# Metals and Non-metals

## Physical properties of non-metals

Hardness: Non-metals are not hard rather they are generally brittle. But diamond is exception. It is the hardest among naturally occurring substances.

State: Non-metals may be solid, liquid or gas, at room temperature.

Lustre: Non-metals have dull appearance. Iodine is an exception, as it has lustre.

Sonority: Non-metals are not sonorous, i.e. they do not produce a typical sound on being hit.

Conduction: Non-metals are bad conductor of heat and electricity. Graphite is an exception, as it is a good conductor of electricity.

Malleability and ductility: Non-metals are non-malleable and non-ductile. We cannot make thin sheets or wires from non-metals.

Melting and boiling point: Non-metals generally have low melting and boiling points.

Density: Most of the non-metals have low density.

Color: Non-metals are of many colors.

## Chemical properties of Non-metals

#### Reaction of non-metals with oxygen

When a non-metal reacts with oxygen, then oxide is formed. Following is the general equation for this reaction.

Non-metal + Oxygen ⇨ Non-metal oxide

##### Carbon with Oxygen

When carbon reacts with oxygen, carbon dioxide is formed. This is an exothermic reaction, which means het is evolved in this reaction.

C + O2 ⇨ CO2 + Heat

When carbon is burnt in insufficient supply of air, it forms carbon monoxide. Carbon monoxide is a toxic substance. Inhaling carbon monoxide may prove fatal, even in small quantities.

2C + O2 ⇨ 2CO + Heat

##### Sulphur with Oxygen

When sulphur reacts with oxygen then sulphur dioxide is formed. Sulphur reacdily reacts with oxygen. So, when sulphur is exposed to air then it catches fire.

S + O2 ⇨ SO2

##### Hydrogen with Water

When hydrogen reacts with oxygen it gives water.

2H2 + O2 ⇨ 2H2O

### Non-metal Oxide

Non-metal oxides are acidic in nature. This is evident from the fact that solution of non-metal oxides turns blue litmus red. Following are some examples of formation of acid when non-metallic oxide is dissolved in water.

When carbon dioxide is dissolved in water, it gives carbonic acid.

CO2 + H2O ⇨ H2CO3

When sulphur dioxide is dissolved in water, it gives sulphurous acid.

SO2 + H2O ⇨ H2SO3

When sulphur dioxide reacts with oxygen, it gives sulphur trioxide

2SO2 + O2 ⇨ 2SO3

When sulphur trioxide is dissolved in water, it gives sulphuric acid.

SO3 + H2O ⇨ H2SO4

#### Reaction of non-metal with chlorine

When a non-metal reacts with chlorine, then chloride is formed. General equation for this reaction is given below.

Non-metal + Chlorine ⇨ Non-metal chloride

When hydrogen reacts with chlorine, then hydrogen chloride is formed. Following is equation for this reaction.

H2 + Cl2 ⇨ 2HCl

When phosphous reacts with chlorine, then phosphorus trichloride is formed. Following is equation for this reaction.

P4 + 6Cl2 ⇨ 4PCl3