Here's why:

* Nonmetals have high electronegativity: This means they have a strong attraction for electrons.

* Equal sharing: When two identical nonmetals bond, they have the same electronegativity. This means they share the electrons equally, resulting in a nonpolar covalent bond.

Examples:

* Oxygen (O2): Two oxygen atoms share electrons to form a double covalent bond.

* Nitrogen (N2): Two nitrogen atoms share electrons to form a triple covalent bond.

* Chlorine (Cl2): Two chlorine atoms share electrons to form a single covalent bond.