Electronegativity is the power of an atom attracting electron to itself in a molecule. It is a basic concept in chemistry. Pauling proposed the first electronegativity scale and after then many electronegativity scales were proposed. It is only on the basis of density functional theory that the concept and electronegativity principle were precisely proved theoretically. In recent decades, there have been some important developments of the electronegativity theory. Applying the electronegativity equalization model or method, one can rapidly calculate the charge distribution of a large molecule and then calculate the related properties, even molecular structure and reactivity indexes. The usual electronegativity equalization method divides a molecule only to atomic regions its accuracy and application are limited although it is simple and intuitive. Atom-bond electronegativity equalization method divides a molecule into not only atomic regions but also bond and lone-pair regions so that it can rapidly and accurately calculate molecular charge distribution and other properties, and recently it is also applied to develop a new generation of polarizable force field. Contents
1 Introduction
2 Electronegativity
2.1 Classical electronegativity scales
2.2 Modern electronegativity ideas
3 Electronegativity in density functional theory and related physical quantities
3.1 The first-order derivatives: chemical potential μ and electron density ρ
3.2 The second-order derivatives: global hardness, local hardness and local softness, fukui function
3.3 Electronegativity equalization principle
4 Modern electronegativity equalization method (EEM)
4.1 Mortier electronegativity equalization method (EEM)
4.2 Atom-bond electronegativity equalization method (ABEEM)
5 Conclusion