Group 14: C,Si,Ge,Sn,Pb

MembersChua Chuen YangKoay Xian Young

JasroopEdward Choi

Harkeerat

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

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.

Tetrachlorides of Group 14

Chlorofluorocarbon Compounds

Oxides of Group 14

Monoxides

Oxides of Group 14

Examples of monoxide reactions

Dioxides

Examples of dioxide reactions

The Relative Stability of +2 & +4 Oxidation State

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.

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

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

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.

( 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.

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.

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.

THE END