inorganic chemistry : group 14
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Prepared by Chua Chuen Yang.TRANSCRIPT
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Group 14: C,Si,Ge,Sn,Pb
MembersChua Chuen YangKoay Xian Young
JasroopEdward Choi
Harkeerat
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Variation in Physical Properties
Element C Si Ge Sn Pb
Proton no. 6 14 32 50 82
Atomic radius (mm)
0.077 0.111 0.125 0.145 0.153
Ionisation energy
1090 790 760 710 716
Electronegativity 2.50 1.90 2.01 1.96 2.33
Electrical Conductivity
Non-conductor
Except graphite
Semiconductor Conductor
Melting Point 3527 1410 937 232 327
Boiling Point 4027 2900 2830 2602 1750
Structure Giant covalent structure Giant metallic
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Oxidation States of +2 and +4
- elements have valence shell configuration of ns2 np2, thus the +2 oxidation involves s orbitals, while the +4 oxidation involves s & p orbitals.
- +4 oxidation state is stable (heat) for elements on top of the group.
- +2 oxidation state is stable for elements at the bottom of the group, especially Pb.
- Sn2+ & Ge2+ ions are reducing agents due to tendency of being oxidised.
- Pb2+ ions are oxidising agents due to tendency of reduction.
- Elements forming tetrahydride & tetrachloride compounds are covalent in tetrahedron form.
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Tetrachlorides of Group 14
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Chlorofluorocarbon Compounds
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Oxides of Group 14
Monoxides
Oxides of Group 14
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Examples of monoxide reactions
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Dioxides
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Examples of dioxide reactions
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The Relative Stability of +2 & +4 Oxidation State
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Coordination Number & Catenation
- Number of donor atoms/ligands surrounding a metal atom in a complex ion.
- A dative bond is formed between a ligand & a central atom.
- Si, Ge,Sn & Pb usually form complex ions with coordination number of 6. Lone pair of electrons from ligands are accepted by the empty d-orbitals of the elements.
- Carbon does not form complex ions because it’s in Period 2 with no empty d-orbitals, instead it can form 4 covalent bonds to achieve octet configuration.
- Catenation is the ability of an element to form bonds between atoms of the same element in chain form.
- Carbon undergoes catenation whereas silicon does not form many catenated compounds due to weaker Si - Si bond compared to C - C bond.
- Ge, Sn & Pb does not form catenated compounds.
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Allotropes of CarbonProperties Diamond Graphite Fullerene
Structure Tetrahedron Hexagonal rings 20 hexagons & 12 pentagons in a spherical
shape.
Bonding Strong covalent bonds.
Strong covalent bonds , layers of hexagonal
rings are held by weak van der Waals forces
Strong covalent bonds
Type of hybridisation
sp³ sp² sp²
Conductivity Non-conductor due to lack of free electrons
Conductor due to free electrons.
Conductor, a.k.a. Superconductor
Hardness Hard Soft Hard
Uses Glass cutter Pencil leads, ribbons for typewriters
Microelectronics industry
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Relative Stability of Diamond & Graphite- The enthalpy of combustion of diamond is -3954 kJmol⁻¹ whereas for graphite is -393.4kJmol⁻¹.- Graphite is more energetically stable while diamond is more kinetically stable, which means diamond is more likely to change to graphite but at a extremely slow rate.
Carbon Composite in Industry- Formed from high temperature heating of amorphous carbon to form graphite fibres, which is interwined with plastics to form a strong structure.
Examples of carbon composite compounds are:Composite Compound Uses
Carbon laminates (graphite & epoxy) Aircrafts, boat hulls
Kevlar (carbon fibres & epoxy) Canvas for tents, body armor
Carbon & fibreglass Sports equipment eg. rackets
Tungsten carbide (tungsten & carbon alloy) Cutting tools, abrasive
Carbon concrete (carbon fibre & concrete) Construction of buildings & roads
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Silicon & Silicates
- The basic unit of silicates is a tetrahedron unit, (SiO₄)⁴⁻ which can be polymerised.
- Silicate classification is based on where the silicate units are bonded together. ( a) Orthosilicates -The simplest silicate, eg. zircon & calcium silicate.
( b) Pyrosilicates - 2 units of silicate joined together by sharing an oxygen atom, eg. Scandium & zinc mineral. ( c) Cyclic silicates - 2 oxygen atoms in each tetrahedron unit is shared & 3 units are joined to form a ring structure, eg. wollastonit, benitoit & beryl.
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( d) Chain silicates - a single chain silicate (pyroxene) is formed when 2 oxygen atoms at 2 corners of a unit is shared with other units, eg. sodium silicate. - Amphiboles are formed when 2 single chains silicates join together by sharing oxygen atoms, eg. asbestos.
( e) Sheet silicates - An infinite 2D sheet structure resulting from a unit sharing 3 corners or 3 oxygen atoms. - intramolecular bond inside the sheets are strong covalent bonds while intermolecular forces between the sheets are weak van der Waals forces. - eg. Talcum powder, aluminosilicate, kaolin & montmorillonite.
( f) 3D silicates - all 4 angles of the silicate anion,SiO₄⁴⁻ are shared by 4 other units to form a 3D lattice, eg. quartz, cristobalite, feldspar & zeolite.
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Glass- main component is silica, addition of metal oxides during manufacturing process produce coloured glasses such as Fe³⁺ (brown-yellow), Fe²⁺ (green),Co²⁺ (dark blue) & Cu²⁺ (red).
Glass Composition Characteristics Uses
Soda glass SiO₂ , Na₂CO₃, CaCO₃
Transparent, low melting point, not resistant to heat & chemical reactions.
Glass containers, window panes, mirrors, bottles, light bulbs.
Borosilicate glass SiO₂, B₂O₃, Na₂O, Al₂O₃
Heat resistant, low thermal expansion, resistant to corrosive materials
Test tubes, cooking wares
Quartz glass SiO₂ Low thermal expansion, high transparency
Optical studies, eg. Lenses,mirrors & glass rods
Lead glass crystal (crystal glass)
SiO₂, PbO₂, Na₂O High refractive index & density
Lens & prisms in labs, decorative glassware.
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Silicone- Produced from complete hydrolysis of chlorosilane which is substituted twice by alkyl/aryl.
- The Si-O bond is very strong, giving silicone the following characteristics: ( a) Resistant to oxidation,heat & chemical reactions ( b) Waterproof & non-stick ( c) Good electrical insulator ( d) Prevents the formation of foam
- Uses of silicone compounds are silicone rubber, resin & silicone oils.
Tin- Extracted from cassiterite ore (SnO₂)
- Main use is to make cans & alloys.
-Alloys for tin are : (a)Solder Tin-lead alloy used for soldering. (b)Pewter Tin-copper-antimony alloy used to make souvenirs.
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