Valence bond theory is one of two main theories (the other being molecular orbital theory) that is used to explain bonding in molecules. Valence bond theory explains bonding by describing the interactions of atomic orbitals on individual atoms as they come together to form chemical bonds. The basic idea is that orbitals with the right shapes to overlap strongly with each other will form the strongest chemical bonds. Today, valence bond theory’s description of chemical bonding based on atomic orbitals has become less popular in favor of molecular orbital theory.