Here's why:

* Covalent bonds involve the sharing of electrons between atoms.

* Nonpolar covalent bonds occur when the electrons are shared equally between the two atoms. This happens when the atoms have similar electronegativity (the ability to attract electrons).

* Electronegativity is a measure of an atom's ability to attract electrons.

* Because the electrons are shared equally, there is no separation of charge, resulting in an electrically symmetrical bond.

Examples of nonpolar covalent bonds:

* The bond between two hydrogen atoms (H-H) in a hydrogen molecule.

* The bond between two chlorine atoms (Cl-Cl) in a chlorine molecule.

Let me know if you'd like more information!