Chapter 3 - Covalent Bonding and Molecular Structure

Abstract

When atoms combine to form compounds, atomic orbitals interact so that electron density is shared with the formation of covalent bonds. The two ways in which this is viewed are expressed by the valence bond (VB) and molecular orbital (MO) methods. In VB theory, the atomic orbitals essentially keep their character and interact by overlapping. In MO theory, the orbitals essentially lose their character as orbitals form that include multiple atoms. Orbitals may form hybrids that have directional properties that differ from those of atomic orbitals. The shapes and directional nature of orbitals give rise to the overall structures of molecules and ions. Hybrid orbitals generally form in such a way that repulsion between electron pairs is minimized. Structures can be characterized in terms of the symmetry elements (rotation axes, mirror planes, center of symmetry) that the structure possesses.