Nonmetals
• Except for hydrogen, the nonmetals are found in the upper right‐hand corner of the periodic chart.
Chemistryofthe
Nonmetals
Chapter 20
Chemistry: The Central Science 3rd Edition (Australian Edition)
Brown, LeMay, Bursten, Murphy, Woodward, Langford, Sagatys, & George PeriodicTrends
• Within a group, smaller atoms are more likely to form ‐bonds because they can get closer to other atoms.
Atomic radius increases down a group!
PeriodicTrends
• As a result, CO2
contains two ‐bonds, and SiO2 is a network solid with only ‐
bonds.
Carbon allotropes
Diamond, graphite, carbon nanotubes,
graphene, buckministerfullerene
Silicon Allotropes = 1!
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Hydrogen
Deuterium uses include R&D in chemistry &
life sciences, nuclear reactors, & weapons
Tritium uses include nuclear weapons, R&D
on metabolism of new drugs
• First isolated by Henry Cavendish (1731‐1810)
• Antoine Lavoisier named it hydrogen
• Most abundant element in the universe
• Most hydrogen on earth is bound to oxygen (H2O)
• There are 3 natural isotopes of hydrogen
• Forms + ion less readily than Li
• Ionisation energy ~ 1312 (vs 520 for Li) kJ mol‐1
• Can be placed above F in the periodic table
• Can form a negative ion (Hydride ion H‐)
• H2 (dihydrogen or molecular hydrogen)
• Colourless, odourless, tasteless gas at room temperature
• Non‐polar, low m.p. & b.p. (‐259 and ‐253 °C)
• High bond enthalpy but easily activated by heat, sparks, irradiation, or catalysts
• Reacts rapidly and exothermically with variety of substances
Preparation&UsesofHydrogen
Industrial Scale Production via Steam Reforming of Natural Gas →
Can use coal (mostly carbon)
→
Water Electrolysis
→
BinaryHydrogenCompounds
• Ionic Hydrides
• Alkali metals
• Also Ca, Sr, & Ba….electronegativity?
• Hydride ion H‐ is very basic, good reducing agent
• CaH2 + H2O  __?_+__?____
• CO + H2 = Water Gas
• Water gas used to make fuels & other hydrocarbons • SASOL – CTL technologies
Re‐write the natural gas and steam rxn with water gas as the product
PropertiesofHydrogen
• Can be found above Li in the periodic table
• Metallic Hydrides
• Transition metals and H2
• Can form non‐stoichiometric compounds e.g. TiH1.8
• Can be described as a solution of hydrogen atoms in a metal – embrittlement
• Pd important industrially
• Molecular Hydrides
• Non metals and semi‐metals
Main uses include, Ammonia synthesis, Petrochemical industry, Metallurgical processes
2
BinaryHydrogenCompounds
CloserLookatCaH2 e.g.
• CaH2 + H2O  __?_+__?____
• H— acts as a base, thus:
H— + H2O  OH—(aq) + H2(g)
• Overall:
• CaH2 + 2H2O  Ca(OH)2(aq) + 2H2(g)
Ionic Hydrides
Ca is in group IIA
Alkaline earth metals
• Alkali metals
• Also Ca, Sr, & Ba….electronegativity?
• Hydride ion H‐ is very basic, good reducing agent
• CaH2 + 2H2O  Ca(OH)2(aq) + 2H2(g)
Metallic Hydrides
1. How many grams of CaH2 would you need to produce 1000L of hydrogen gas at 25 °C and 1.0 bar?
a) What is the volume, in L, occupied by the CaH2?
859.83g
• Transition metals and H2
• Can form non‐stoichiometric compounds e.g. TiH1.8
• Can be described as a solution of hydrogen atoms in a metal – embrittlement • Pd important industrially
Molecular Hydrides
• Non metals and semi‐metals
0.506L
HydrogenEconomy
Oxygen
• Joseph Priestley discovered oxygen in 1774.
• Lavoisier gave it its name, which means “acid former.”
• Most commercial oxygen is obtained from air.
3
PropertiesofOxygen
• It has two allotropes, O2 and O3 (ozone)
• Colourless odourless gas
• m.p. ‐218 °C, and b.p. ‐183 °C
• Slightly soluble in water
• Can accept or share two electrons
[He] 2s2 2p4
• It forms very strong bonds
UsesandPreparationof
Oxygen
Uses
Preparation
• Oxidizing agent
• Commercially • Bleach pulp and paper
• Medical uses
• Welding (with acetylene)
• Liquefied air
• Reactions of oxygen‐containing compounds have high activation energies.
• Reactions can be very exothermic, even to the point of being explosive.
Ozone
Oxides
• Oxygen is second‐most electronegative element
• Always has negative oxidation state except when bonded to F.
• Bluish gas with sharp odor.
• Extremely irritating to respiratory system.
• Stronger oxidiser than O2
• Used to purify water.
• Used in organic synthesis.
• Absorbs UV light in upper atmosphere.
• Acidic oxides like SO2 and SO3 form acids when exposed to water.
SO2 (g) + H2O (l)  H2SO4 (aq)
• Basic oxides like BaO form hydroxide ion when they react with water.
BaO (s) + H2O (l)  ? (aq)
BaO (s) + H2O (l)  Ba(OH)2(aq)
Metals with variable oxidation states show a decrease in basic character as the oxidation state increases
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Superoxides
CloserLookatSuperoxideE.g.
• Oxygen has oxidation state of ‐½
• The most active metals (K, Rb, Cs) form superoxides through reaction with O2
• React with H2O to form O2
KO2(s) + H2O(l)  K+(aq) + ? + ?
4 KO2(s) + 2 H2O(l)  4 K+(aq) + 4 OH—(aq) + 3 O2(g)
CO2(g) + OH—(aq)  ? + ?
• Source of O2 in self‐contained breathing devices.
CO2(g) + 2 OH—(aq)  H2O(l) + CO32— (aq)
Peroxides
• Here oxygen has an oxidation state of ‐1
OtherGroup16Elements
• Have oxidation states of ‐2 as well as several positive oxidation states.
• Na, Ca, Sr, & Ba form peroxides
• The O‐O bond is very weak
• Decomposition of peroxides can be dangerously exothermic
ns2 np4
• Can have expanded octets.
SF6
SeF6
TeF6
All +6
• 3% by mass sold as an antiseptic
• Industrially concentrated solution used to bleach
Show H2O2 can undergo a
disproportionation
2 H2O2(l)  2 H2O(l) + O2(g)
5
SeleniumandTellurium
• Anions in minerals with Cu, Pb, Ag, and Au.
• Found as helical chains of atoms.
Sulfur
• Solid, yellow compound found in 8‐
membered ring.
• As heated to melting, ring breaks and sulfur becomes viscous, reddish‐brown liquid.
• Selenium not electrically conductive in dark, but quite so in light
• Used in light meters, photosensors, and photocopiers.
Sulfur
• Most of the sulfur is used for the production of H2SO4 and for the vulcanisation of rubber.
Sulfides
• Contain disulfide ion, S22‐, the sulfur analogue of peroxide.
• Found in minerals like iron pyrite (fool’s gold), PbS
(galena), & HgS (cinnabar).
• Many sulfides have rather unpleasant odours
• H2S is emitted by rotten eggs.
6
SulfurOxides,Oxyacidsand
Oxyanions
ProductionofSulfuric Acid(ContactProcess)
Sulfur or an ore of sulfur oxidised in excess air
S s
• SO2 is a poison, particularly to lower organisms
• Used to sterilise dried fruit and wine
• Dissolves in H2O to form H2SO3
AFeS2 s
O2 g →SO2 g
QO2 g →WFeyOx ZSO2 g
Converting the sulfur dioxide into sulfur trioxide
• Sulfites and bisulfites are added to foods and wines to kill bacteria.
V2O5
@
450 °C
2SO g
O2 g ⇌ SO3 g
∆ Dissolving the sulfur trioxide in sulfuric acid
SO g
SO4 l →
O l
Oleum
Dissolving the oleum in water
When dissolved in water they produce SO2
O
CloserLookatH2SO4
l
O l →
SO4 l
SulfurOxides,Oxyacids andOxyanions
Recall section 4.3 in text book ‘Ionisation’
• Sulfuric acid
• H2SO4(aq)  H+(aq) + HSO4—(aq)
• HSO4—(aq) ⇌H+(aq)+ SO42—(aq)
Sulfates
Bisulfites or hydrogen sulfates
• Strong acid
• Good dehydrating agent
• Decent oxidiser!
• manufacture of fertilizers, explosives, dyes, petroleum products, domestic acidic drain cleaner, lead‐acid batteries, mineral processing, fertilizer manufacturing, oil refining, wastewater processing, and chemical synthesis. • Industrial Barometer
7
SulfurOxides,Oxyacids,andOxyanions
• 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.
Nitrogen
• Discovered in 1772 by Daniel Rutherford.
• Makes up 78% of Earth’s atmosphere.
• Can exist in oxidation states from ‐3 to +5.
Note + oxidation states only occur with more electronegative elements Nitridesexample
• Mg and Li when burnt in air can form nitrides (besides oxides)
• Mg + N2  ? Nitrogen
• Many nitrogen‐containing compounds are strong oxidisers.
• N2 is made into NH3 via the Haber process
• NH3 is precursor to many other compounds.
• Most metal nitrides react with water to form a basic solution and ammonia gas
• Mg3N2 + H2O(l)  ? + ?
8
Ammonia
Haber Process
N2 (g) + 3 H2 (g)  2 NH3 (g)
150 – 250 bar, 300 – 550 °C
Fe‐based catalysts
• Hydrazines made from ammonia
• One intermediate is chloramine (NH2Cl), a poisonous compound produced when household ammonia and hypochlorite ion in bleach are mixed.
OxidesandOxyacids
• Nitrous oxide (N2O, laughing gas) was the first general anaesthetic.
• It is also used in aerosol products like whipped cream.
• Hydrazines are strong oxidisers
• used in rocket fuels.
OxidesandOxyacids
• Nitric oxide (NO) is a slightly toxic, colourless gas
• recently shown to be neurotransmitter in humans
• involved in vascodilation
• Reacts with O2 in air to produce nitrogen dioxide, NO2
Oxidesand
Oxyacids
• Nitric acid
• Strong acid and oxidiser
• Used in fertiliser and explosive production (TNT, nitrocellulose, nitroglycerine)
• Nitrous acid
• Less stable, yet weaker acid than HNO3
9
OstwaldProcess
Ammonia is oxidised to NO gas (850 °C & Pt based catalyst)
4NH
5O
→ 4NO
6H O
OtherGroup15Elements
• This group contains nonmetals (N and P), a metal (Bi), and metalloids (As and Sb).
NO gas converted to NO2
2NO
O
→ 2NO
NO2 Dissolved in water
3NO
H O
→ NO
Phosphorus
• Two allotropes
• White phosphorus (P4)
2H
2NO
Oxyphosphorus Compounds
• Phosphorus(III) oxide (P4O6) and phosphorus(V) oxide (P4O10) are anhydride forms of phosphorous (H3PO3) and phosphoric (H3PO4) acids.
• Highly strained
• Bursts into flames if exposed to O2
in air
• Red phosphorus
• Very stable
• There are other allotropes!
•
•
Black (Heat white P under high pressure)
Violet (Heat red in a closed tube)
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OxyphosphorusCompounds
Carbon
• Exists as four allotropes
• These acids condense to form polymeric forms.
•
•
•
•
• Phosphoric acid and phosphates are found in detergents, fertilisers and important biomolecules like DNA, RNA, and ATP.
OxidesofCarbon
• Carbon monoxide (CO)
• Odourless, colourless gas
• Binds preferentially to iron in haemoglobin, 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)
Graphite
Diamond
Fullerenes
Carbon nanotubules
• Graphite converted to diamond (at 100,000 atm and 3000C) for industrial uses.
OxidesofCarbonsInAction!SomeExamples
As a fuel
2 CO(g) + O2(g)  2 CO2(g) ΔH = ‐ 566 kJ
3 CO(g) + Fe2O3(s)  2 Fe(s) + 3 CO2(g) C(s) + O2(g)  CO2(g) Metallurgy
Combustion!
3 O2(g) + C2H5OH(s)  3 H2O(g) 2CO2(g) CaCO3(s) + → CaO(s) + CO2(g) NaHCO3(s) + H+  Na+(aq) + H2O(l) + CO2(g) Heating limestone
To make cement
Baking Soda
During Baking
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CarbonicAcidandCarbonates
• Dissolved CO2 in water is in equilibrium with carbonic acid, H2CO3.
Carbides
• Binary Compounds of Carbon with metals, metalloids and certain non‐metals
• Ionic carbides have the acteylide ion (C22—)
[ C
C ]2—
• Making CaC2
CO2(aq) + H2O(l) ⇌ H2CO3(aq)
• Isoelectronic with N2
• Basic ion
2 CaO(s) + 5 C(s)  CO2(g) + 2 CaC2(s)
• Producing Acetylene
• Carbonates found as minerals like calcite, CaCO3, the primary constituent of limestone.
• Washing Soda (Na2CO3∙10 H2O) – added to soap to precipitate some metal ions that interfere with the actions of soap
2 H2O(l) + CaC2 (s)  Ca(OH)2(aq) + C2H2(g)
• Interstitial Carbides (Tungsten Carbide ‐ WC)
• WC used in making cutting tools – very hard material!
• Covalent Carbides (B & Si)
• SiC – diamond like structure, with similar properties
OtherInorganicCarbon
CarbonComposites
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Silicon
Silicates
• Have a central silicon surrounded by 4 oxygens.
• Second most abundant element in Earth’s crust.
• In disilicate, two tetrahedral structures share one oxygen.
• Semiconductor used in making transistors and solar cells.
• Purified by zone‐
refining.
10‐7%
1ppb
Figure 17.37
SiO2(s) + C  Si(l) + CO(g)
SiCl4(g) + 2 H2(g)  Si(s) + 4 HCl(g)
Silicates
Glass
• Quartz (SiO2) melts at 1600 °C
• Soda lime glass used in bottles & windows
• Contains CaO, Na2O and SiO2
• Deep blue colour of cobalt glass
• Due to CoO in the soda glass
• Replacing Na2O with PbO produces ‘sparkly’ crystal (lead crystal) glass • These units can further connect into sheets or strands.
• Talc and asbestos are two examples of molecules containing these structures.
• Adding B2O3 makes regular lab (& bake ware) glassware Kimix® or Pyrex® 13
Boron
• The only nonmetallic Group 13 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.
Boron
• Borane anions, such as borohydride, BH4‐, are good reducing agents and sources of hydride ion.
• The only important oxide of boron is boric oxide, B2O3, which is the anhydride of the very weak acid, H3BO3 (boric acid).
• Used as a pesticide, additive for fiberglass, nuclear power plants, antiseptic, • The diprotic acid H2B4O7 is called tetraboric acid and its hydrated sodium salt Na2B4O7H2O is borax.
Laundry &
Cleaning Products
Halogens
Halogens
• Have outer electron configurations of ns2np5 , (where n = 2 to 6)
• All have ‐1 oxidation state.
• Large electron affinities and ionisation energies.
• All but fluorine also have positive oxidation states up to +7 when bonded to more electronegative atoms.
• Tend to accept one electron to form anion.
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PropertiesofHalogens
• Tend to be good oxidisers, due to their electronegativity.
PropertiesofHalogens
• Fluorine can easily oxidise water.
F2(aq) + H2O(l)  2HF(aq) + ½O2(g) • Can oxidise anions of halides below them on periodic chart.
UsesofHalogens
• Fluorine reacts to form fluorocarbon compounds used as lubricants, refrigerants and plastics.
• Teflon is a polymer of fluorocarbons.
UsesofHalogens
• Chlorine is the most‐used halogen:
• HCl
• Plastics
• Bleaches (e.g. Jik)
• Water purification
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HydrogenHalides
UsesofHalogens
• Aqueous solutions of HCl, HBr, and HI are strong acids.
• Bromine is the anion for silver in photographic film.
• HF and HCl can be produced by reacting salts with H2SO4.
• KI is added to table salt as a dietary supplement.
• Br‐ and I‐ oxidise too easily, so one must use a weaker oxidising acid, like H3PO4.
Oxyacids andOxyanions
HF
• Hydrofluoric acid reacts with silicates, components of most types of glass.
• This reaction causes the etched effect on glass.
• Oxyacid strength increases with increasing oxidation number of the central halogen.
• Oxyacids are strong oxidisers.
• Oxyanions are generally more stable than corresponding acids.
• Therefore, HF is usually stored in plastic containers.
Table 17.3
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NobleGases
• Extremely stable and unreactive.
• Liquid He (boiling point 4.2 K) used as a coolant.
XenonCompounds
• Of all noble gases, Xe can be forced to form compounds most easily.
• KrF2 also known, but decomposes at ‐10C.
• Ne used in electric signs.
• Ar used in light bulbs and as insulating gas between panes in thermal windows.
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