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.
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
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
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
When hydrogen reacts with oxygen it gives water.
2H2 + O2 ⇨ 2H2O
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
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
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