Question

What is the electronegativity difference in a homonuclear diatomic molecule?

Answer 1

Zero.

Explanation:

Electronegativity is a measure of how well an atom can pull electrons to itself.

If two atoms in a bond have different electronegativities, the electron density will be pulled towards the atom with the higher electronegativity, i.e. in `H-Cl`, `Cl` is more electronegative creating, `H^(delta+)-Cl^(delta-)`.

However, if it was the same on both atoms, they would have an equal pull on the electrons.

For example, `H-H` has no dipole. If a bond is non-polar it will form a temporary dipole due to the instantaneous movement of the electrons around both nuclei, sometimes giving an uneven electron distribution.