Oxidation state (OS) is a simple numerical attribute of an atom in a compound, which aids the systematic descriptive chemistry of the elements, scales trends in properties, and tracks key chemistry changes in reactions. Lacking a comprehensive definition, OS has so far been defined via algorithms for its calculation or with postulated values. This document provides a definition of OS based on ionic approximation of chemical bonds. Associated with the definition’s underlying principle of bond-electron allegiance, two general algorithms are outlined for OS determination in a molecule, ion, or a solid, described by a Lewis formula or a bond graph. Typical origins of ambiguous OS values are pointed out, and the relationship between OS and the d-electron configuration of transition metals is commented on.
Comments by 31 May 2016.