Using the centre-of-mass of localized electron pairs to quantify electronegativity

Abstract

Localized electron pair densities are explored with the purpose of developing a relationship between properties of the electron pair centre-of-mass and atomic electronegativities. These electron pair centre-of-mass densities are determined for the localized molecular orbital representing the A–H bond in a compound AHn (where n = 1–4) for each of the first and second row atoms with available valence sites. By analyzing the topography of these densities, we observe the migration of the electron pair as the electronegativity of atom A changes. We demonstrate strong linear correlations between features of these centre-of-mass densities and various empirically based electronegativity scales, all of which are defined in significantly different ways. Based on strong agreement with past electronegativity scales, we propose the use of localized electron pair centre-of-mass densities as a simple and intuitive theoretical model for electronegativity. We have presented our own electronegativity scale, employing Pauling units as is common amongst many existing scales.