Question

Why are homonuclear diatomic molecules non-polar?

Answer 1

Because the elements that comprise a homonclear halogen molecule, `X_2`, clearly have equal electronegativies.

Explanation:

A homonculear diatomic molecule, `X_2`, is composed of 2 halogen atoms, which have the same electronegativity. Given this, there can be no charge separation, and no possibility of polarity in the `X-X` bond.

Molecules such `I-Cl` or `F-Br` can certainly exist. Such molecules would exhibit a dipole as there would be unequal sharing of electron density.