Electronegativity: A Mnemonic Number Code for an Atom

Abstract

An attempt is made to substantiate that, electronegativity expressed as Hellman-Feynman force(Force by Nucleus on electron) or Ehrenfest force(Force by electron on Nucleus) will be accurate and absolute. The concept of Hellman-Feynman force as an equivalence of Born-Oppenheimer approximated energy for di-atomic system and Hartree-Fock force as an equivalence of Hartree-Fock approximated energy for polyatomic system have been critically analyzed. An extended theory of Electronegativity based on Force concept is established. Electronegativity values computed for various elements using Hellmann-Feynman force exerted on the nuclei and the Ehrenfest force exerted on the electron density are presented. I. INTRODUCTION All models of electronegativity are theorized by individual's intuition. The qualitative understanding of electronegativity is not up to the mark. Universal acceptance on the common agreement of the all models till to 2019 A.D seems impossible. Force model of electronegativity was defined first by AL Allred and EG Rochow[1] with help of electrostatic field. According to this definition, electronegativity is equal to Coulomb force of attraction between the nucleus and an electron at the covalent radius. 2 * 2 AR e Z r c º (1) Where Z*=Zσ, r is covalent radius for the atom(considering smaller value as well as outer radial maxima). The Coulomb force is a measure of power of an atom in a molecule that drags electron towards nucleus. Therefore, electronegativity is an absolute one. AR c dimension is not straight forward as it is evaluated through eq. 1. The quantity Z * /r 2 was calculated through Pauling's work and Slater rules[2,3]. Pauling's Scale and Allred-Rochow scale can be made to coincide by expressing the electronegativity from the electrostatic approach as the linear function of Z * /r 2 .Here mean radius is expressed in picometer. 3590(/ 2) 0.744 AR z r     EQ (2) WHERE 3590 AND 0.744 ARE NUMERICAL CONSTANTS.