Electronegativity based on the simple bond charge model

A single physical interpretation of the various electronegativity scales of Pauling, Mulliken and Gordy is suggested, based on the simple bond charge (SBC) model of Parr and Borkman for the covalent bond. With a charge partition determined from vibrational frequencies, the SBC model is shown to account for the covalent bond energy in single-bonded homonuclear diatomic molecules and diamond-type crystals. The binding energy to the atom of a bond-electron in the single-bonded homonuclear diatomic molecules agrees with Mulliken's electroaffinity, and provides a definition for electronegativity. Gordy's empirical relation between the bond-stretching force constant and electronegativity is explained. It is then suggested that the physical effect underlying Pauling's thermochemical formula for electronagativity is the location of the bond charge in the heteronuclear molecule. The deviation of Pauling's formula from experiment in the case of the alkali hydrides can then be explained.