8TH GROUPElements of

Elements of Group 8

Iron ( Fe ) Hassium ( Hs )

Osmonium (Os)

Ruthenium (Ru)

IRON (FE)

Introduction

Iron is a lustrous, ductile, malleable, silver-gray metal (group VIII of the periodic table). It is known to exist in four distinct crystalline forms. Iron rusts in damp air, but not in dry air. It dissolves readily in dilute acids. Iron is chemically active and forms two major series of chemical compounds, the bivalent iron (II), or ferrous, compounds and the trivalent iron (III), or ferric, compounds.

PHYSICAL PROPERTIES

Atomic Number 26

Atomic Weight 55.845

Melting Point 1811 K (1538°C or 2800°F)

Boiling Point 3134 K (2861°C or 5182°F)

Density 7.874 grams per cubic centimeter

Phase at Room Temperature Solid

Element Classification Metal

Period Number 4

Group Number     8

Group Name none

Uses

In addition to helping build the world around us, iron helps keep plants and animals alive. Iron plays a role in the creation of chlorophyll in plants and is an essential part of hemoglobin, the substance that carries oxygen within red blood cells. Iron sulfate (FeSO4) is used to treat the blood disease anemia.

Ordinary carbon steel is an alloy of iron with carbon (from 0.1% for mild steel up to 2% for high carbon steels), with small amounts of other elements. Alloy steels are carbon steels with other additives such as nickel and chromium. Non-corroding stainless steel contains high levels of chromium and nickel.

Dangerous

Iron (III)-O-arsenite, pentahydrate may be hazardous to the environment; special attention should be given to plants, air and water. It is strongly advised not to let the chemical enter into the environment because it persists in the environment.

Reaction

Iron does not clearly alter in pure water or in dry air, but when both water and oxygen are present (moist air), iron corrodes. Its silvery colour changes to a reddish-brown, because hydrated oxides are formed. Dissolved electrolytes accelerate the reaction mechanism, which is as follows:

4Fe + 3O2 + 6H2O 4Fe3+ + 12OH- 4Fe(OH)3 or 4FeO(OH) + 4 H2O

HASSIUM (HS)

Hassium is a chemical element with symbol Hs and atomic number 108, named after the German state of Hesse. It is a syntetic element (an element that can be created in a laboratory but is not found in nature) and rradioactive; the most stable known isotope, 269Hs, has a half-life of approximately 9.7 seconds, although an unconfirmed metastable state, 277Hs, may have a longer half-life of about 11 minutes. More than 100 atoms of hassium have been synthesized to date.

Physical Properties

Atomic Number 108

Atomic Weight 270

Melting Point Unknown

Boiling Point Unknown

Density Unknown

Phase at Room Temperature Solid

Element Classification Metal

Period Number 7

Group Number 8 

Group Name non

Uses

At present, it is only used in research.

Reaction

In 2004, scientists announced that they had succeeded in carrying out the first acid-base reaction with a hassium compound, forming sodium hassate(VIII):

HsO4 + 2NaOH → Na2[HsO4(OH)]

RUTHENIUM (RU)

Ruthenium, together with rhodium, palladium, osmium, iridium, and platinum form a group of elements referred to as the platinum group metals (PGM).

Ruthenium is a hard, white metal. It does not tarnish at room temperatures, but oxidises in air at about 800°C. The metal is not attacked by hot or cold acids or aqua regia, but when potassium chlorate is added to the solution, it oxidises explosively. It dissolved in molten alkalis.

Physical properties

Atomic number 44

Atomic mass 101.1 g.mol -1

Electronegativity according to Pauling 2.2

Density 12.2 g.cm-3 at 20°C

Melting point 2250 °C

Boiling point 4150 °C

Vanderwaals radius 0.135 nm

Isotopes 11

Electronic shell [ Kr ] 4d7 5s1

Energy of first ionisation 722.4 kJ.mol -1

Energy of second ionisation 1620 kJ.mol -1

Energy of third ionisation 2747 kJ.mol -1

Standard Potential 0.45 V

Discovered by Karl Klaus in 1844

Reactions

Reaction with air

Ru(s) + O2(g)RuO2(s)

Reaction with halogen

Ru(s) + 3F2(g)RuF6(s)

Applications In electronics , it used to be used mainly for electrical contacts but

most now goes into chip resistors.

In the chemical industry it is used in the anodes for chlorine production in electrochemical cells.

The metal is used as a hardener for palladium and platinum and added in small amounts improves the corrosion resistance of titaniumin.

It is used in electrical contact alloys and filaments, in jewelry, in pen nibs, and in instrument pivots. It is also used in alloys with cobalt, molybdenum, nickel, tungsten, and other metals.

Color ceramics and glass. 

instance in the removal of H2S from oil refineries and from other industrial processes

production of ammonia from natural gas,

production of acetic acid from methanol.

absorb light throughout the visible spectrum and are being actively researched in various, potential, solar energy technologies.

Ruthenium in Environment

Ruthenium is one of the rarest metals on Earth.

Ruthenium is found as the free metal, sometimes associated with platinum, osmium and iridium, in North and South America and in South Africa. There are few minerals, such as laurite, ruarsite and ruthenarsenite. All are rare and none acts as a commercial source of the metal. Ruthenium is also associated with nickel and deposits (from which it is recovered commercially). World production is 12 tonnes per year and reserves are hestimated to be ariund 5.000 tonnes.

Effects

Health effects of ruthenium Stain the skin very strongly. It

seems that ingested ruthenium is retained strongly in bones. Ruthenium oxide, RuO4, is highly toxic and volatile, and to be avoided.

Rhutenium 106 is one of the radionuclides involved in atmospheric testing of nuclear weapons, which began in 1945, with a US test, and ended in 1980 with a Chinese test. It is among the long-lived radionuclides that have produced and will continue to produce increased cancers risk for decades and centuries to come.

Environmental effects of ruthenium

Very few data are available on ruthenium impact on plants and estimates of its uptake have deducted levels of 5 ppb or less, although algae appear to concentrate it. No negative environmental effects have been reported.

OSMONIUM (OS)

Introduction

Osmium discovered by Smithson Tennant in 1803. The name is derived from the Greek word 'osme', meaning smell. Osmium is a rare, lustrous, very hard, brittle, bluish-white metal. It is the densest of all the elements. Osmium is uneffected by water and acids, but dissolves with molten alkalis. Osmium powder reacts slowly with the oxygen of the air and gives off detacteble amounts of osmium tetroxide vapour.

Physical properties

Reactions

Reaction of osmium with air

in air, finely divided osmium metal gives off a characteristic smell of OsO4 - bad news given that OsO4 is highly toxic.

Os(s) + 2O2(g) → OsO4(s)

Reaction of osmium with the halogens

Osmium reacts with either chlorine, Cl2, or bromine, Br2, with heating under pressure to form the tetrahalides osmium(IV) chloride, OsCl4, or osmium (IV) bromide, OsBr4.

Os(s) + 2Cl2(g) → OsCl4(s) (red)

Os(s) + 2Br2(l) → OsBr4(s) (black)

Osmium is principally used alloyed with other metals in the platinum group to produce very hard alloys. An alloy of 90% platinum and 10% osmium is used in surgical implants such as pacemakers and replacement heart valves. Osmium tetroxide is used in microscopy as a stain for fatty tissue and in fingerprint detection.

Health effects of osmium

Osmium tetroxide, OsO4, is highly toxic. Concentrations in air as low as 10-7 gm-3 can cause lung congestion, skin damage, and severe eye damage.

THE END