Define valency by taking examples of silicon and oxygen.

Explanation

The valency of an element is the combining capacity of that element. The valency of an element is determined by the number of valence electrons present in the atom
of that element. `to ` . Valency of Silicon: It has electronic configuration: 2,8,4
Thus, the valency of Silicon is 4 as these electrons can be shared with others to complete octet.
`to` Valency of Oxygen : It has electronic congifguration : 2, 6
Thus,the valency of oxygen is 2 as it will gain 2 electrons to complete its octet.