Chemical Reactions of Non-Metals

Non-metals are electronegative in nature. They generally have 5, 6 or 7 electrons in their valence shells. They have tendency to form anion by gaining electrons.

1. Reaction with Oxygen

Non-metals react with oxygen on heating or burning to form their oxides.

S (s) +O2 (g) → SO2 (g)

C (s) +O2 (g) → CO2 (g)

2H2 (g) +O2(g) → 2H2O (l)

Many non-metals form more than one oxide.

Carbon with limited supply of oxygen on burning forms CO which is a neutral oxide. However, in ample supply of air carbon forms CO2 which is an acidic oxide.

2C (g) + O2 (g) → 2CO

C (g) + O2 (g) → CO2

Nitrogen forms a series of oxides with oxygen:

  1. Nitrous oxide or laughing gas N2O (neutral)
  2. Nitric oxide, NO (neutral)
  3. Dinitrogen trioxide, N2O3 (acidic)
  4. Nitrogen dioxide NO2 (acidic)
  5. Dinitrogen tetroxide, N2O4 (acidic)
  6. Dinitrogen pentoxide, N2O5 (acidic)

Nature of oxides of non-metals

In general, oxides of non-metals are acidic in nature or after dissolving in water they form acids.

Carbon dioxide forms carbonic acid with water.

CO2 (g) + H2O (l) → H2CO3 (aq) (carbonic acid) 

Sulphur trioxide forms sulphuric acid with water.

SO3 (g) + H2O (l) → H2SO4 (l) (Sulphuric acid)

Dinitrogen pentoxide forms nitric acid with water.

N2O5 (g) + H2O (l) → 2HNO3 (l) (nitric acid)