independently. See: (1) William Crookes (March30, 1861) "On the existence of a new element, probably of the sulphur group," Chemical News, vol. 3, pages 193-194 (http:/ / books. google.com/ books?id=6QcAAAAAMAAJ& pg=PA193& lpg=PA193#v=onepage& q& f=false); reprinted in: Philosophical Magazine, vol. 21,pages 301-305 (http:/ / books. google. com/ books?id=OhyQnaPXF5QC& pg=RA1-PA301& lpg=RA1-PA301#v=onepage& q& f=false)(April 1861); (2) William Crookes (May 18, 1861) "Further remarks on the supposed new metalloid," Chemical News, vol. 3, page 303 (http:// books. google. com/ books?id=6QcAAAAAMAAJ& pg=PA303& lpg=PA303); (3) William Crookes (June 19, 1862) "Preliminaryresearches on thallium," Proceedings of the Royal Society of London, vol. 12, pages 150-159. See also: A. Lamy (May 16, 1862) "Del'existencè d'un nouveau métal, le thallium," Comptes Rendus, vol. 54, pages 1255-1262 (http:/ / gallica2. bnf. fr/ ark:/ 12148/ bpt6k30115.image. r=Comptes+ Rendus+ Hebdomadaires. f1254. langFR).

[11] Weeks, Mary Elvira (1932). "The discovery of the elements. XIII. Supplementary note on the discovery of thallium". Journal of ChemicalEducation 9 (12): 2078. Bibcode 1932JChEd...9.2078W. doi:10.1021/ed009p2078.

[12] G. Kirchhoff, R. Bunsen (1861). "Chemische Analyse durch Spectralbeobachtungen". Annalen der Physik und Chemie 189 (7): 337–381.Bibcode 1861AnP...189..337K. doi:10.1002/andp.18611890702.

[13] Crookes, William (1862 - 1863). "Preliminary Researches on Thallium". Proceedings of the Royal Society of London, 12 (0): 150–159.doi:10.1098/rspl.1862.0030. JSTOR 112218.

[14] Crookes, William (1863). "On Thallium". Philosophical Transactions of the Royal Society of London, 153 (0): 173–192.doi:10.1098/rstl.1863.0009. JSTOR 108794.

[15] DeKosky, Robert K. (1973). "Spectroscopy and the Elements in the Late Nineteenth Century: The Work of Sir William Crookes". TheBritish Journal for the History of Science 6 (4): 400–423. doi:10.1017/S0007087400012553. JSTOR 4025503.

[16] Lamy, Claude-Auguste (1862). "De l'existencè d'un nouveau métal, le thallium" (http:/ / gallica2. bnf. fr/ ark:/ 12148/ bpt6k30115. image.r=Comptes+ Rendus+ Hebdomadaires. f1254. langFR). Comptes Rendus: 1255–. .

[17] James, Frank A. J. L. (1984). "Of 'Medals and Muddles' the Context of the Discovery of Thallium: William Crookes's Early". Notes andRecords of the Royal Society of London 39 (1): 65–90. doi:10.1098/rsnr.1984.0005. JSTOR 531576.

[18] Emsley, John (2006). "Thallium" (http:/ / books. google. com/ ?id=BACSR7TXWhoC). The Elements of Murder: A History of Poison.Oxford University Press. pp. 326–327. ISBN 9780192806000. .

[19] Staff of the Nonferrous Metals Division (1972). "Thallium" (http:/ / digicoll. library. wisc. edu/ cgi-bin/ EcoNatRes/EcoNatRes-idx?type=goto& id=EcoNatRes. MinYB1972v1& page=1358& isize=XL). Minerals yearbook metals, minerals, and fuels. 1.United States Geological Survey. p. 1358. .

[20] Guberman, David E.. "Mineral Commodity Summaries 2010: Thallium" (http:/ / minerals. usgs. gov/ minerals/ pubs/ commodity/ thallium/mcs-2010-thall. pdf). United States Geological Survey. . Retrieved 2010-05-13.

Thallium 75

[21] Zitko, V.; Carson, W. V.; Carson, W. G. (1975). "Thallium: Occurrence in the environment and toxicity to fish". Bulletin of EnvironmentalContamination and Toxicology 13 (1): 23. doi:10.1007/BF01684859. PMID 1131433.

[22] Peter, A; Viraraghavan, T (2005). "Thallium: a review of public health and environmental concerns". Environment International 31 (4):493–501. doi:10.1016/j.envint.2004.09.003. PMID 15788190.

[23] Shaw, D (1952). "The geochemistry of thallium". Geochimica et Cosmochimica Acta 2 (2): 118–154. Bibcode 1952GeCoA...2..118S.doi:10.1016/0016-7037(52)90003-3.

[24] Downs, Anthony John (1993). Chemistry of aluminium, gallium, indium, and thallium (http:/ / books. google. com/ ?id=v-04Kn758yIC).Springer. pp. 90 and 106. ISBN 9780751401035. .

[25] Rehkamper, M (2004). "The mass balance of dissolved thallium in the oceans". Marine Chemistry 85 (3-4): 125–139.doi:10.1016/j.marchem.2003.09.006.

[26] Jankovic, S. (1988). "The Allchar Tl–As–Sb deposit, Yugoslavia and its specific metallogenic features". Nuclear Instruments and Methodsin Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment 271 (2): 286.Bibcode 1988NIMPA.271..286J. doi:10.1016/0168-9002(88)90170-2.

[27] Hammond, C. R.. The Elements, in Handbook of Chemistry and Physics 81st edition. CRC press. ISBN 0849304857.[28] Percival, G. H. (1930). "The Treatment of Ringworm of The Scalp with Thallium Acetate". British Journal of Dermatology 42 (2): 59–69.

doi:10.1111/j.1365-2133.1930.tb09395.x.[29] Galvanarzate, S; Santamaría, A (1998). "Thallium toxicity". Toxicology Letters 99 (1): 1–13. doi:10.1016/S0378-4274(98)00126-X.

PMID 9801025.[30] Rodney, William S.; Malitson, Irving H. (1956). "Refraction and Dispersion of Thallium Bromide Iodide". Journal of the Optical Society of

America 46 (11): 338–346. doi:10.1364/JOSA.46.000956.[31] Kokorina, Valentina F. (1996). Glasses for infrared optics (http:/ / books. google. com/ ?id=jOOSKQHEJdwC& pg=PA52). CRC Press.

ISBN 9780849337857. .[32] Nayer, P. S, Hamilton, O. (1977). "Thallium selenide infrared detector". Appl. Opt. 16 (11): 2942. Bibcode 1977ApOpt..16.2942N.

doi:10.1364/AO.16.002942.[33] Hofstadter, Robert (1949). "The Detection of Gamma-Rays with Thallium-Activated Sodium Iodide Crystals". Physical Review 75 (5):

796–810. Bibcode 1949PhRv...75..796H. doi:10.1103/PhysRev.75.796.[34] Sheng, Z. Z.; Hermann A. M. (1988). "Bulk superconductivity at 120 K in the Tl–Ca/Ba–Cu–O system". Nature 332 (6160): 138–139.

Bibcode 1988Natur.332..138S. doi:10.1038/332138a0.[35] Jain, Diwakar; Zaret, Barry L. (2005). "Nuclear imaging in cardiovascular medicine" (http:/ / books. google. com/ ?id=cY182J9q5NoC&

pg=PA222). In Clive Rosendorff. Essential cardiology: principles and practice (2 ed.). Humana Press. pp. 221–222. ISBN 9781588293701. .[36] Lagunas-Solar, M. C.; Little, F. E.; Goodart, C. D. (1982). Abstract "An integrally shielded transportable generator system for thallium-201

production" (http:/ / www. medscape. com/ medline/ abstract/ 7169272). International Journal of Applied Radiation Isotopes 33 (12):1439–1443. doi:10.1016/0020-708X(82)90183-1. Abstract.

[37] Thallium-201 production (http:/ / www. med. harvard. edu/ JPNM/ physics/ isotopes/ Tl/ Tl201/ prod. html) from Harvard Medical School'sJoint Program in Nuclear Medicine

[38] Lebowitz, E.; Greene, M. W.; Fairchild, R.; Bradley-Moore, P. R.; Atkins, H. L.; Ansari, A. N.; Richards, P.; Belgrave, E. (1975)."Thallium-201 for medical use" (http:/ / jnm. snmjournals. org/ cgi/ content/ abstract/ 16/ 2/ 151). The Journal of Nuclear Medicine 16 (2):151–5. PMID 1110421. .

[39] George J. Taylor (2004). Primary care cardiology (http:/ / books. google. com/ ?id=u_A5BSqsb20C& pg=PA100& dq=thallium+ stress+NA+ / K+ & cd=5#v=onepage& q=thallium stress NA+ / K+ ). Wiley-Blackwell. p. 100. ISBN 1405103868. .

[40] Taylor, Edward Curtis; McKillop, Alexander (1970). "Thallium in organic synthesis". Accounts of Chemical Research 3 (10): 956–960.doi:10.1021/ar50034a003.

[41] Pecht, Michael (1994-03-01). Integrated circuit, hybrid, and multichip module package design guidelines: a focus on reliability (http:/ /books. google. de/ books?id=hDwX3slSvQ4C& pg=PA113). pp. 113–115. ISBN 9780471594468. .

[42] R. H. Jahns (1939). Clerici solution for the specific gravity determination of small mineral grains (http:/ / www. minsocam. org/ ammin/AM24/ AM24_116. pdf). 24. p. 116. .

[43] Peter G. Read (1999). Gemmology (http:/ / books. google. com/ ?id=tfXa13uWiRIC& pg=PA63& lpg=PA63). Butterworth-Heinemann.pp. 63–64. ISBN 0750644117. .

[44] http:/ / www. nj. com/ news/ index. ssf/ 2011/ 02/ thallium_is_favored_method_of. html[45] "Biology of Thallium" (http:/ / www. webelements. com/ webelements/ elements/ text/ Tl/ biol. html). webelemnts. . Retrieved 2008-11-11.[46] Yang, Y; Faustino, P; Progar, J; Brownell, C; Sadrieh, N; May, J; Leutzinger, E; Place, D et al. (2008). "Quantitative determination of

thallium binding to ferric hexacyanoferrate: Prussian blue☆". International Journal of Pharmaceutics 353 (1-2): 187–94.doi:10.1016/j.ijpharm.2007.11.031. PMID 18226478.

[47] Prussian blue fact sheet (http:/ / www. bt. cdc. gov/ radiation/ prussianblue. asp) from the Centers for Disease Control and Prevention[48] Malbrain, Manu L. N. G.; Lambrecht, Guy L. Y.; Zandijk, Erik; Demedts, Paul A.; Neels, Hugo M.; Lambert, Willy; De Leenheer, André

P.; Lins, Robert L.; Daelemans, Ronny; (1997). "Treatment of Severe Thallium Intoxication". Clinical Toxicology 35 (1): 97–100.doi:10.3109/15563659709001173. PMID 9022660.

[49] "Factsheet on: Thallium" (http:/ / www. epa. gov/ safewater/ pdfs/ factsheets/ ioc/ thallium. pdf). . Retrieved 2009-09-15.

Thallium 76

External links• Toxicity, thallium (http:/ / www. emedicine. com/ emerg/ topic926. htm)• NLM hazardous substances databank – Thallium, elemental (http:/ / toxnet. nlm. nih. gov/ cgi-bin/ sis/ search/

r?dbs+ hsdb:@term+ @na+ @rel+ thallium,+ elemental)• ATSDR - ToxFAQs (http:/ / www. atsdr. cdc. gov/ tfacts54. html)

Ununtrium 77

Ununtrium

Ununtrium

Appearance

Unknown

General properties

Name, symbol, number ununtrium, Uut, 113

Pronunciation i/uːnˈuːntriəm/oon-oon-tree-əm

Category notes presumably other metals

Group, period, block 13, 7, p

Standard atomic weight [286] g·mol−1

Electron configuration [Rn] 5f14 6d10 7s2 7p1

(guess based on thallium)

Electrons per shell 2, 8, 18, 32, 32, 18, 3 (Image)

Physical properties

Atomic properties

Miscellanea

CAS registry number 54084-70-7

Most stable isotopes

iso NA half-life DM DE (MeV) DP

286Uut syn 19.6 s α 9.63 282Rg

285Uut syn 5.5 s α 9.74,9.48 281Rg

284Uut syn 0.49 s α 10.00 280Rg

283Uut syn 0.10 s α 10.12 279Rg

282Uut syn 73 ms α 10.63 278Rg

278Uut syn 0.34 ms α 11.68 274Rg

Ununtrium is the temporary name of a synthetic element with the temporary symbol Uut and atomic number 113.It is placed as the heaviest member of the group 13 (IIIA) elements although a sufficiently stable isotope is notknown at this time that would allow chemical experiments to confirm its position. It was first detected in 2003 in thedecay of ununpentium and was synthesized directly in 2004. Only fourteen atoms of ununtrium have been observedto date. The longest-lived isotope known is 286Uut with a half-life of ~20 s,[1] allowing first chemical experiments tostudy its chemistry.

Ununtrium 78

History

Discovery profileThe first report of ununtrium was in August 2003 when it was identified as a decay product of ununpentium. Theseresults were published on February 1, 2004, by a team composed of Russian scientists at Dubna (Joint Institute forNuclear Research), and American scientists at the Lawrence Livermore National Laboratory.[2] [3]

On July 23, 2004, a team of Japanese scientists at RIKEN detected a single atom of 278Uut using the cold fusionreaction between bismuth-209 and zinc-70. They published their results on September 28, 2004.[4]

Support for their claim appeared in 2004 when scientists at the Institute of Modern Physics (IMP) identified 266Bh asdecaying with identical properties to their single event (see bohrium).The RIKEN team produced a further atom on April 2, 2005, although the decay data were different from the firstchain, and may be due to the formation of a meta-stable isomer.The Dubna-Livermore collaboration has strengthened their claim for the discovery of ununtrium by conductingchemical experiments on the decay daughter 268Db. In experiments in June 2004 and December 2005, the dubniumisotope was successfully identified by milking the Db fraction and measuring any SF activities. Both the half-life anddecay mode were confirmed for the proposed 268Db which lends support to the assignment of Z=115 and Z=113 tothe parent and daughter nuclei.[5] [6]

Theoretical estimates of alpha-decay half-lives of alpha-decay chains from element 113 are in good agreement withthe experimental data.[7]

NamingThe element with atomic number 113 is historically known as eka-thallium. Ununtrium (Uut) is a temporary IUPACsystematic element name. Research scientists usually refer to the element simply as element 113 (or E113).

Proposed names by claimants

Claims to the discovery of ununtrium have been put forward by Dmitriev of the Dubna team and Morita of theRIKEN team. The IUPAC/IUPAP Joint Working Party will decide to whom the right to suggest a name will begiven. In 2011, the IUPAC has evaluated the 2004 RIKEN experiments and 2004 and 2007 Dubna experiments, andconcluded that they did not meet the criteria for discovery.[8]

The following names have been suggested by the above-mentioned teams claiming discovery:

Group Proposed Name Derivation

RIKEN Japonium[9] Japan: country of group claimants

Rikenium[9] RIKEN: institute of group claimants

Dubna team Becquerelium Henri Becquerel, French physicist

Ununtrium 79

Isotopes and nuclear properties

Nucleosynthesis

Target-projectile combinations leading to Z=113 compound nuclei

The below table contains various combinations of targets and projectiles (both at max no. of neutrons) which couldbe used to form compound nuclei with an atomic number of 113.

Target Projectile CN Attempt result

208Pb 71Ga 279Uut Reaction yet to be attempted

209Bi 70Zn 279Uut Successful reaction

232Th 51V 283Uut Reaction yet to be attempted

238U 45Sc 283Uut Reaction yet to be attempted

237Np 48Ca 285Uut Successful reaction

244Pu 41K 285Uut Reaction yet to be attempted

243Am 40Ar 283Uut Reaction yet to be attempted

248Cm 37Cl 285Uut Reaction yet to be attempted

249Bk 36S 285Uut Reaction yet to be attempted

249Cf 31P 280Uut Reaction yet to be attempted

Cold fusion

This section deals with the synthesis of nuclei of ununtrium by so-called "cold" fusion reactions. These are processeswhich create compound nuclei at low excitation energy (~10–20 MeV, hence "cold"), leading to a higher probabilityof survival from fission. The excited nucleus then decays to the ground state via the emission of one or two neutronsonly.

209Bi(70Zn,xn)279-xUut (x=1)

The synthesis of ununtrium was first attempted in 1998 by the team at GSI using the above cold fusion reaction. Intwo separate runs, they were unable to detect any atoms and calculated a cross section limit of 900 fb.[10] Theyrepeated the experiment in 2003 and lowered the limit further to 400 fb.[10] In late 2003, the emerging team atRIKEN using their efficient apparatus GARIS attempted the reaction and reached a limit of 140 fb. In December2003 – August 2004, they resorted to 'brute force' and performed an eight-month-long irradiation in which theyincreased the sensitivity to 51 fb. They were able to detect a single atom of 278Uut.[4] They repeated the reaction inseveral runs in 2005 and were able to synthesize a second atom. They calculated a record-low 31 fb for the crosssection for the 2 atoms. The reaction was repeated again in 2006 with two long production runs but no further atomswere detected. This lowered the yield further to the current value of just 23 fb.

Ununtrium 80

Hot fusion

This section deals with the synthesis of nuclei of ununtrium by so-called "hot" fusion reactions. These are processeswhich create compound nuclei at high excitation energy (~40–50 MeV, hence "hot"), leading to a reducedprobability of survival from fission. The excited nucleus then decays to the ground state via the emission of 3–5neutrons. Fusion reactions utilizing 48Ca nuclei usually produce compound nuclei with intermediate excitationenergies (~30–35 MeV) and are sometimes referred to as "warm" fusion reactions. This leads, in part, to relativelyhigh yields from these reactions.

237Np(48Ca,xn)285-xUut (x=3)

In June 2006, the Dubna-Livermore team synthesised ununtrium directly in the "warm" fusion reaction betweenneptunium-237 and calcium-48 nuclei. Two atoms of 282Uut were detected with a cross section of 900 fb.[11]

As a decay product

Ununtrium has also been detected in the decay of ununpentium and ununseptium.

Chronology of isotope discovery

Isotope Year discovered Discovery reaction

278Uut 2004 209Bi(70Zn,n) [4]

279Uut unknown

280Uut unknown

281Uut unknown

282Uut 2006 237Np(48Ca,3n)[11]

283Uut 2003 243Am(48Ca,4n)[2]

284Uut 2003 243Am(48Ca,3n)[2]

285Uut 2009 249Bk(48Ca,4n)[1]

286Uut 2009 249Bk(48Ca,3n)[1]

Yields of isotopes

Cold fusion

The table below provides cross-sections and excitation energies for cold fusion reactions producing ununtriumisotopes directly. Data in bold represent maxima derived from excitation function measurements. + represents anobserved exit channel.

Projectile Target CN 1n 2n 3n

70Zn 209Bi 279Uut 23 fb

Ununtrium 81

Hot fusion

The table below provides cross-sections and excitation energies for hot fusion reactions producing ununtriumisotopes directly. Data in bold represents maxima derived from excitation function measurements. + represents anobserved exit channel.

Projectile Target CN 3n 4n 5n

48Ca 237Np 285Uut 0.9 pb, 39.1 MeV [11]

Theoretical calculations

Evaporation residue cross sections

The below table contains various targets-projectile combinations for which calculations have provided estimates forcross section yields from various neutron evaporation channels. The channel with the highest expected yield is given.DNS = Di-nuclear system; σ = cross section

Target Projectile CN Channel (product) σmax

Model Ref

209Bi 70Zn 279Uut 1n (278113) 30 fb DNS [12]

237Np 48Ca 285Uut 3n (282113) 0.4 pb DNS [13]

Chemical properties

Extrapolated chemical properties

Oxidation states

Ununtrium is projected to be the first member of the 7p series of elements and the heaviest member of group 13(IIIA) in the Periodic Table, below thallium. Each of the members of this group show the group oxidation state of+III. However, thallium has a tendency to form only a stable +I state due to the "inert pair effect", explained by therelativistic stabilisation of the 7s-orbitals, resulting in a higher ionisation potential and weaker tendency toparticipate in bonding.

Chemistry

Ununtrium should portray eka-thallium chemical properties and should therefore form a monoxide, Uut2O, andmonohalides, UutF, UutCl, UutBr, and UutI. If the +III state is accessible, it is likely that it is only possible in theoxide, Uut2O3, and fluoride, UutF3. Spin-orbit splitting of the 7p orbitals may stabilize the −1 state as well, as is seenwith gold(−1) (aurides).

References[1] Oganessian, Yu. Ts.; Abdullin, F. Sh.; Bailey, P. D.; Benker, D. E.; Bennett, M. E.; Dmitriev, S. N.; Ezold, J. G.; Hamilton, J. H. et al.

(2010). "Synthesis of a New Element with Atomic Number Z=117". Physical Review Letters 104 (14). Bibcode 2010PhRvL.104n2502O.doi:10.1103/PhysRevLett.104.142502. PMID 20481935.

[2] "Experiments on the synthesis of element 115 in the reaction 243Am(48Ca,xn)291-x115" (http:/ / www. jinr. ru/ publish/ Preprints/ 2003/178(E7-2003-178). pdf), Oganessian et al., JINR Preprints, 2003. Retrieved on 3 March 2008

[3] Oganessian, Yu. Ts.; Utyonkoy, V.; Lobanov, Yu.; Abdullin, F.; Polyakov, A.; Shirokovsky, I.; Tsyganov, Yu.; Gulbekian, G. et al. (2004)."Experiments on the synthesis of element 115 in the reaction 243Am(48Ca,xn)291-x115". Physical Review C 69 (2): 021601.Bibcode 2004PhRvC..69b1601O. doi:10.1103/PhysRevC.69.021601.

[4] Morita, Kosuke; Morimoto, Kouji; Kaji, Daiya; Akiyama, Takahiro; Goto, Sin-Ichi; Haba, Hiromitsu; Ideguchi, Eiji; Kanungo, Rituparna et al. (2004). "Experiment on the Synthesis of Element 113 in the Reaction 209Bi(70Zn, n)278113". Journal of the Physical Society of Japan 73

Ununtrium 82

(10): 2593. Bibcode 2004JPSJ...73.2593M. doi:10.1143/JPSJ.73.2593.[5] "Results of the experiment on chemical identification of Db as a decay product of element 115" (http:/ / www. jinr. ru/ publish/ Preprints/

2004/ 157(e12-2004-157). pdf), Oganessian et al., JINR preprints, 2004. Retrieved on 3 March 2008[6] Oganessian, Yu. Ts.; Utyonkov, V.; Dmitriev, S.; Lobanov, Yu.; Itkis, M.; Polyakov, A.; Tsyganov, Yu.; Mezentsev, A. et al. (2005).

"Synthesis of elements 115 and 113 in the reaction 243Am + 48Ca". Physical Review C 72 (3): 034611. Bibcode 2005PhRvC..72c4611O.doi:10.1103/PhysRevC.72.034611.

[7] P. Roy Chowdhury, D. N. Basu and C. Samanta (2007). "α decay chains from element 113". Phys. Rev. C 75 (4): 047306.Bibcode 2007PhRvC..75d7306C. doi:10.1103/PhysRevC.75.047306.

[8] Barber, Robert C.; Karol, Paul J.; Nakahara, Hiromichi; Vardaci, Emanuele; Vogt, Erich W. (2011). "Discovery of the elements with atomicnumbers greater than or equal to 113 (IUPAC Technical Report)". Pure and Applied Chemistry: 1. doi:10.1351/PAC-REP-10-05-01.

[9] "RIKEN NEWS November 2004" (http:/ / www. riken. go. jp/ engn/ r-world/ info/ release/ news/ 2004/ nov/ index. html). . Retrieved 9February 2008.

[10] "Search for element 113" (http:/ / www. gsi. de/ informationen/ wti/ library/ scientificreport2003/ files/ 1. pdf), Hofmann et al., GSI report2003. Retrieved on 3 March 2008

[11] Oganessian et al.; Utyonkov, V.; Lobanov, Yu.; Abdullin, F.; Polyakov, A.; Sagaidak, R.; Shirokovsky, I.; Tsyganov, Yu. et al. (2007)."Synthesis of the isotope 282113 in the 237Np+48Ca fusion reaction" (http:/ / nrv. jinr. ru/ pdf_file/ PhysRevC_76_011601. pdf). Phys. Rev. C76: 011601(R). Bibcode 2007PhRvC..76a1601O. doi:10.1103/PhysRevC.76.011601. .

[12] Feng, Zhao-Qing; Jin, Gen-Ming; Li, Jun-Qing; Scheid, Werner (2007). "Formation of superheavy nuclei in cold fusion reactions". PhysicalReview C 76 (4): 044606. arXiv:0707.2588. Bibcode 2007PhRvC..76d4606F. doi:10.1103/PhysRevC.76.044606.

[13] Feng, Z; Jin, G; Li, J; Scheid, W (2009). "Production of heavy and superheavy nuclei in massive fusion reactions". Nuclear Physics A 816:33. arXiv:0803.1117. Bibcode 2009NuPhA.816...33F. doi:10.1016/j.nuclphysa.2008.11.003.

External links• WebElements.com: Ununtrium (http:/ / www. webelements. com/ ununtrium/ )• Uut and Uup Add Their Atomic Mass to Periodic Table (http:/ / www. radiochemistry. org/ periodictable/

elements/ 115. html)• Apsidium: Ununtrium 113 Uut (http:/ / web. archive. org/ web/ 20080615170757/ http:/ / www. apsidium. com/

elements/ 113. htm)• Discovery of Elements 113 and 115 (http:/ / www-cms. llnl. gov/ e113_115/ images. html)• Superheavy elements (http:/ / physicsweb. org/ articles/ world/ 17/ 7/ 7)

Article Sources and Contributors 83

Article Sources and ContributorsBoron group  Source: http://en.wikipedia.org/w/index.php?oldid=462894601  Contributors: 1297, AXRL, Abshahas, Ahoerstemeier, Alex43223, Alf.laylah.wa.laylah, Arindam5314034, Ary29,AxelBoldt, BlueEarth, Bob Saint Clar, Boothy443, Bowcek don, Bryan Derksen, CactusWriter, Chaosdruid, Chem-awb, Chitusinha, Choess, Chris Dybala, Closedmouth, Cntras,CommonsDelinker, DARTH SIDIOUS 2, DMacks, Donarreiskoffer, Dpvwia, Eddideigel, Edward, Emperorbma, Eras-mus, Eric119, Ericxpenner, Femto, Firq, Fonzy, Freakofnurture, FuturePerfect at Sunrise, Gamaliel, Gene Nygaard, Geo7777, Ground Zero, Gurkha711, Hadal, Hall Monitor, Headbomb, Hugo-cs, Hurricanehink, Icairns, Itub, Jimfbleak, Kam Solusar, Khazar, Koavf,Lanthanum-138, LilHelpa, Materialscientist, Mild Bill Hiccup, Mjp797, Mxn, Nergaal, Nirmos, Ochib, Odysseus1479, Ojs, Piplicus, R8R Gtrs, Rfc1394, Scerri, SchfiftyThree, Shell Kinney,Snoyes, Stone, Suriel1981, T. Anthony, Tarquin, Template namespace initialisation script, TheRanger, Tim Thomason, Titus III, Tmark111, Vrenator, Vsmith, Wikidenizen, XinaNicole, Yekrats,108 anonymous edits

Boron  Source: http://en.wikipedia.org/w/index.php?oldid=464640076  Contributors: 1Martin33, 28bytes, 2D, 8472, A876, Abradude, Ace of Spades IV, Acroterion, Adrian.benko, AkBigTrouble, Akldawgs, Alan012, Alanmarkrussell, Alansohn, Alchemist-hp, Alex43223, Alexeymorgunov, AlexiusHoratius, Andre Engels, Andres, Andrew Kanaber, Andrewlp1991, Antandrus,Anwar saadat, Appeltree1, Applekid, Archfiendweazal, Archimerged, Aristotle28, Arr0n456, Asiir, AtheWeatherman, Ausir, Aussie Alchemist, Avenged Eightfold, Avidallred, Avnjay, Avoided,BRG, Bagatelle, Bantman, Bart133, Barticus88, Bassbonerocks, Beetstra, Belromain, BenBurch, Bender235, Benjah-bmm27, Beyondthislife, BillFlis, Birdman1, Bkell, Black Falcon,Blackangel25, BlueDevil, Bobkeyes, Bomac, Boron1111, Brighterorange, Brockert, Bruinfan12, Bryan Derksen, Bryce, Bsauerwi, Bunny Angel13, C.A.T.S. CEO, CWii, CYD, Cacycle,Calabraxthis, CalicoCatLover, Calvin 1998, CanadianLinuxUser, Canley, CapitalR, Capricorn42, Captqrunch, CardinalDan, Carnildo, Cflm001, CharlesC, ChemNerd, Chemicalinterest,Chowbok, Chris Dybala, Chris the speller, Christian75, Chuunen Baka, Ciphergoth, Ckatz, Closedmouth, Condem, Conversion script, CopperKettle, Coppertwig, Corbon, Cosmium, Cramapple,Cuchullain, Cwkmail, Cybercobra, Cyrloc, DARTH SIDIOUS 2, DRTllbrg, DVD R W, DabMachine, Danski14, Darrien, Darth Panda, David Latapie, David notMD, DeadEyeArrow, Debresser,Deflective, Delldot, Delta G, DennyColt, DerHexer, Dhp1080, Die2u2, Diegusjaimes, Dino, Discospinster, Diwas, Dlae, Doctorfluffy, Dolovis, Doyleb23, Drilnoth, Dwmyers, Dycedarg,ESRFBeam, Ebe123, EdJohnston, Edcolins, Edgar181, Edsanville, Edward, El C, Elassint, Eldin raigmore, Elminster Aumar, Eltomzo, Emmyparker, Emperorbma, Epbr123, Eric119, ErikZachte, Escape Artist Swyer, Evand, Everard Proudfoot, FJPB, Facka, FaerieInGrey, Faradayplank, Farosdaughter, Femto, FengRail, Frank Warmerdam, Frankenpuppy, Freedomlinux,Frencheigh, Freysauce, Frymaster, Funeral, Funky Monkey, Fvw, GFZLab, Gamer6484, Gary Cziko, Gene Nygaard, Giftlite, Gilgamesh, Glenn, Gluckman, Gman124, Graham87, Grendelkhan,Gryphn, Gurps npc, Gyrobo, Hak-kâ-ngìn, Hans Dunkelberg, Hanswaarle, HappyM, HappyVR, Harland1, Haza-w, Hda3ku, Hdt83, Headbomb, Helixblue, HenryLi, Herbee, HexaChord,Hibernian, Hmrox, Hockeyplayer101, HowardJWilk, Icairns, Incompetence, Iridescent, Itub, Ixfd64, J.delanoy, JKeck, JRM, JV Smithy, James A. Stewart, JamesAM, Jan eissfeldt, Jaraalbe, JeffG., Jeronimo, Jetru, Jjeffrey, John, JohnCD, Jose77, Josh Parris, Joshlepaknpsa, Jossi, Jrockley, Justlettersandnumbers, Ka Faraq Gatri, Karl-Henner, Karlhahn, Katalaveno, Ke1v234, Keilana,KnowledgeOfSelf, Komojo, KonradG, Krellis, Ksbrown, Ktsquare, Kurykh, Kusunose, Kwamikagami, L'Aquatique, LA2, Lakmiseiru, LarryMorseDCOhio, Lauriemchorse, Lawrence Cohen,Lazulilasher, LeaveSleaves, Lec CRP1, LightAnkh, LikeLakers2, LilHelpa, LinaMishima, Ling.Nut, Lockesdonkey, Lon of Oakdale, LorenzoB, LtPowers, Luebuwei, LuigiManiac, Lxseto93,M.O.X, MER-C, MPerel, MZMcBride, Madmarigold, Majestik Moose, Mani1, Marcsin, Marie Poise, Marnanel, Master of Puppets, Materialscientist, Mav, Mayz, Mazca, McDogm, Mdf,Meaghan, Megaboz, Megan1967, Mgimpel, Mikemill, Mikespedia, Milkbreath, Minesweeper, Minnesota1, Miss Madeline, MisterSheik, Mongreilf, Movedgood, Mr0t1633, MrFish, Mufka,Mxn, Mygerardromance, NHRHS2010, Naaa127, Nakon, Nandita 115, Nantoz, Navnløs, NbmMudder, Nchaimov, Neillawrence, NerdyScienceDude, Nergaal, Netkinetic, Neutrality, NickNumber, Nickptar, Night Gyr, Nihiltres, Nik42, Nilmerg, Nk, Nono64, Noplasma, Numbo3, Ohnoitsjamie, Old Moonraker, Oliver Lineham, Olivier, Orca432, Oxymoron83, PDH, PStatic,Pabouk, Parker2334, PatVanHove, Paul from Michigan, Paul1953h, Pb30, Pe1er1, Pegasus1138, Pharaoh of the Wizards, Phgao, Philip Trueman, PierreAbbat, Pikna, Pinethicket, Pirkid, Pixel;-), Pixelface, Plantsurfer, PoliteCarbide, Polonium, Poolkris, Pretzelpaws, Pschemp, Pseudomonas, Psyche825, Puchiko, Pyrotec, Qmv3a99, Quadell, R'n'B, RJHall, RTC, Raeky, RaseaC,Rawling, Reach Out to the Truth, RedCoat10, RedWolf, Remember, Rememberway, RexNL, Reyk, Reza kalani, Riana, Rich Farmbrough, Richard Arthur Norton (1958- ), Richardb43, Richfife,Richnotts, Rifleman 82, Rjwilmsi, Rmashhadi, Robert Foley, Roberta F., Romanm, RoyBoy, Rplix, Rtcoles, Rursus, RyanJones, S9440996i, SEWilco, SH84, SMC, Salem 20078, Sallison,SamWhitey, Saperaud, Sbharris, Sbmehta, ScaldingHotSoup, Schneelocke, Scott Burley, Sengkang, Sfwilli, Shaddack, Shanes, Shirulashem, Sho Uemura, Shrew, Sietse Snel, Skarebo, SkyLined,Sl, Slowking Man, Slucas, Smokefoot, Snaxe920, Soliloquial, Solipsist, Solitude, Someone else, Squids and Chips, Ssbb1234, Staffwaterboy, Stassats, StephanieM, Stephenb, Steven Zhang,Steven69, Stone, StrontiumDogs, Stui, Stwalkerster, Suisui, Sunborn, Supercoop, Syncategoremata, Syrthiss, T40nsh1, THEN WHO WAS PHONE?, Tavilis, Tdjewell, Tempodivalse, Tetracube,The Thing That Should Not Be, The Toque, TheSeer, Theda, Thingg, Thricecube, Thumperward, Thyraxus, Tim Starling, Tiphareth, Tiptoety, Titoxd, Tlusťa, Tohd8BohaithuGh1, Tom harrison,Travis.Thurston, Trevor MacInnis, Trojancowboy, Trovatore, Ungvichian, Urhixidur, V7-sport, VASANTH S.N., Vcelloho, Vikingforties, Viriditas, Voyagerfan5761, Vsmith, Vssun, Walkerma,Walton One, Warut, Watch37264, Whitepaw, Whkoh, Wikiman7, Wikisaver62, William Avery, Wknight94, Woohookitty, Wyllium, Xiong Chiamiov, Yamamoto Ichiro, Yyy, Zach4636,Zelator, Zfr, Zotel, පසිඳු කාවින්ද, 1036 anonymous edits

Aluminium  Source: http://en.wikipedia.org/w/index.php?oldid=464532971  Contributors: (jarbarf), 000peter, 050555, 111112, 3.14159265358pi, 56, 842U, A Brave New World, A More Perfect Onion, A.C. Norman, A.Ou, A2Kafir, ABF, AOEU, Aazn, Aboctok, Abrech, Accurrent, Adambro, Adamd1008, Adashiel, Addshore, Adimovk5, AdjustShift, Aeluwas, Ahoerstemeier, Aiden Fisher, Aitias, Ajbxo, Akamad, Alanhidy, Alansohn, Alchemist-hp, Aldie, Ale jrb, Aleenf1, Alexey Feldgendler, Alexius08, Alexwcovington, AllGloryToTheHypnotoad, Allstarecho, Almazi, Alproffesor, Altenmann, Alumimum, American Eagle, Amgreen, Andesk, Andonic, Andrevan, Andyboza, Angela, Ann Stouter, Anonymous Dissident, AnotherBrian, Ansell, Antandrus, Antonio Lopez, Anwar saadat, Arakunem, Aranherunar, Archfalhwyl, Archimerged, ArielGold, Aristotle28, Ark2120, Army1987, Arnoutf, Artaxiad, Aruseusu, Arx Fortis, Asder smit, Askewchan, Aslonline, Astral, At the speed of light, Atlant, Audrius u, Avala, Average Earthman, Avicennasis, Avriette, AxSkov, AxelBoldt, BRUTE, Banes, Banpei, Bart Versieck, Basicdesign, Bast ailuros, Beetstra, Beland, BenFrantzDale, Bender235, Beni-Sakur-Six, Benjah-bmm27, Benjiboi, Bennetto, Benwildeboer, BigChicken, BigHairRef, Bihco, BillFlis, Billde, BillySharps, Bilsonius, Bjarki S, Bkell, Black Kite, Blainster, Blathnaid, Bleepbloopbloop, Bletch, Bobblewik, Bobo192, Boccobrock, Boffy b, Bomac, Bongwarrior, Boothy443, Bowlhover, Brandonlovesflasks, Brandonrush, Brian the Editor, Brian0918, Brianga, Bridesmill, Brighterorange, Brion VIBBER, Britzingen, Bryan Derksen, Bsadowski1, Bubba hotep, BuickCenturyDriver, BunnyFlying, Burgercat, Bücherwürmlein, C.Fred, C0nanPayne, CDThieme, CJ Madsen, CMILC, CWii, CYD, Cafzal, CalicoCatLover, Calmer Waters, Caltas, CambridgeBayWeather, Camden7, Camembert, Camw, Can't sleep, clown will eat me, Canadian Scouter, Canadian-Bacon, CanadianCaesar, CanadianLinuxUser, CanisRufus, Canthusus, CapitalLetterBeginning, Capricorn42, Captain panda, CaptainVindaloo, Carl Logan, Carldd11, Carnildo, Casliber, Casper2k3, Cassivs, Causesobad, Ccrrccrr, Celarnor, Centrx, Cfailde, Chameleon, Charles Gaudette, CharlotteWebb, Chasingsol, Chatt26, ChemNerd, Chemical Heritage, Chemicalinterest, Chemkid1, Chenzw, Chodges, Chris 73, Chrislk02, Chun-hian, Chzz, Cireshoe, Ckatz, Clark89, Closedmouth, Coasting, Cohesion, Cometstyles, CompIsMyRx, ConCompS, Conversion script, Corpx, CosineKitty, Coughinink, CrazyChemGuy, Cryptic C62, Curb Chain, Curps, Cybercobra, Cybergoonieenderwiggin, D, D. Recorder, D99figge, DMacks, DUBJAY04, DVD R W, DVdm, Dadude3320, Dark.Albatr0ss, Darklilac, Darkwraith, Darrien, DarthShrine, Davehi1, Daveisrategud, Davewild, David Latapie, David.Mestel, Dawn Bard, Dbachmann, Dbtfz, Dcljr, Dcoetzee, Ddurant, DeadEyeArrow, Debresser, Decltype, Deelkar, Deflective, Deglr6328, Deli nk, Delirium, Delldot, Delta G, Denni, Deor, DerHexer, Dforest, Dfrg.msc, Dhart, Diderot, Digeridouble, Dikteren, Dina, Discospinster, Dlohcierekim, Dmn, Dogsrockroll, Don4of4, Donarreiskoffer, Doovinator, Doseiai2, DoubleBlue, Doulos Christos, DrBob, DragonflySixtyseven, Drbreznjev, Dreadstar, Drmies, Drutt, Dtgriscom, Duckysmokton, Dududuh, Duh duh duh, Duke wellington 1815, Dwmyers, Dycedarg, DylanW, Dysprosia, EL Willy, Eadthem, Eagle99999, Eaolson, East718, EdBever, Eddyelm, Edgar181, Edison, El C, Elassint, Elektron, Element16, Eleuther, Eli the Bearded, Elkman, Emassey2005, EmilyBwater, Emperorbma, Enkauston, Enviroboy, Epbr123, Epo, Erebus555, Eric Kvaalen, Eric119, Erik Zachte, Esmehwp, Espoo, Eternal Pink, Evand, Everyking, Evil Monkey, Excirial, Exert, Extransit, Eyeguy3, Ezshay, Fabiform, Fahadsadah, Faithlessthewonderboy, Faradayplank, FastMarkets, Fattyjwoods, Favonian, Fayenatic london, Femto, FengRail, Ferkelparade, Ferret, Fg2, Fgdfgdfgsdfzg, Fieldday-sunday, Firebladed, FisherQueen, Fitzed, Florian Blaschke, Floul1, Flyers13, Flyguy649, FlyingToaster, Foobar, ForestAngel, Frankenpuppy, Franspinale, Fraser J Allison, Freakofnurture, Freedom fighter, Freestyle-69, Friginator, Futuraind, Fvasconcellos, GPHemsley, GW Simulations, Gaff, Gail, GainLine, Gaius Cornelius, GargoyleMT, Gary King, Gcsuchemistry, Gdo01, Gene Nygaard, Geni, Geniac, Gensanders, George The Dragon, GeorgeLouis, Georgec95, Georgewilliamherbert, Ghalas, Ghosts&empties, Giftlite, Gihanuk, Gilgamesh, Gilliam, Gillyweed, Gimcrackery, Giorgio51, Glenn, GlobeGores, Gnj, Gogo Dodo, GoldRingChip, GraemeL, Graham87, Great Cthulhu, GreatWhiteNortherner, Gregcaletta, Gregorian, Grendelkhan, Greyhood, Grim-Gym, Grmagne, Gtstricky, Gunde123456789, Gurch, Gurps npc, Gurubrahma, Gus Polly, Gwernol, Gyro199259, Gyrobo, Gzuckier, Gökhan, Ha Ha, king of Switzerland, Hadal, Hadcoforyou, Haeleth, Hairy Dude, Hak-kâ-ngìn, HalfShadow, Halvorseno, Hamiltondaniel, Hankwang, Hannah375, Harmil, Hartfree-Bright, Hawk512, Hdt83, Headbomb, Heartache95, Hello32020, Henrik, HenryLi, Herbee, HereToHelp, Heron, HexaChord, Hgrosser, Hidstar, Hoplophile, Hqb, Hraefen, Hu12, Huangcjz, Huangdi, Hut 8.5, Hydrogen Iodide, I80and, II MusLiM HyBRiD II, ITasteLikePaint, IW.HG, IWhisky, Icairns, Icek, Icepunisher, Igoldste, Ihcoyc, Ilurker, ImperfectlyInformed, Imroy, Inprov, InvertRect, Iridescent, Isis, Isopropyl, IstvanWolf, Iwanttodie, J.delanoy, J295, J4V4, JForget, JG17, JLaTondre, JNW, JaGa, Jaan513, Jaaronan, Jacek Kendysz, JackLumber, Jackol, Jadtnr1, Jadzianna, Jaganath, Jakestew@mail.com, James086, Jamesontai, JamieS93, Jan1nad, Janke, Jaraalbe, Jas9876, Jasen betts, Jason1956, Jauhienij, Java7837, Jay Litman, Jcwf, Jdforrester, Jeffjon, Jefflayman, Jeltz, Jennavecia, JeremyA, Jerry Seinfeld, Jespinos, JesseW, Jetman123, Jguk 2, Jiang, Jim77742, Jinian, Jinxed, Jj137, Jmah, John, JohnCD, Johnleemk, Jonathunder, Jooler, Joolz, Jorunn, Jose77, Joshschr, Joshthegreat, Josquius, Jowheelie, Joyous!, Jtdirl, Juanscott, Julesd, Juliancolton, Junglecat, Junip, Justforasecond, Jwray, KJBracey, KJS77, KPH2293, Kahuroa, Kalothira, Karn, Karthikganapathy, Katalaveno, Katieh5584, Kay Dekker, Kazvorpal, Kbh3rd, Kbogusz, Keenan Pepper, Keenman76, Keilana, Kelc07, Kember, Kevin B12, Kf4bdy, Kieff, King of Hearts, Kingkaos0, Kissoffire, Kku, KlaudiuMihaila, Klemen Kocjancic, Kmcanada, KnowledgeOfSelf, Koavf, Korandder, Kosebamse, KostasG, Kouban, Kowloonese, Kragen, Krun, Kukini, Kuru, Kurykh, Kwamikagami, Kyle Barbour, L33tminion, LAX, La Pianista, Lambiam, Lamro, Larspcus2, Lastyearswishes, Lazyguythewerewolf, Lazylaces, Lcawte, LeaveSleaves, Legend78, LeighvsOptimvsMaximvs, LemonSmints, Leujohn, Leyo, LiamE, Lightdarkness, Lightmouse, Lights, Ligulem, Litefantastic, Little Mountain 5, Livajo, Lo2u, Logan, LonelyMountain, Looper5920, Loren.wilton, LossIsNotMore, LouScheffer, LuigiManiac, Luk, Luke Sperduto, Lumos3, Luna Santin, Lunchscale, Lupin, M dorothy, MCGEEJES000, MER-C, MPerel, MZMcBride, Mac Davis, Mailer diablo, Mako098765, Malcolm Farmer, Malleus Fatuorum, Mandarax, Mani1, Marek69, Marj Tiefert, Mark Ryan, Martin451, Martinp23, Materialscientist, Mathemagician57721, Mathnerd314, Matthew Yeager, Mattrox90, Mav, Max SamuelC, MaxSem, Maxim Razin, Mbc362, Mbuguamuchoki, McSly, McTrixie, Mcpgv, MeMe213, Mee Merone, Megganonion, Meisterkoch, MementoVivere, Mephistophelian, Mercuryone, Metagraph, Metalxzxz, Mgimpel, Michaelas10, Miffyandfrends, Mike40033, Mikespedia, Mikiemike, Milesflint, Mimime, Mindmatrix, Minesweeper, Mintguy, Mirage GSM, Mirv, Miskaton, Miss Madeline, Mjpieters, Mkweise, Mmccrae, Moilleadóir, Mojosam, Monsoon Waves, Morehugh, Mpbx3003, Mpp piotrp, Mps, MrOllie, MrRadioGuy, Mrbrtk, Mschel, Mtelewicz, Muenda, Mulad, Mx3, Mxkjk2, Myanw, Mygerardromance, Mysekurity, Mythdon, N5iln, Nahat, Nakon, NawlinWiki, NeoVampTrunks, NeonGeniuses, Nepenthes, Nerd65536, Nergaal, Netkinetic, Nev1, NewEnglandYankee, Nick123, NickMartin, Nigosh, Nihiltres, Ninly, Nirvelli,

Article Sources and Contributors 84

Nishkid64, Nn123645, Nneonneo, Nohat, Noisy, Nokhc, Nono64, Normanton3, NorthernThunder, Not the duke of Devonshire, Novacatz, Nuance 4, NuclearWarfare, Nucleartape, Nucleusboy,Numbo3, Ocatecir, Oda Mari, Oknazevad, Oliver202, Olli Niemitalo, Omicronpersei8, Onorem, Onthegogo, Opelio, Orange Suede Sofa, Originalpimp, Otolemur crassicaudatus, OwenBlacker,OxMat, Oxymoron83, PFHLai, PGPirate, PJBEAR13, Pacholua234, Pakaran, Pandanx, Papaya07, Parkingtigers, Pascal.Tesson, Paterj41, Patstuart, Paul August, Paul from Michigan, PaulGS,PaulHallows, PaulHanson, Pavel Vozenilek, Pavlos vatavalis, Pax:Vobiscum, Pedro, Pedro12, PeepP, Pekinensis, Pepo13, PeregrineAY, Perique des Palottes, Persian Poet Gal, Personman, Pessi,Peter Ellis, Pethr, Pfahlstrom, Pgk, Pharaoh of the Wizards, Phe, Philip Trueman, Physchim62, Pi, Pi.1415926535, Pilotguy, Pinethicket, Pinkadelica, Piperh, Pit-yacker, Plastikspork, Plazak,Polyamorph, Polyparadigm, Pontificalibus, Poolkris, Poor Yorick, Porud!!!, Possum, Potato99, Prainog, Prari, Predecess, PrestonH, Primacag, Primalchaos, Primarscources, Proofreader77,Psi-kat, Psyche825, Ptdecker, Puchiko, Puffin, Purpleislost, Pyrochem, Quadell, Quantumelfmage, Quebec99, Quintote, Qwerty414, Qwfp, Qxz, RAM, RESURGAM, RJHall, RJaguar3, RTC,Rachel Pearce, Radon210, Raeky, Razimantv, Razorflame, Rcbleeds, Real Robbie, Reaper Eternal, Rebroad, Red Winged Duck, RedWolf, Reddi, Redux, Reedy, Remember, Remember the dot,Repairscircuitboards, Res2216firestar, Retired username, RevDan, RexNL, Reyk, Reywas92, Rfc1394, Riana, Rich Farmbrough, Richard001, Richardlw, Richnotts, Rifleman 82, Rintojiang,Rjwilmsi, Rkr1991, Rmky87, Roadrunner, RobertG, Robertvan1, Robin Patterson, Robuckmetal, RockMFR, Rohitbd, Romanm, Roni2204, Rory096, Rossnorman, Rsocol, Ryan Vesey,RyanJones, Ryancragg, Ryulong, S h i v a (Visnu), SDC, SHIMONSHA, Saddhiyama, Salamurai, Salmanazar, Sam Hocevar, Sam Korn, Sam Paris, SamDonner, Sampi, Sango123, Saperaud,Sbharris, Sbrownlee, Scarian, SchfiftyThree, Schneelocke, Schrodinger's cat is alive, Sciencewatcher, Scientizzle, Scream1013, Seb az86556, SemperBlotto, Sengkang, Seraphimblade,Serpent212, Sfahey, Sfgagnon, Shaddack, Shadowjams, Shans eW, ShaunMacPherson, Shirulashem, Shoefly, Shoessss, Shoy, Sigmund, Silentaria, Siliconov, Sillybilly, Silverbackmarlin,Silverfox1000, SimonP, Simply south, Sir Nicholas de Mimsy-Porpington, Sirbob592, Sjakkalle, Skatebiker, Sl, Sladen, Slakr, Slambo, Slinky puppet, Sloth monkey, Smartiger, Smithsterj,Smokefoot, Snek01, Snigbrook, Snowolf, Snoyes, SoM, SoWhy, Soccernjak, Sodium, Soliloquial, Solipsist, Some jerk on the Internet, Somedawgnamedjamie25, Someguy1221, Sometimessomethings, Soosed, Spa08cunninghams, Spaully, Spellmaster, Spencer, Spitfire, SpuriousQ, Squids and Chips, Sswan, StaticGull, Stephen G. Brown, Stephenb, Stereo, Stevenmitchell,Stifynsemons, Stismail, Stone, Storm Rider, Stormwriter, Strangerer, Streifenbeuteldachs, StuartH, Subash.chandran007, Suicidalhamster, Suisui, Sujan dey, Sunborn, Sundar, SusanLesch,SweatyJohnson, Sydbeqabarrett, Synesthesiac27, T. Anthony, T@nn, TICK TOCK, TVBZ28, Tabletop, Tagishsimon, Tangotango, Tapir Terrific, Tarquin, Tatery, Tbhotch, Tcncv,Technicaltechy, Tedickey, Tempodivalse, Terren5, Terrx, Tetracube, Tetrax994, Thaurisil, The Giant Puffin, The Next Doctor, The Noodle Incident, The Rambling Man, The Sunshine Man, TheThing That Should Not Be, The undertow, TheFeds, Thebigmansilver, Theda, Thedjatclubrock, Theone00, Theseeker4, Thingg, Thisisbossi, Thomas Milo, Thricecube, Thumperward,Thunderhead, Tiddly Tom, Tide rolls, Timeineurope, Timrollpickering, Timtrent, Titoxd, Tkynerd, Todan, Toddst1, Tom harrison, Tombomp, Tony Fox, Tony Sidaway, Tony1, TonyBallioni,Topbanana, Topsydog, Towerman86, Townmouse, TreasuryTag, Tregoweth, Trevor MacInnis, Triku, Trojancowboy, Trusilver, Tsogo3, Ttony21, Tumble, Turidoth, Turjan, Tuxlie, Tybreezy,Tyrol5, Tyugar, U.S.A.U.S.A.U.S.A., UberScienceNerd, Ubergeekguy, UkPaolo, Ukexpat, Ulric1313, Unflavoured, Unomi, Unregistered.coward, Useight, User A1, User86654, Utcursch, V----lSch----l, V8rik, VanHelsing, Vancouverguy, Vanderdecken, VanishedUser314159, Vcelloho, Vegaswikian, Velella, Vercalos, Versageek, Versus22, Vessels42, Viktor-viking, Vildricianus, Vina,Violetriga, Vortexrealm, VoteyDisciple, Vremya, Vrenator, Vsmith, Vssun, Vuo, Vuong Ngan Ha, Walkerma, Wanderson, Watch37264, Wavelength, Wayward, Wernher, Wiki alf, Wiki-Ed,Wikianon, Wikieditor06, Wikievil666, WikipedianMarlith, Wizard191, Wmahan, Wolfkeeper, WolfmanSF, Woohookitty, WookieInHeat, Work permit, Wronkiew, Wuhwuzdat, Wyllium, Wyss,X Constant X, XP1, Xam123456, Xannabellax, Xeworlebi, Xhaoz, Xiahou, Xp54321, Yamamoto Ichiro, Yansa, Yath, Yiplop stick stop, Yomom34, Yonatan, You knnow what, You knnow who,Youngjim, Yst, Ytrottier, Yurell, Yyy, ZX81, ZacBowling, Zach4636, Zamatech, Zarxos, Zigbigadoorlue, Zoe, Zoeb, Zomgadonggs, Zzuuzz, Zzyzx11, Zzzzziz, Ásgeir IV., Σ, 2579 anonymousedits

Gallium  Source: http://en.wikipedia.org/w/index.php?oldid=464562940  Contributors: 130.225.29.xxx, 28bytes, 2bias, 41523, 777sms, A. Carty, ABF, Abcfox, Achim1999, Adamhauner,Ahoerstemeier, Aitias, Alansohn, Alchemist-hp, AllanDeGroot, Altenmann, Andres, Annabel, Antandrus, Anyeverybody, Anypodetos, Archimerged, Ashley beauchamp, Auric, Avoided,AxelBoldt, B.d.mills, Bantman, Bdsmith, Beetstra, Benbest, Bennybp, Bggoldie, Bihco, BlueEarth, Bobo192, Boccobrock, Brandon5485, Brianski, Bryan Derksen, Butterscotch, CYD, CalveroJP, CanadianLinuxUser, CanisRufus, CapitalR, Capstone22, Capt. James T. Kirk, Captain538, Carnildo, Cekli829, Charitwo, Chelsea777, ChemNerd, ChicXulub, ChrisHodgesUK, Chrislk02,Coasthill, Cockneyite, Cometstyles, Conversion script, CryptoDerk, Curb Chain, Cybercobra, DLH, DMacks, DVD R W, Darrien, Darth Mike, David Latapie, DavidK93, Davidjonsson,DeadEyeArrow, Deasington, Deathring109, Deepu s, Deflective, Deglr6328, Delldot, Delta G, Deor, DerHexer, Derekvaiti, Dfrg.msc, Discospinster, Docboat, Dougie monty, Doulos Christos,DrBob, DragonflySixtyseven, Drahgo, Dysepsion, EPO, ESkog, EdC, Edgar181, El C, Element16, Emc2, Emperorbma, Epbr123, Eric119, Erik Zachte, Ewlyahoocom, Faceless Enemy, Facts707,Feline1, Femto, Fivemack, Flewis, Foobar, Fredrik, Fresheneesz, Frymaster, Fyver528, Fæ, Gaius Cornelius, Gallium31, Gauss, Gene Nygaard, George100, Georgyh, Gfad1, Giftlite, Gigemag76,Gjd001, Gman124, Gogo Dodo, Graham87, Grendelkhan, Gypsypkd, Gyrobo, Hadal, Hak-kâ-ngìn, HalfShadow, HappyInGeneral, Headbomb, Howabout1, HowardMorland, Hu, Hut 8.5,Hyenaste, IanOsgood, Icairns, Illuminatiscott, J.delanoy, Jaganath, Jaraalbe, Jerzy, Joanjoc, JoanneB, Joelholdsworth, John, Jose77, Kapricious81, Karlhahn, Kartano, Keegan, Keenman76,Khelben "Blackstaff" Arunsun, Kimera757, Kingpin13, Kiodane, Krich, Kwamikagami, LA2, Lachlancooper, Lesgles, Light current, Lolboy27, Lon of Oakdale, Lonewolf BC, Lord of the Pit,Loserdude, MZMcBride, Madhero88, Maelnuneb, Malcolm Farmer, Marcus1979, Mastermj72, Materialscientist, Matty4123, Mav, Mb5191, Mendaliv, Mgimpel, Michbich, Midoriko, Mike dill,MikeLynch, Mild Bill Hiccup, Minesweeper, Montrealais, Mr. Lefty, Mr.Z-man, Mr0t1633, Murkygrom, Mygerardromance, Naffer, Nagle, Nakon, NawlinWiki, Nedim Ardoğa, Neodymium60,Nergaal, NickCT, Nightscream, Nihil novi, Nihiltres, Ninjatacoshell, Nippoo, Nono64, Norm mit, Odie5533, Ohnoitsjamie, Opelio, OverlordQ, Palica, PandoraX, Pashute, Pearrari, Peligro,Phatom87, Philip Trueman, Pinethicket, Pip2andahalf, Plexust, Polyamorph, Ponyo, Poolkris, Poor Yorick, Pras, Prodego, R8R Gtrs, RTC, Ranveig, Rawling, Reflex Reaction, Remember,Retsnom 2, Reywas92, Rhobite, Riana, Rifleman 82, Rjwilmsi, Roberta F., Romanm, Rosiexdreamer, Rrburke, Ry49f83heiuovg9y43he, Saperaud, Sashalivesonforever, Sbharris, Schneelocke,Sengkang, Seraphim, Sfan00 IMG, Shad0, Shaddack, Shafei, ShaunMacPherson, Shawnlower, Sheitan, Shoemaker's Holiday, Siliconov, Sillybilly, Skatebiker, SkerHawx, Sketchmoose, Sl,Smithbrenon, Solar87, Splarka, Squids and Chips, Stifynsemons, Stone, Student7, Suisui, Sunborn, THEN WHO WAS PHONE?, Tagishsimon, Tarquin, Terrace4, Tetracube, The ObentoMusubi, The Thing That Should Not Be, The way, the truth, and the light, Theseeker4, Thibbs, Thricecube, Thumperward, Tiddly Tom, Tide rolls, Tim Starling, Tomaxer, Trojancowboy, Tyler,Tylerdmace, Ultramince, Van helsing, Vrenator, Vsmith, Vuo, Walkerma, Warut, Wfeidt, Wimt, Wjbeaty, Wknight94, Woelen, Wolfkeeper, Wtshymanski, Xeworlebi, Yekrats, Yyy, Zach4636,Zachwoo, Zaklikesmen, Zara1709, Zeborah, 590 anonymous edits

Indium  Source: http://en.wikipedia.org/w/index.php?oldid=463844764  Contributors: 3.14159265358pi, A Stop at Willoughby, A2Kafir, A8UDI, ABF, AXRL, Aadal, Access, AdjustShift,Ahoerstemeier, Alansohn, Anclation, Antandrus, Archimerged, Arkuat, Army1987, Arthana, AussieBoy, Avidallred, AxelBoldt, Baccyak4H, Bassplr19, Beetstra, Benbest, Bhny, BlueEarth,Bomac, Bovineone, Brandonsgaywiki, Brockert, Bryan Derksen, BryanC, CYD, Caltas, CalumH93, Carnildo, Chemicalinterest, Chris 73, Closedmouth, Conversion script, Cquan, Cybercobra,CyrilB, DAID, Daniel.barna, Darrien, David Latapie, Dbo789, Deflective, Delta G, Difluoroethene, DocWatson42, Download, Dschwen, Dvbyrne, Eaolson, Edgar181, Eeekster, El C,Emperorbma, Endymi0n, Enok Walker, Epbr123, Erik Zachte, Exor674, Facts707, Falcon8765, Feezo, Femto, Gaius Cornelius, Gasheadsteve, Gene Nygaard, Gobeirne, Gogo Dodo, GraemeBartlett, Grendelkhan, Gurps npc, Gyrobo, Hak-kâ-ngìn, Hannibal (usurped), Headbomb, Hebrides, Hede2000, Helge Skjeveland, Herbee, Heron, II MusLiM HyBRiD II, IP69.226.103.13,IW.HG, Icairns, Iceten, Imroy, J.delanoy, Jaan513, Jaraalbe, Jawed, Jeronimo, Jerryjackson42, Joanjoc, John, JohnCub, Jopusbob, Jose77, Julesd, Karenjc, Karl23, Karlhahn, Katalaveno,Kristinaknopp, Kwamikagami, Kyle1278, LA2, LallLallLall, Lanthanum-138, LarryMorseDCOhio, LcawteHuggle, Lidnariq, Loren.wilton, Mancunion, Materialscientist, Mav, Maximus Rex,Mdinger, Mdwh, Mgimpel, Michael Hardy, Michaelbusch, Midgley, Mikeblas, Mikespedia, Minesweeper, Miremare, Mm40, Momme, Moogwrench, Mortdefides, Muqman 52, NaBUru38,Nakon, NellieBly, Nergaal, Nihiltres, Nikevich, No Guru, NuclearWarfare, Nutiketaiel, Nweiheng, Oxymoron83, Paisa, Pengdehua2011, Picapica, PierceG, Piperh, Pixel ;-), Pko, Plantsurfer,PlatinumX, Plexust, Poolkris, Pras, Primoris, Pyrochem, R000t, R8R Gtrs, RTC, Reedy, Remember, Reyk, Reza kalani, Rich Farmbrough, Rickhdz, Rifleman 82, Rjwilmsi, Robert Fraser,Roberta F., Romanm, Saperaud, Sbharris, Schneelocke, Seeaxid, Sengkang, Sfuerst, ShaunMacPherson, SheepNotGoats, Shell Kinney, Sillybilly, Sl, Sloppy, Smack, Spitfire, Squids and Chips,Stephenb, Stifynsemons, Stone, Suisui, T.vanschaik, Tagishsimon, Tetracube, The Thing That Should Not Be, Thricecube, Thumperward, Traal, Trabert, Twinscimitars, Varlaam, Vrenator,Vsmith, Vuerqex, Warut, Wasbeer, Wiki alf, William Avery, Wizard191, Wolfkeeper, Worldburns, Yartamis, Yuckfoo, Yyy, Zamphuor, 307 anonymous edits

Thallium  Source: http://en.wikipedia.org/w/index.php?oldid=464115291  Contributors: 21655, 28421u2232nfenfcenc, Aarchiba, Achaemenes, AdjustShift, Aecis, Ageo020, Ahkond,Ahoerstemeier, Alchemist-hp, Alex.tan, Alvis, Andre Engels, Andros 1337, Antandrus, Arabani, Arcadian, Archimerged, Arkuat, Astanhope, Astatine-210, Barsoomian, Bayou Banjo, Bbartlog,Belg4mit, Bender235, Benjah-bmm27, Benjamin Mako Hill, Binky, Blah27, BlueEarth, Blueshirts, Borishal, Brockert, Brutaldeluxe, Bryan Derksen, CSWarren, CWii, CYD, Carnildo, Cburnett,Cecil, Cgingold, Ch'marr, Chasingsol, Chemicalinterest, Chris the speller, Christian75, Cmdr Scolan, Conversion script, Courcelles, Cwkmail, Cybercobra, DabMachine, Dajwilkinson, Darrien,Davemcarlson, David Haslam, David Latapie, Deflective, Delirium, Deutschgirl, Difluoroethene, Diwas, Doggie389, Donarreiskoffer, Dr Zak, DrBob, Dragonich777, Dschwen, Duja, Dysprosia,EagleFan, Edgar181, El C, Element16, Eleveneleven, Elfbunniegirl, Emperor, Emperorbma, Enok Walker, Eric119, Erik Zachte, Everyking, Excirial, Fabiform, Facts707, Feline1, Femto,Firedrop, FlyingPenguins, Froth, Fvasconcellos, GT5162, Gene Nygaard, Gilliam, Gnfnrf, Gogo Dodo, Graham87, GrahamHardy, Greatpatton, Greg Lindahl, Grendelkhan, Grumpyoldgeek,Gypsypkd, Gyrobo, Hak-kâ-ngìn, HappyCamper, HazyM, Headbomb, Hede2000, Helge Skjeveland, Hellbus, Hippietrail, Hofoen, Huji, Icairns, Ideyal, Itub, J.delanoy, JALockhart, Jacj,Jaelanrodriguez, Jaraalbe, Jd027, Jennyvu96, Jfromcanada, Jimbimedia, Joanjoc, Johantheghost, John, John Nevard, John of Reading, Josh, Josh Parris, Jsjxyz, KRSESQ, Karlhahn, Kcjenner,Kelisi, Kipholbeck, Kostmo, Ksaraf, Kurykh, Kwamikagami, Lamro, Liam Skoda, Lindmere, Linmhall, Liontooth, Lizzie Harrison, Looxix, LorenzoB, Lpnsm1, Lumos3, Madder, MalcolmFarmer, MapsMan, Marc Venot, Markjoseph125, Materialscientist, Mattfiller, Matthew0028, Mav, Mccready, Michael Snyder, MightyWarrior, Mikael Häggström, Minesweeper, Mortdefides,Mr Minchin, Mygerardromance, NReitzel, NT17, Nabokov, Namibnat, Neparis, Nergaal, Neverquick, Ngebendi, Nickkid5, Nihiltres, Niro5, Nuclearmedzors, Ojs, Oliverkroll, Omicronpersei8,Oobopshark, Orange Suede Sofa, Ortolan88, Oskar Wallströmer, OwenBlacker, Oxymoron83, Panthro, Paraballo, Petri Krohn, PhilHibbs, PigFlu Oink, PlatinumX, Poccil, Polonium, Poolkris,Prari, Proofreader77, Quadro, Quebec99, Qwfp, R8R Gtrs, RTC, Raghav273, Remember, Rjwilmsi, Roberta F., Romanm, Rossami, SHCGRA Max, Saperaud, Sbharris, Sbmehta, SchfiftyThree,Schneelocke, Scray, Sengkang, Seraphimblade, Sewebster, ShaunMacPherson, Sheitan, ShelfSkewed, Shinkolobwe, Shoessss, Shorvath, Shuipzv3, Sillybilly, Skatebiker, Sl, Smrgeog, Snezzy,Snori, Sokkor, SpLoT, Spitfire, Stemonitis, Stephen Hodge, Stephenpratt, SteveRamone, Stifynsemons, Stone, Suffusion of Yellow, Svante, TFOWR, Tagishsimon, Tetracube, The Anome,TheMoog, Thingg, Thumperward, Tiddly Tom, Tim Starling, Timtrent, Tomchiukc, Tpbradbury, Trovatore, TutterMouse, Twilsonb, UnicornTapestry, Uthbrian, VMoreira, Varlaam, Versus22,Vsmith, Warut, Watch37264, Welte, Wendy Wendy, Widefox, William Avery, Wpeer1, Wtmitchell, Wyklety, Xhmikos, YOSF0113, Yekrats, Yilloslime, Yyy, Zhou Yu, Zundark, 402anonymous edits

Ununtrium  Source: http://en.wikipedia.org/w/index.php?oldid=463355660  Contributors: Ahoerstemeier, Alfio, AlimanRuna, Allen3, Anoop.m, Attackman7171, Bender235, BlueEarth, Brett Dunbar, Bryan Derksen, Bubbha, Cacahueten, Carbuncle, CecilWard, Crystal whacker, Cybercobra, Daniel bg, Darrien, David Shay, Db099221, Deflective, Devleenasamanta, Difluoroethene, Dogposter, Doulos Christos, Drjezza, Edgar181, Emperorbma, Eric119, Feeeshboy, Femto, Ferengi, Finalius, Flying Jazz, Fonzy, Fukumoto, Fvw, Gveret Tered, Gyrobo, Harro5, Hashar,

Article Sources and Contributors 85

Headbomb, Hmrox, Hugo-cs, Icairns, Iwoelbern, Jar Lar, Jeltz, Joanjoc, John, KJS77, Kelovy, Kingdon, Kurykh, Kwamikagami, Leapmark, Liltibs, LizardJr8, Materialscientist, Mav, Mellery,Merovingian, Mikespedia, Nergaal, Netdragon, NewEnglandYankee, Nick Levine, Nihiltres, Nozzleman, Ortolan88, Pascal666, Plutoplanet, Polylerus, Poohbee13666, Poolkris, Pras, Quest forTruth, Rathlan, Reddi, Remember, Reyk, Rich Farmbrough, RickK, Rickjpelleg, Rifleman 82, Rjwilmsi, Roentgenium111, Romanskolduns, Rufty, Rufus843, Rursus, Saperaud, Schneelocke,ShaunMacPherson, Shimgray, SimonP, Siroxo, Skatebiker, Sl, Snoyes, Tagishsimon, Tetracube, The Anome, Timc, Trollminator, Vicki Rosenzweig, Vsmith, William Avery, Xoloz, Xtreambar,Zinc90, Zungsheungyu, 84 anonymous edits

Image Sources, Licenses and Contributors 86

Image Sources, Licenses and ContributorsFile:Boron mNACTEC.jpg  Source: http://en.wikipedia.org/w/index.php?title=File:Boron_mNACTEC.jpg  License: Creative Commons Attribution-Sharealike 3.0  Contributors: XvazquezFile:Aluminium-4.jpg  Source: http://en.wikipedia.org/w/index.php?title=File:Aluminium-4.jpg  License: Creative Commons Attribution 1.0 Generic  Contributors: unknownFile:Gallium crystals.jpg  Source: http://en.wikipedia.org/w/index.php?title=File:Gallium_crystals.jpg  License: GNU Free Documentation License  Contributors: Aiyizo, Billinghurst, Dbc334,Frumpy, Greatpatton, Mattes, Saperaud, Taxiarchos228, Túrelio, 3 anonymous editsImage:Indium wire.jpg  Source: http://en.wikipedia.org/w/index.php?title=File:Indium_wire.jpg  License: Creative Commons Attribution-ShareAlike 3.0 Unported  Contributors: User:DschwenFile:Thallium under argon atmosphere.jpg  Source: http://en.wikipedia.org/w/index.php?title=File:Thallium_under_argon_atmosphere.jpg  License: Creative Commons Attribution 1.0 Generic Contributors: JuriiFile:Borgruppe.jpg  Source: http://en.wikipedia.org/w/index.php?title=File:Borgruppe.jpg  License: GNU Free Documentation License  Contributors: de:User:Tomihahndorf.Image:B2O3powder.JPG  Source: http://en.wikipedia.org/w/index.php?title=File:B2O3powder.JPG  License: Creative Commons Attribution-Sharealike 3.0  Contributors: Materialscientist(talk). Original uploader was Materialscientist at en.wikipediaImage:Sphalerite2USGOV.jpg  Source: http://en.wikipedia.org/w/index.php?title=File:Sphalerite2USGOV.jpg  License: Public Domain  Contributors: Ra'ikeFile:Glasfaser Roving.jpg  Source: http://en.wikipedia.org/w/index.php?title=File:Glasfaser_Roving.jpg  License: GNU Free Documentation License  Contributors: NoiseD at de.wikipediaImage:Uv-LED.jpg  Source: http://en.wikipedia.org/w/index.php?title=File:Uv-LED.jpg  License: Attribution  Contributors: Denniss, Glenn, Saperaud, Severino666, 1 anonymous editsfile:Boron mNACTEC.jpg  Source: http://en.wikipedia.org/w/index.php?title=File:Boron_mNACTEC.jpg  License: Creative Commons Attribution-Sharealike 3.0  Contributors: XvazquezFile:Loudspeaker.svg  Source: http://en.wikipedia.org/w/index.php?title=File:Loudspeaker.svg  License: Public Domain  Contributors: Bayo, Gmaxwell, Husky, Iamunknown, Mirithing,Myself488, Nethac DIU, Omegatron, Rocket000, The Evil IP address, Wouterhagens, 16 anonymous editsFile:Sassolite.jpg  Source: http://en.wikipedia.org/w/index.php?title=File:Sassolite.jpg  License: Public domain  Contributors: Aram Dulyan (User:Aramgutang)File:Bor 1.jpg  Source: http://en.wikipedia.org/w/index.php?title=File:Bor_1.jpg  License: Creative Commons Attribution-Sharealike 2.0  Contributors: Alchemist-hp, MaksimFile:Tetraborate-xtal-3D-balls.png  Source: http://en.wikipedia.org/w/index.php?title=File:Tetraborate-xtal-3D-balls.png  License: Public Domain  Contributors: Ben MillsFile:Boron-trifluoride-pi-bonding-2D.png  Source: http://en.wikipedia.org/w/index.php?title=File:Boron-trifluoride-pi-bonding-2D.png  License: Public Domain  Contributors: Ben MillsFile:Magnesium-diboride-3D-balls.png  Source: http://en.wikipedia.org/w/index.php?title=File:Magnesium-diboride-3D-balls.png  License: Public Domain  Contributors: Ben MillsFile:Neutroncrosssectionboron.png  Source: http://en.wikipedia.org/w/index.php?title=File:Neutroncrosssectionboron.png  License: Public Domain  Contributors: wikipedia:en:user:CadmiumFile:ulexita br.jpg  Source: http://en.wikipedia.org/w/index.php?title=File:Ulexita_br.jpg  License: Public Domain  Contributors: Andresboni, Ra'ikeFile:Borax crystals.jpg  Source: http://en.wikipedia.org/w/index.php?title=File:Borax_crystals.jpg  License: Public domain  Contributors: Aram Dulyan (User:Aramgutang)File:Schott Duran glassware.jpg  Source: http://en.wikipedia.org/w/index.php?title=File:Schott_Duran_glassware.jpg  License: Public Domain  Contributors: Original uploader was Skatebikerat en.wikipediaFile:Bodyarmor.jpg  Source: http://en.wikipedia.org/w/index.php?title=File:Bodyarmor.jpg  License: Public Domain  Contributors: Jwissick, 3 anonymous editsFile:Navy emergency flare.jpg  Source: http://en.wikipedia.org/w/index.php?title=File:Navy_emergency_flare.jpg  License: Creative Commons Attribution-ShareAlike 3.0 Unported Contributors: Krzysztof Burghardtfile:Aluminium-4.jpg  Source: http://en.wikipedia.org/w/index.php?title=File:Aluminium-4.jpg  License: Creative Commons Attribution 1.0 Generic  Contributors: unknownfile:Aluminum Spectra.jpg  Source: http://en.wikipedia.org/w/index.php?title=File:Aluminum_Spectra.jpg  License: Public Domain  Contributors: (teravolt (talk)). Original uploader wasTeravolt at en.wikipediaImage:Speakerlink.svg  Source: http://en.wikipedia.org/w/index.php?title=File:Speakerlink.svg  License: Creative Commons Attribution 3.0  Contributors: Woodstone. Original uploader wasWoodstone at en.wikipediaFile:Aluminium bar surface etched.jpg  Source: http://en.wikipedia.org/w/index.php?title=File:Aluminium_bar_surface_etched.jpg  License: Free Art License  Contributors: Alchemist-hp(talk) ( www.pse-mendelejew.de)File:Bauxite hérault.JPG  Source: http://en.wikipedia.org/w/index.php?title=File:Bauxite_hérault.JPG  License: Creative Commons Attribution-ShareAlike 1.0 Generic  Contributors: saphonFile:Aluminium - world production trend.svg  Source: http://en.wikipedia.org/w/index.php?title=File:Aluminium_-_world_production_trend.svg  License: Public Domain  Contributors: LeyoFile:Aluminium output2.PNG  Source: http://en.wikipedia.org/w/index.php?title=File:Aluminium_output2.PNG  License: Creative Commons Attribution-Sharealike 3.0  Contributors:User:Anwar_saadat/bubble_maps_(FAQ)File:41 ALU Recycling Code.svg  Source: http://en.wikipedia.org/w/index.php?title=File:41_ALU_Recycling_Code.svg  License: GNU Free Documentation License  Contributors: Karl ARandall / User:k4rlRFile:Trimethylaluminium-3D-balls.png  Source: http://en.wikipedia.org/w/index.php?title=File:Trimethylaluminium-3D-balls.png  License: Public Domain  Contributors: Benjah-bmm27,EphemeroniumFile:aluminumfoil.jpg  Source: http://en.wikipedia.org/w/index.php?title=File:Aluminumfoil.jpg  License: Public Domain  Contributors: Kerkyra, 2 anonymous editsFile:Austin A40 Roadster ca 1951.jpg  Source: http://en.wikipedia.org/w/index.php?title=File:Austin_A40_Roadster_ca_1951.jpg  License: Creative Commons Attribution-Sharealike3.0,2.5,2.0,1.0  Contributors: Charles01File:AluminumSlab.JPG  Source: http://en.wikipedia.org/w/index.php?title=File:AluminumSlab.JPG  License: Public Domain  Contributors: ALIquotobFile:Aluminium foam.jpg  Source: http://en.wikipedia.org/w/index.php?title=File:Aluminium_foam.jpg  License: Creative Commons Attribution 3.0  Contributors: StehfunFile:Eros-piccadilly-circus.jpg  Source: http://en.wikipedia.org/w/index.php?title=File:Eros-piccadilly-circus.jpg  License: GNU Free Documentation License  Contributors: Bhoeble, DorukSalancı, G.dallorto, Gerardus, Hanzo86, Jastrow, Joanjoc, Justinc, Korrigan, Montrealais, Pseudomoi, Saperaud, Simonxag, Wst, Xenophon, 4 anonymous editsfile:Gallium1 640x480.jpg  Source: http://en.wikipedia.org/w/index.php?title=File:Gallium1_640x480.jpg  License: unknown  Contributors: -File:Gallium kristallisiert.JPG  Source: http://en.wikipedia.org/w/index.php?title=File:Gallium_kristallisiert.JPG  License: Creative Commons Attribution-Sharealike 3.0  Contributors: Tmv23& DblayFile:Blue LED and Reflection.jpg  Source: http://en.wikipedia.org/w/index.php?title=File:Blue_LED_and_Reflection.jpg  License: GNU Free Documentation License  Contributors:Alexofdodd at en.wikipediaImage:Equilibrium.svg  Source: http://en.wikipedia.org/w/index.php?title=File:Equilibrium.svg  License: Public Domain  Contributors: L'Aquatiquefile:Indium.jpg  Source: http://en.wikipedia.org/w/index.php?title=File:Indium.jpg  License: Creative Commons Attribution-Sharealike 3.0  Contributors: NerdtalkerImage:Indium wetting glass.jpg  Source: http://en.wikipedia.org/w/index.php?title=File:Indium_wetting_glass.jpg  License: Public Domain  Contributors: SchtoneImage:S-process-elem-Ag-to-Sb.svg  Source: http://en.wikipedia.org/w/index.php?title=File:S-process-elem-Ag-to-Sb.svg  License: GNU Free Documentation License  Contributors: LionelAllorge, Pieter Kuiper, Rursus, 1 anonymous editsImage:Dell axim LCD under microscope.jpg  Source: http://en.wikipedia.org/w/index.php?title=File:Dell_axim_LCD_under_microscope.jpg  License: GNU Free Documentation License Contributors: 2 anonymous editsfile:Thallium pieces in ampoule.jpg  Source: http://en.wikipedia.org/w/index.php?title=File:Thallium_pieces_in_ampoule.jpg  License: Creative Commons Attribution-Sharealike 3.0 Contributors: W. OelenFile:Hutchinsonite-131710.jpg  Source: http://en.wikipedia.org/w/index.php?title=File:Hutchinsonite-131710.jpg  License: unknown  Contributors: -File:Thallium rod corroded.jpg  Source: http://en.wikipedia.org/w/index.php?title=File:Thallium_rod_corroded.jpg  License: Creative Commons Attribution-ShareAlike 3.0 Unported Contributors: User:DschwenFile:Skull and crossbones.svg  Source: http://en.wikipedia.org/w/index.php?title=File:Skull_and_crossbones.svg  License: Public Domain  Contributors: unknown

License 87

LicenseCreative Commons Attribution-Share Alike 3.0 Unported//creativecommons.org/licenses/by-sa/3.0/