In contrast, atoms of similar electronegativities
that bond together through an equal sharing of electrons are known as non-polar molecules.
This is based on the difference in electronegativities
of Si, Al and Ti relative to oxygen.
It should be emphasized that the difference in electronegativities
, not the absolute electronegativity values, determines whether a covalent bond is polar or nonpolar.
Dipoles result when atoms with unequal electronegativities
are attached to each other in a chemical bond.
Allen prefers to think of electronegativities
as "configuration energies" that collectively represent a third dimension of the periodic table.