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GROUP 14 ELEMENTS

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PHYSICAL PROPERTIES

1) ATOMIC SIZE 

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PHYSICAL PROPERTIES

2) MELTING POINT 

C,Si, Ge

giant molecularstructure

strong covalentbond(holding theindividual atoms

together in a threedimension array) 

Sn, Pb

giant metallicstructure

melting point Pb

higher than Snbecause Pb more closepacked structure thanSn, although Pb has a

bigger size than Sn

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PHYSICAL PROPERTIES

3) ELECTRICAL CONDUCTIVITY 

depends on delocalised electron

C

non-metal(diamond)

it is non-conductor of

electricity

Si, Ge

metalloids

(semiconductor)

Sn, Pb

metals and aregood

conductors ofelectricity

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TETRACHLORIDES AND OXIDES OF GROUP 14

ELEMENTS 

All of tetrachlorides of Group 14 elements arecovalent compounds with simple molecularstructures

The atoms of Group 14 undergoes sp3 hybridisation

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VOLATILITY OF TETRACHLORIDE 

The intermolecular forces holdingsimple molecular compounds are

weak Van Der Waals forces ofattraction.

All tetrachloride of Group 14elements are volatile liquids with low

melting point and boiling point

Going down the group Van Der Waalsforces of attraction increase

(molecular size increase) hence themelting point and boiling point of the

tetrachloride increase

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THERMAL STABILITY OF TETRACHLORIDE 

Going down group 14 the bond length ofM-Cl increase and become weaker

the thermal stability of the tetrachloridesdecreases ( less stable going down thegroup)

CCl4, SiCl4, GeCl4 are stable even at hightemperature

SnCl4  decomposes into SnCl2 when heated at150oC

PbCl4 decomposes into PbCl2 on slightwarming 

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H YDROLYSIS OF TETRACHLORIDE 

All the tetrachlorides except CCl4 are easilyhydrolysed by water with released of white fumes

of hydrogen chloride

The elements use the empty d orbitals in theouter shell to form dative bonds with watermolecules 

Tetrachloromethane CCl4 does not undergohydrolysis because carbon atom has noavailable d orbitals and atomic radius ofcarbon is very small.

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OXIDATION STATE 

Group 14 elements form 2 series of oxides with

oxygen:

i. Monoxide MO → +2 

- two p-electron are used in bonding- C and Si → covalent ,

Ge → ionic with covalent character,

Sn and Pb → predominantly ionic

ii. Dioxide MO 2 → +4

all 4 valence electrons are used in bonding

(covalent)

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RELATIVE STABILITY OF +2 AND +4 OXIDATION

STATES OF GROUP 14 ELEMENTS 

-Oxidation +2 stable for element in the bottom,

oxidation +4 stable for element in the top

Ge4+ (aq) + 2e→  Ge2+ (aq) Eº = -

1.60 V

Sn4+ (aq) + 2e→  Sn2+ (aq) Eº = +0.15 V

Pb4+ (aq) + 2e→  Pb2+ (aq) Eº = +1.69 V

- Eº value more positive ↓ Group the tendency M4+

 → M2+ increases

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Pb2+ is more stable than Pb4+ because of the inert

pair effect

Valence electronic configuration 6s2 6p2

High difference energy level between 6s2 and 6p2 It is difficult for 6s electrons to be promoted to the

6p

Two 6s electrons will remain as an inert pair that

will not be involved in a chemical bonding

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SILICON, SILICONE AND SILICATES 

Silicates are compounds containing silicon and oxygen

- The basic init in all silicates is tetrahedral ion, SiO44- Single chain silicate

-When two oxygen atoms per unit tetrahedron are shared to form

single chain → pyroxenes 

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When all four oxygen atoms per unit tetrahedron

are shared, a 3D structure formed → quartz 

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TIN ALLOYS 

Tin is used in the plating of iron / steel container

- Tin is also used in making of alloys

Alloy  Composition 

Bronze  70% Cu, 30%Sn 

Pewter   95% Sn, 3% Cu,

1% Sb 

Solder   30% Sn, 70% Pb