Question

Explain the term ‘variable valency’. Copper having electronic configuration 2, 8, 18, 1 exhibits variable valency. Give reason for the same and name the compound CuCl and CuCl₂.

Answer 1

Variable Valency

When elements have more than one valency it is called variable valency.

In case of copper (Cu), it has valency ‘1’ and ‘2’ i.e. it can loss or gain 1 or 2 electrons to make different compounds. For example CuCl and CuCl₂.

In compound cuprous chloride (CuCl), the valency of Cu is one as only one chlorine atom is needed for the formation of CuCl.

In compound cupric chloride (CuCl), the valency of Cu is two as here two chlorine atoms is needed for the formation of CuCl₂.