Gordy’s electrostatic scale of electronegativity revisited

Abstract

Gordy identified electronegativity of an atom with the electrostatic potential felt by one of its valence electrons and suggested an ansatz, χ = Z eff/ r cov where χ is the electronegativity, Z eff is the effective nuclear charge and r cov is the radial distance equal to atom’s single bond covalent radius. In this report we have elucidated that the use of covalent radius in evaluating the electronegativity, ( χ), of atoms through Gordy’s formula, χ = Z eff/ r cov, is not justified. Armed with this knowledge and relying upon the electronegativity equalization principle, we have argued that the most probable radius (Slater radius), and not the covalent radius, is the fundamental size descriptor of atoms in mathematical formulation of electronegativity property of atoms. We have also suggested that the electronegativity, χ, is not equal to Z eff/ r according to Gordy’s original formula rather it is proportional to Z eff/ r and the new electronegativity ansatz is χ = [ a( Z eff/ r) + b], where a and b are constants and r is the Slater (most probable) radius of atoms. We have taken care so that the electronegativity is evaluated in proper unit i.e. energy unit. We have computed the electronegativity of 103 elements of the periodic table through the new suggested ansatz and using Slater radii and effective nuclear charge computed by us. The evaluated new electronegativities are found to satisfy the sine qua non of a reasonable scale of electronegativity by exhibiting periodicity of periods and groups, and observing silicon rule and correlating many physico-chemical properties of elements. The intrinsic inertness of Hg atom is revealed in the present scale.