Cover Feature: The Chemical Bond: When Atom Size Instead of Electronegativity Difference Determines Trend in Bond Strength (Chem. Eur. J. 63/2021).

Keywords: Bond energy; Bond theory; Density functional calculations; Main group elements; Thermochemistry EN Bond energy Bond theory Density functional calculations Main group elements Thermochemistry 15561 15561 1 11/16/21 20211111 NES 211111 B Atom size, b I B not b i B electronegativity difference b , determines C-X bond strength, which weakens from X=F to I. In their Communication (DOI: 10.1002/chem.202103544), M. Bickelhaupt et al. reveal that, as the atom size increases, it is the increase in steric Pauli repulsion that weakens the C-X bond, and not the weakening of the orbital interaction (which, in fact, strengthens it!), as is traditionally considered in the electronegativity model. Bond energy, Bond theory, Thermochemistry, Density functional calculations, Main group elements. [Extracted from the article]