Oxidationsstatus

Oxidationsstatus, commonly referred to as oxidation state or oxidation number, is a formal bookkeeping method used in chemistry to describe the oxidation level of an atom within a molecule or ion. It assigns integers to atoms so that the sum of all oxidation states in a neutral compound is zero, and in a polyatomic ion equals the ion’s charge. The concept helps track electron transfer in redox (oxidation–reduction) processes and provides a convenient framework for balancing redox equations.

Rules for assigning oxidation states are rules-based and aim to be unambiguous for typical compounds. An element in its standard state has oxidation status 0. In simple ions, the oxidation state equals the ion’s charge. Fluorine is always −1 in compounds; hydrogen is normally +1 (except in metal hydrides, where it is −1); oxygen is normally −2 (except in peroxides or with fluorine). The sum of oxidation states in a neutral molecule is 0; in a polyatomic ion it equals the ion’s overall charge. In covalent bonds, electrons are assigned to the more electronegative atom for the purpose of oxidation-state calculation, and formal charges are not the same as real electron distribution.

Common and illustrative oxidation states include carbon from −4 to +4, nitrogen from −3 to +5, and transition metals that can adopt multiple states (for example Fe2+ and Fe3+, Mn2+ or MnO4− where Mn is +7). The oxidation state concept is widely used in redox titrations, electrochemistry, inorganic synthesis, and biochemistry to understand and balance electron transfer.

Limitations should be noted: oxidation states are a formalism and do not necessarily reflect actual electron density or dative bonding in all situations, especially in highly covalent or mixed-valence systems.