Inorganic Group 14 C,Si,Ge,Sn,Tb

8/9/2019 Inorganic Group 14 C,Si,Ge,Sn,Tb

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Allotropes of carbon

1. Graphite

Stable at room temp. & pressure

At high pressure & temp, transforms to diamond

Carbon arranged in hexagonal rings

Good conductor of electricity ( electrons move between layers)

Layers held by weak van der Waals forces, gives slippery feeling

2. Diamond

Tetrahedral structure (gives it hardness)

Giant molecular structure with high melting points due to strong covalent bonds

Non- conductor of electricity (no free electrons)

Useful as abrasives (An abrasive is a material that is used to polish surfaces or

smooth rough edges. Most abrasives are very hard, brittle, and heat-resistant)


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3. Fullerene

Like a football, 12 pentagons, 20 hexagons

Used in industries & medicine


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Carbon composite in industry

Concrete

High fibre plastics

Superconductors

Photochromatic glass

Kevlar (synthetic graphite fibre) used as Kevlar ropes, in canoes, as canvas for tents

Firemen suits, bullet-proof jackets


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Silicon and Silicates1. Silicates - silicon atom surrounded by 4 oxygen

atoms

2. Tetrahedral

3. Joined to each other by corners

4. Charges on the anion depends on the number of

corners shared5. Ex : sand, asbestos, granite, mica, clay

6. The anion is sometimes called the orthosilicate

ion.


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1. Primary silicates

2. Chain silicates3. Sheet / layer silicates

4. Giant structure silicates


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Clay1. Kaolinite

1:1 clay

Consists of a tetrahedral silicon / oxygen sheet, joining an octahedral

aluminium / oxygen sheet

Forms a layer structure, held by hydrogen bonds

Due to this, water cannot enter between the layers

So kaolinite does not expand when wet

Used mainly as modeling material and as fillers for plastics, rubber andpaints


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2. Montmorillonite

2:1 clay

No hydrogen bonding between layers

Hence, water can enter between layers and it expands when wet

When dried up, it hardens and shrinks, causes cracks to appear


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Glass Silica melts at around 1710 c

It involves breaking of silicon - oxygen bonds

When cooled, amorphous solid called quartz glass is formed

Substance Glass

Sodium oxide Soda-lime glass

Potassium oxide Hard glass

Lead (ll) oxide Lead glass / flint glass


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Colored glass is produced by introducing oxides of transition

elements into glass

Glass Transition metal oxide added

Ruby glass Copper (l) oxide

Green glass Iron (ll) oxide

Blue glass Cobalt (ll) oxide


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Uses of silicon & its compounds

Silicon is used widely in the electronic

industry to make diodes,transistors, solar

cells and integrated circuits

Also used to make silicones

Silicones are oils, greases or rubberymaterials depending on the chain length


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Silicones

Silicones are oils, greases or rubbery

materials depending on the chain length

Chemically inert, good water repellents

Used as lubricants, hydraulic fluids, electric

insulators


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Uses of tin will not rust

Used widely for making alloys Used in the plating of

iron / steel to form tin cans

As long as the tin layer is not scratched, the iron

beneath

Inorganic Group 14 C,Si,Ge,Sn,Tb

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