What is variable valency? Give two examples of elements that show variable valencies.

• The combining capacity of an element is known as its valency.
• The valency of an element is equal to the number of electrons an element loses, gains, or shares during a chemical bond formation.
• Certain elements have a tendency to show different valencies in different molecules. Such elements are said to have variable valency.
• For example - Iron shows a valency of $+2\mathrm{in}{\mathrm{FeCl}}_2$ and $+3\mathrm{in}{\mathrm{FeCl}}_3$.