Chapter 22
Chemistry of the
Nonmetals
Nonmetals
Nonmetals
Except for
hydrogen,
the
nonmetals
are found in
the upper
right-hand
corner of the
periodic
chart.
Nonmetals
Periodic Trends
Within a group,
smaller atoms
are more likely
to form -bonds
because they
can get closer
to other atoms.
Nonmetals
Periodic Trends
As a result, CO2 contains
two -bonds, and SiO2 is
a network solid with only
-bonds.
Nonmetals
Hydrogen
• Discovered by Henry
Cavendish (1731-1810)
• Three isotopes
 Protium (1H)  99.98% of
all hydrogen
 Deuterium (2H)  0.016%
 Tritium (3H)  Radioactive
Nonmetals
Properties of Hydrogen
• Unique
Does not belong to any group
• Very low melting (-259C) and boiling
(-253C) points
• Very large bond enthalpies
Reacts slowly
Reactions are generally quite exothermic
Nonmetals
Hydrogen Production
• Commercially produced from reaction of methane
(CH4) with steam at 1100C or carbon and steam
above 1000C
CH4 (g) + H2O (g)  CO (g) + 3 H2 (g)
CO (g) + H2O (g)  CO2 (g) + H2 (g)
C (s) + H2O (g)  H2 (g) + CO (g)
• Production from electrolysis of water not energyefficient
Nonmetals
Uses of Hydrogen
• Most hydrogen used
to produce ammonia
(NH3) in the Haber
process
• Also used to
produce methanol
(CH3OH)
CO (g) + 2 H2 (g)  CH3OH (g)
Nonmetals
Uses of Hydrogen
2 H2 (g) + O2 (g)  2 H2O (g) H = -483.6 kJ
• Using hydrogen as a fuel would have
many advantages:
Highly exothermic reaction
Water is only product
• Problem: How will we make the H2?
Nonmetals
Hydrides
• Three types
Ionic
Metallic
Molecular
Nonmetals
Ionic Hydrides
• Formed between
hydrogen and alkali
metals or heavy
alkaline earth metals
(Ca, Sr, Ba)
• Very strong bases
and reducing agents
• React readily with
water, so must be
stored free from
moisture
Nonmetals
Metallic Hydrides
• Formed between hydrogen and
transition metals, often in unusual ratios
e.g., TiH1.8
• Retain electrical conductivity and other
metallic properties
Nonmetals
Molecular Hydrides
• Formed between
hydrogen and
nonmetals or
metalloids
• Usually gases or
liquids at room
temperature and
normal atmospheric
pressure
Nonmetals
Noble Gases
• Extremely stable and
unreactive
• Liquid He (boiling
point 4.2 K) used as a
coolant
• Ne used in electric
signs
• Ar used in light bulbs
and as insulating gas
between panes in
thermal windows.
Nonmetals
Xenon Compounds
• Of all noble gases, Xe
can be forced to form
compounds most easily
• KrF2 also known, but
decomposes at -10C
Nonmetals
Halogens
• Have outer electron
configurations of
ns2np5
• Large electron
affinities and
ionization energies
• Tend to accept one
electron to form
anion
Nonmetals
Halogens
• All have -1 oxidation
state
• All but fluorine also
have positive
oxidation states up
to +7 when bonded
to more
electronegative
atoms
Nonmetals
Properties of Halogens
• Tend to be good
oxidizers, due to
their
electronegativity
• Can oxidize
anions of
halides below
them on
periodic chart
Nonmetals
Properties of Halogens
• Fluorine has unusually high reduction potential
• It can easily oxidize water:
F2 (aq) + H2O (l)  2 HF (aq) + 1/2 O2 (g) E = 1.80 V
Nonmetals
Uses of Halogens
• Fluorine reacts to
form fluorocarbon
compounds used as
lubricants,
refrigerants and
plastics.
• Teflon is a polymer
of fluorocarbons.
Nonmetals
Uses of Halogens
• Chlorine is the most-used halogen.
HCl
Plastics
Bleaches
Water purification
Nonmetals
Uses of Halogens
• Bromine is the anion
for silver in
photographic film.
• KI is added to table
salt as a dietary
supplement.
Nonmetals
Hydrogen Halides
• Aqueous solutions of HCl,
HBr, and HI are, of course,
strong acids.
• HF and HCl can be produced
by reacting salts with H2SO4.
• Br- and I- oxidize too easily,
so one must use a weaker
oxidizing acid, like H3PO4.
Nonmetals
HF
• Hydrofluoric acid
reacts with silicates,
components of most
types of glass.
• This reaction causes
glass to etch.
• Therefore, HF is
usually stored in
plastic containers.
Nonmetals
Oxyacids and Oxyanions
• Oxyacid strength increases with increasing
oxidation number of central halogen
• Oxyacids are strong oxidizers.
• Oxyanions generally more stable than
corresponding acids
Nonmetals
Perchlorates
While generally quite
stable, perchlorates
become exceedingly
strong oxidizers when
heated, and are used
as rocket fuel.
Nonmetals
Oxygen
• Joseph Priestley
discovered oxygen
in 1774.
• Lavoisier give it its
name, which means
“acid former.”
• Most commercial
oxygen is obtained
from air.
Nonmetals
Oxygen
• Exists as one of two allotropes, O2 and
O3 (ozone)
• Forms very strong bonds
Reactions of oxygen-containing
compounds have high activation energies
Reactions can be very exothermic, even to
point of being explosive
Nonmetals
Uses of Oxygen
• Oxidizing agent
 Bleach pulp and
paper
 Medical uses
 Welding (with
acetylene)
Nonmetals
Ozone
• Bluish gas with sharp odor
• Extremely irritating to
respiratory system
• Stronger oxidizer than O2
 Used to purify water
• Used in organic synthesis
• Absorbs UV light in upper
atmosphere
Nonmetals
Oxides
• Oxygen is second-most
electronegative element
 Always has negative
oxidation state except
when bonded to F
• Acidic oxides like SO2
and SO3 form acids
when exposed to water.
• Basic oxides like BaO
form hydroxide ion
when they react with
water.
Nonmetals
Peroxides
• Oxygen has
oxidation state of -1
• O-O bond very weak
 Decomposition of
peroxides can be
dangerously
exothermic
Nonmetals
Superoxides
• Oxygen has oxidation
state of -1/2
• The most active metals
(K, Rb, Cs) form
superoxides through
reaction with O2
• React with H2O to form
O2
 Source of O2 in selfcontained breathing
devices
Nonmetals
Other Group 6A Elements
• Have oxidation states of -2 as well as several
positive oxidation states
• Can have expanded octets
Nonmetals
Selenium and Tellurium
• Anions in minerals with
Cu, Pb, Ag, and Au
• Found as helical chains
of atoms
• Selenium not electrically
conductive in dark, but
quite so in light
 Used in light meters,
photosensors, and
photocopiers
Nonmetals
Sulfur
• Solid, yellow
compound found in
8-membered ring
• As heated to
melting, ring breaks
and sulfur becomes
viscous, reddishbrown liquid
Nonmetals
Sulfur
• Most sulfur used for H2SO4 and for
vulcanization of rubber
Nonmetals
Pyrites
• Contain disulfide
ion, S22-, the sulfur
analog of peroxide
• Found in minerals
like iron pyrite (fool’s
gold)
Nonmetals
Sulfides
• To say that many sulfides have rather
unpleasant odors is a gross
understatement.
H2S is emitted by rotten eggs.
• Many minerals like galena (PbS) and
cinnabar (HgS) are sulfides.
Nonmetals
Sulfur Oxides, Oxyacids, and
Oxyanions
• SO2 is a poison, particularly to lower
organisms.
Used to sterilize dried fruit and wine
Dissolves in H2O to form H2SO3
• Sulfites and bisulfites added to foods
and wines to kill bacteria
Nonmetals
Sulfur Oxides, Oxyacids, and
Oxyanions
• Sulfuric acid
 Strong acid
 Good dehydrating agent
 Decent oxidizer
Nonmetals
Sulfur Oxides, Oxyacids, and
Oxyanions
Sulfate
• Thiosulfate ion resembles sulfate ion
(a S replaces one of the O’s in sulfate)
• Sodium thiosulfate pentahydrate
(Na2S2O35 H2O) used in photography
to remove unexposed AgBr from film
as soluble complex of thiosulfate
Nonmetals
Thiosulfate
Nitrogen
• Discovered in 1772
by Daniel Rutherford
• Makes up 78% of
Earth’s atmosphere
• Can exist in
oxidation states
from -3 to +5
Nonmetals
Nitrogen
• Many nitrogencontaining
compounds
strong oxidizers
• N2 made into
NH3 in Haber
process
 NH3 is
precursor to
many other
compounds
Nonmetals
Ammonia
• Hydrazines made from
ammonia
 One intermediate is
chloramine (NH2Cl),
poisonous compound
produced when household
ammonia and hypochlorite ion
in bleach are mixed
• Hydrazines are strong
oxidizers used in rocket
fuels
Nonmetals
Oxides and Oxyacids
• Nitrous oxide (N2O; laughing gas) was
the first general anesthetic.
• It is also used in aerosol products like
whipped cream.
Nonmetals
Oxides and Oxyacids
• Nitric oxide (NO) is a slightly toxic, colorless gas.
 Recently shown to be neurotransmitter in humans
involved in vasodilation
• Reacts with O2 in air to produce nitrogen dioxide,
NO2
Nonmetals
Oxides and Oxyacids
• Nitric acid
 Strong acid and
oxidizer
 Used in fertilizer and
explosive production
(TNT, nitrocellulose,
nitroglycerine)
• Nitrous acid
 Less stable, yet
weaker acid than
HNO3
Nonmetals
Other Group 5A Elements
This group contains nonmetals (N and P), a
metal (Bi), and metalloids (As and Sb).
Nonmetals
Phosphorus
• Two allotropes
White phosphorus
(P4)
• Highly strained
• Bursts into flames if
exposed to O2 in air
Red phosphorus
• Very stable
Nonmetals
Oxyphosphorus Compounds
Phosphorus(III) oxide
(P4O6) and
phosphorus(V) oxide
(P4O10) are anhydride
forms of phosphorous
(H3PO3) and phosphoric
(H3PO4) acids
Nonmetals
Oxyphosphorus Compounds
• These acids condense to
form polymeric forms.
• Phosphoric acid and
phosphates are found in
detergents, fertilizers,
and important
biomolecules like DNA,
RNA, and ATP.
Nonmetals
Carbon
• Exists as four allotropes:
 Graphite
 Diamond
 Fullerenes
 Carbon nanotubules
• Graphite converted to diamond
(at 100,000 atm and 3000C)
for industrial uses
Nonmetals
Carbon Oxides
• Carbon monoxide (CO)
 Odorless, colorless gas
 Binds preferentially to iron in hemoglobin,
inhibiting O2 transport
 Used as fuel, reducing agent in metallurgy, and
precursor to organic compounds
• Carbon dioxide (CO2)
 Used to carbonate beverages, decaffeinate
products (in its supercritical form) and as a
refrigerant (as Dry IceTM)
Nonmetals
Carbonic Acid and Carbonates
• Dissolved CO2 in water is
in equilibrium with
carbonic acid, H2CO3
• Carbonates found as
minerals like calcite,
CaCO3, the primary
constituent of limestone
Nonmetals
Silicon
• Second most
abundant element in
Earth’s crust
• Semiconductor used
in making transistors
and solar cells
• Purified by zonerefining
Nonmetals
Silicates
• Have a central
silicon surrounded
by 4 oxygens
• In disilicate, two
tetrahedral
structures share one
oxygen
Silicate
Disilicate
Nonmetals
Silicates
• These units can
further connect into
sheets or strands.
• Talc and asbestos
are two examples of
molecules
containing these
structures.
Nonmetals
Boron
• The only nonmetallic
Group 3A element
• Compounds of boron
and hydrogen are
called boranes.
• Because boron does
not have a filled octet,
structures such as
diborane, in which two
borons share one
hydrogen are possible.
Nonmetals
Boron
Borane anions, such
as borohydride, BH4-,
are good reducing
agents and sources of
hydride ion.
Nonmetals