Unit 4: The Periodic Table and Periodicity
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Transcript of Unit 4: The Periodic Table and Periodicity
Unit 4: The Periodic Tableand Periodicity
Chemistry
OutlineOutline
The Elements
elements known to the ancients…
Element names come from a variety of sources.
place names…
famous people…
foreign languages…
mythology-related names…
names related to element properties…
S, Cu C, Sn,
Fr, Po, Ge, Eu, Am, Cf, Sc
Es, Md, No, Rf, Bh
Hg
TiTh,
W, Fe, Au, Ag, Pb, Cu
atomic number
Background on the Periodic Table
Dmitri Mendeleev: given creditfor Periodic Table (~1870)
--
--
organized Table byincreasing atomic mass left spaces and predictedproperties of undiscoveredelements
Henry Moseley: put elements inorder of increasing____________.
Mendeleev
Moseley
Describing the Periodic Table
periodic law: the properties of elements repeat every so often
period:
group (family):
horizontal row; there are 7
vertical column; there are 18 18
1716151413
129 10 1187654
1
3
21
2
34
6
7
5
Regions of the Table
metals: left side of Table; form cations
properties:
lustrous(shiny)
ductile(can pullinto wire)
malleable(can hammerinto shape)
good conductors(heat and electricity)
nonmetals: right side of Table; form anions
properties: good insulatorsgases or brittle solids
Regions of the Table (cont.)
Br2I2S8Ne
bromineiodinesulfurneon
computer chips
metalloids (semimetals): “stair” between metalsand nonmetals
properties: in-between those of metalsand nonmetals; “semiconductors”
Regions of the Table (cont.)
(B, Si, Ge, As, Sb, Te, Po)
Si and Ge
computer chips
metals
nonmetals
alkali metals:
alkaline earth metals:
halogens:
noble gases:
contain f orbitals
lanthanides:
coinage metals:
transition elements:main block (representative) elements:
group 1 (except H); 1+ charge;very reactive
group 2; 2+ charge;less reactive than
alkalisgroup 17; 1– charge; very reactive
group 18; no charge; unreactive
elements 58–71
actinides: elements 90–103
group 11 (part of the transition metals)
groups 3–12; variable charges; d block
groups 1, 2, 13–18; s and p block
alkaline earth metals
halogensnoble gaseslanthanides
alkali metals
actinides
coinage metals (part of the transition metals)
transition elements
main block elementsmetalloids
hydrogenmore nonmetals
more metals
Honors
• Trans-uranic Elements• Elements with an atomic number greater than 92.
www.chemicool.com
• Complete data table as a group of two, defend your decision using the form. You may write your defense in essay form if needed. Be specific and answer all guiding questions.
• Due next Wednesday, Jan. 15, 2014
Einsteinium (Es)
Albert Einstein– Relativity– E = mc2
– Offered Presidency of Israel– Element 99– Photoelectric effect
• Solar calculator
Curium (Cm)
• Madame Curie– Pioneer in radioactivity
• (Ra = radium)– 25 pounds of pitchblende ore
yields 1/1000 of a gram of radium– Emits 2 millions times as much
radiation as uranium
• (Rn = radon gas)
– Discovered 5 elements– Nobel Prize (5 in Curie family)
– Born in Poland • (Po = polonium)
Marie Curie (1876–1934)
Radium (Ra)
Radium was used as a fluorescent paint on watch dials. It wasapplied with thin brushes that workers would lick to keep a fine tip. Many people died from the exposure to radium.
Radon Gas
Radon gas occurs naturallyfrom the radioactive decayof radium. Radium is found in small amounts in rock.
Ra Rn + radiation
Predicted fraction of homes over 4 picocuries/liter radon
Zone 1 counties have a predicted average indoor radon screening level greater than 4 pCi/L (pico curies per liter) (red zones)
Zone 2 counties have a predicted average indoor radon screening level between 2 and 4 pCi/L (orange zones)
Zone 3 counties have a predicted average indoor radon screening level less than 2 pCi/L (yellow zones)
http://www.epa.gov/radon/zonemap.html
Nobelium (No)Element 102
Alfred Nobel
Nobel PrizeInventor: dynamite (TNT) blasting gelatin
“Merchant of Death”
CH3
NO2
NO2O2N
Trinitrotoluene
Seaborgium (Sg)
Glenn Seaborg– Separated f-block from rest of periodic table– Worked on Manhattan Project
(Atomic bomb)– Classified until after WW II– Element 106
• Only living person to have an element named for them
Silicon vs. Silicone
• Silicon (Si) element• Silicone (…Si – O – Si…) polymer
– Sealant (caulk) prevents leaks
– Breast augmentation
No cause-and-effect relationship exists between breast enlargement and breast cancer. Only oneresearcher found a causal link.
Magnesium
Atomic Mass 24 amumelting point = 650oC (1202oF)
silver gray metal
used in flash bulbs, bombs,and flares8th most abundant element (2.2% of Earth’s crust)
lack of Mg produces same biological effect as alcoholism (delirium tremens)
Mg24.305
12
Mendeleev’s Work!
• http://www.screencast.com/t/kg5WRCqrqcUh
Periodicity
The quality of being periodic; tendency to recur at regular intervals.
Electro negativity
Tendency of an atom to attract electrons towards itself.
Same number of valence e– =
Li Na
In any group, the element BELOW has one moreoccupied energy level than does the element ABOVE.
Li Na
similar properties
1s2 2s1 1s2 2s2 2p6 3s1
The period that an element is in is the same as theenergy level that its valence electrons are in.
Li Na
v.e– in 2nd E.L. v.e– in 3rd E.L.
in 3rd periodin 2nd period
Periodicity
there are trends in properties of elements
-- left-right AND up-down trends
atomic radius: the size of a neutral atom
add a new energylevel each time
WHY?
…increases as we go
…decreases as we go
WHY?
coulombic attraction: attraction between (+) and (–)
it has to do with…
Coulombic attraction depends on…
2– 2+
2+ 2– 1–
2–
1+
2+
amount of charge distance between charges
+ + – –
H
He
+ –
+ – + –
As we go , more coulombic
attraction, no new energy level, more pull, smaller size
shielding effect: kernel e– “shield” valence e–
from attractive force of the nucleus
Li v.e–
K v.e–
-- caused by kernel and valence e–
repelling each other
As we go , shielding effect increases.
tougher to remove
easierto remove
ionic radius:
cations anions
Ca atom Ca2+ ion Cl atom Cl1– ion
the size of an ion
20 p+
20 e–
20 p+
18 e–
17 p+
17 e–
17 p+
18 e–
Ca Ca2+ Cl Cl1–
cations are smaller anions are larger
ionization energy: the energy required to remove an e– from an atom
M + 1st I.E.
M + 2nd I.E.
M + 3rd I.E.
As we go , 1st I.E….
As we go , 1st I.E….
M1+ + e–
M2+ + e–
M3+ + e–
removes 1st e–
Each successive ionization requiresmore energy than the previous one.
decreases.
increases.
(due to the shielding effect)
electronegativity:
Linus Pauling quantifiedthe electronegativity scale.
the tendency fora bonded atom toattract e– to itself
As we go , electronegativity…
As we go , electronegativity…
decreases.
increases.
electronegativity increases
Summary of Summary of Periodic TrendsPeriodic Trends