Chemical properties of non-metals

CHEMICAL PROPERTIES OF NON-METALS

The chemical properties of non-metals are determined by:

• Electronic configuration. 
• Valency.
• Oxidising nature. 

ELECTRONIC CONFIGURATION:

Non-metals have 4 or 5 or 6 or 7 electrons in their valence shells. [Exception: Hydrogen and helium are non-metals but they have just one and two electrons in their valence shells respectively]. 

VALENCY: 

Non-metals have valencies –3 or –2 or – 1. They accept electrons in their valence shells to complete their octets, i.e., they form anions during chemical combination. 

OXIDISING NATURE:

Non-metals tend to gain electrons from metals during chemical combination i.e., they oxidize the metals during chemical combination and themselves get reduced in the process. 

Reaction of non-metals with oxygen 

• Non-metals react with oxygen (air) on heating to form their respective oxides. Most of these oxides are acidic in nature and they turn moist red litmus paper blue. 

Non – metal + Oxygen Non-metallic oxide 

(i) Carbon burns in oxygen to produce carbon dioxide.

(ii) Sulphur burns in oxygen to produce sulphur dioxide 

• Some non-metallic oxides are natural e.g., water (H2O), carbon monoxide (CO), nitric oxide (NO) and nitrous oxide (N2O). 

(iii) Hydrogen burns in oxygen to produce water, which is a neutral oxide i.e., it does not change the colour of indicators. 

Reaction of acidic oxides and acids with bases / alkalis

Carbon dioxide and sulphur dioxide react with sodium hydroxide to produce the salts sodium carbonate and sodium sulphite respectively, along with water. 

Acidic oxide + Base Salt + Water

Reaction with water

(i) Carbon dioxide dissolves in water and forms carbonic acid. 

(ii) Sulphur dioxide gives sulphurous acid with water. 

Reaction of non-metals with acids

• Non-metals do not react with dil. HCl or H2SO4. But they react with concentrated acids. 

Some of the reactions are as follows:

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