Question

What are variable valencies? State a few examples.

Answer 1

Valency: The capacity with which an atom of an element combines chemically with the atom(s) of another element is called the combining capacity or valency of the element.

Variable valency: There are Some elements which have different capacities to combine with different elements.

• It depends on the nature of the reaction.
• This property of having different capacities to combine with different elements is known as variable valency.

For example,

• $$\begin{gathered} \mathrm{Valency}\mathrm{of}\mathrm{Iorn}\left(\mathrm{Fe}\right)\mathrm{is}+2\mathrm{and}+3. \\ \mathrm{Valency}\mathrm{of}\mathrm{Copper}\left(\mathrm{Cu}\right)\mathrm{is}+1\mathrm{and}+2. \\ \mathrm{Valency}\mathrm{of}\mathrm{Lead}\left(\mathrm{Pb}\right)\mathrm{is}+2\mathrm{and}+4. \\ \mathrm{Valency}\mathrm{of}\mathrm{Mercury}\left(\mathrm{Hg}\right)\mathrm{is}+1\mathrm{and}+2. \\ \mathrm{And}\mathrm{Valency}\mathrm{of}\mathrm{Tin}\left(\mathrm{Sn}\right)\mathrm{is}+2\mathrm{and}+4 \end{gathered}$$