Hapettumisluvun

Hapettumisluvun, also known as the oxidation state or oxidation number, is a bookkeeping concept used in chemistry to track the hypothetical charge that an atom would have if all bonds to atoms of different elements were 100% ionic. It is a theoretical value assigned to an atom in a molecule or ion. The sum of the oxidation numbers of all atoms in a neutral molecule is zero. For a polyatomic ion, the sum of the oxidation numbers equals the charge of the ion.

There are a set of rules used to assign oxidation numbers. For example, elements in their elemental form have an oxidation number of zero. Alkali metals (Group 1) and alkaline earth metals (Group 2) typically have oxidation numbers of +1 and +2, respectively, in their compounds. Fluorine almost always has an oxidation number of -1. Oxygen usually has an oxidation number of -2, except in peroxides where it is -1, or when bonded to fluorine. Hydrogen typically has an oxidation number of +1 when bonded to nonmetals and -1 when bonded to metals.

Hapettumisluvun is a crucial tool for understanding and predicting the outcome of redox (reduction-oxidation) reactions, where electrons are transferred between species. Changes in oxidation numbers indicate which atoms are oxidized (lose electrons, oxidation number increases) and which are reduced (gain electrons, oxidation number decreases). This concept simplifies the analysis of complex chemical transformations.