Symmetry, hybridization and bonding in molecules

Abstract

Brief historical review of the applications of symmetry arguments in interpreting the electronic and geometric structures of molecules is given. The hybridization of atomic orbitals is thoroughly discussed. It was shown that hybridization model describes directional features of covalent bonding and a number of other properties which are not directly related otherwise. This versatility in rationalizing a large number of experimental data of different kinds and a high interpretative power give to the model some semblance of truth. The model's apparently good reflection of molecular properties could be traced to the fact that hybrids conform with the local symmetry of an atom in a molecular environment. An analogy between the hybridization model and crystal field theory is found. The epistemological role of the hybridization is stressed. It provides a bridge between the most elementary first principles of quantum mechanics and the concept of a chemical bond, which is a basic tenet of the phenomenological theory of molecules.