Electronegativities, electrostatic potentials and covalent radii

Two different formulations of electronegativity are discussed and briefly r eviewed; one focuses upon the atom in a molecule, while the other is in ter ms of the chemical potential. Our analysis emphasizes the need for the latt er approach to take account of the external potential. We also examine two proposed procedures for approximating empirical covalent radii, as the radi al distances at which an atom's electrostatic potential V(r) equals (a) its ionization energy I, and (b) its chemical potential as given by 0.5(I + A) , where A is the electron affinity. Effective nuclear charges are computed for both distances for a group of 16 atoms. (C) 2001 Elsevier Science B.V. All rights reserved.