Covalent Bonding Theories

Aspects of covalent and ionic bonding are discussed. Common terms, such as valence, oxidation state, and formal charge, are defined; the rules for determination of oxidation states are given. The electron dot theory of Lewis and its applications and problems are described. The shapes of species predicted by valence shell electron pair repulsion theory and the ligand close packing model are discussed. Valence bond theory is introduced in its classical or Pauling version and its modern, more quantitative approach. The development of molecular orbital theory and its application to diatomic, triatomic, and hypervalent species are described. The bonding in methane is developed in terms of both theories. The coverage of these topics includes references published through to mid-2021.