Elements
Group 16 Elements
{
{
The Chalcogens
{
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All group elements are
solids except oxygen
oxygen, sulfur, and
selenium = nonmetals
tellurium = metalloid
polonium = metal
Amanda Runge
Meghan Estochen
Mark Humberstone
Physical Properties
OXYGEN
Selected Properties
Covalent radius/pm
O
S
Se
Te
Po
74
104
117
137
140
Ionic radius/pm
140
184
198
221
First Ionization
energy (kJ/mol)
1310
1000
941
870
812
Melting point/ºC
-218
113
217
450
254
Boiling point/ºC
-183
445
685
990
960
3.5
2.5
2.4
2.1
2
141
200
195
190
183
Pauling
Electronegative
Electron Affinity
(kJ/mol)
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OXYGEN
{
{
OXYGEN
Oxygen, the most abundant element
of the group, is found as two
allotropes, dioxygen (O2) and ozone
(O3).
Dioxygen‘s ground state is triplet
oxygen as well as a state of higher
energy, singlet oxygen.
Triplet
State
OXYGEN
{
{
{
{
{
Electrons and charged particles
that are given off by the sun
can hit triplet state oxygen,
exciting it into the singlet state.
When the electron falls back to
the ground state, visible light is
emitted, producing the Aurora
Borealis.
Colors seen are determined by
the altitude and energy at
which the collisions between
particles and electrons are
taking place
Particles = 1000 – 15000 eV
Occurs at poles because
charged particles are channeled
by Earth’s magnetic
field lines which go
into the poles
Singlet
State
OXYGEN
{
{
It is the second most electronegative
element in periodic table, making it
the most reactive of the group.
The high electronegativity of oxygen
leads to polarity in bonding.
z
{
i.e. Hydrogen-Bonding in water
The oxidation state of oxygen is -2.
The lack of d-orbitals makes it
difficult for higher states.
2
SULFUR
SULFUR
{
{
Sulfur is commonly found as an
8-membered ring. Poor pi-orbital
overlap due to larger atomic size
hinders double bonding with itself.
It can form stable compounds with
oxidation states ranging between
-2 and +6. Its most common states
are -2, +4, and +6. This is due to
the availability of d-orbitals.
SULFUR
{
Sulfur forms a similar structure with
hydrogen as it does with oxygen,
but the differences in
electronegativity make H2S less
polar and therefore less likely to
hydrogen bond.
SULFUR
{
{
{
Sulfur was the basis for mustard gas, a
cancer causing weapon used in
World War I.
By changing the structure of the gas and
substituting nitrogen for sulfur,
N-mustard is used to fight Hodgkin’s
Disease and many types of cancer.
Sulfur is also a component found in stink
bombs usually in the form of H2S.
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Mustard Gas
{
{
{
SULFUR
SELENIUM & TELLURIUM
N-mustard
Sulfur was the basis for mustard gas, a
cancer causing weapon used in
World War I.
By changing the structure of the gas and
substituting nitrogen for sulfur,
N-mustard is used to fight Hodgkin’s
Disease and many types of cancer.
Sulfur is also a component found in stink
bombs usually in the form of H2S.
SELENIUM & TELLURIUM
{
{
{
Selenium and tellurium are both large
metalloids with similar properties.
They exhibit oxidation states similar to
sulfur that also range from -2 to +6.
Their commonly found structures are
different. Selenium is found as an
8-membered ring (like sulfur) and
tellurium crystallizes in a chain-like form.
SELENIUM & TELLURIUM
{
{
Selenium and tellurium combine
with most elements although not as
readily as the more electronegative
members of the group, oxygen and
sulfur.
Selenium exhibits both photovoltaic
and photoconductive actions and
therefore is used in the production
of photocells and solar cells.
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POLONIUM
POLONIUM
{
{
Polonium, a radioactive element, is
rarely found in nature. It’s made in
small quantities by a nuclear
reaction with bismuth.
There are 29 known radioisotopes
and more known isotopes than any
other element.
209
83
POLONIUM
{
{
{
Polonium crystallizes in a cubic
structure.
Due to large atomic size, Pi orbital
overlap becomes difficult, therefore
rarely forms double bonds.
Following the trend, it’s the least
electronegative of the group, yet
combines directly with most
elements.
Bi + 11n →
210
84
Po + e−
POLONIUM
{
{
{
In November 2006, a
210
84 Po
Russian spy named
Alexander Litvinenko was
poisoned with a lethal
dose of 210Po.
Less than a microgram
was responsible for his
death.
Po decayed through alpha
emission, heavily
damaging vital organs.
→
206
82
Pb +
4
2
α
5
SOURCES
{
{
{
Atkins and Shriver. Inorganic Chemistry. New
York: W.H. Freeman and Company, 2006.
Holland, Rebecca. “Molecule of the Month."
Mustard Gas. Bristol University. 4/10/07
<http://www.bristol.ac.uk/Depts/Chemistry/MOT
M/mustard/mustard.htm>.
WebElements™, the periodic table on the WWW,
URL: http://www.webelements.com/
Copyright 1993-2007 Mark Winter [The University
of Sheffield and WebElements Ltd, UK]. All rights
reserved. Document served: Tuesday 10th April,
2007
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