valencestate

Valence state, commonly referred to as oxidation state, is a formalism used in chemistry to describe the degree of oxidation of an atom within a chemical species. It provides a bookkeeping method for tracking electron transfer in redox reactions and aids in understanding bonding and reactivity in inorganic and coordination chemistry.

In most chemical contexts, oxidation states are represented by integers that can be positive, negative, or zero. The rules for assigning oxidation states include: the sum of the oxidation states of all atoms in a neutral molecule must be zero, and in an ion the sum must equal the ion’s charge. Fluorine is assigned an oxidation state of -1 in compounds, oxygen is typically -2 except in peroxides or when bonded to fluorine, hydrogen is usually +1 (except in hydrides where it is -1). Bonding in a compound is analyzed by allocating electrons to the more electronegative partner, which determines the oxidation state of each element.

Oxidation states are widely used to balance redox equations, predict possible reaction pathways, and assess electron counting in coordination complexes and organometallics. They are also helpful for understanding trends in the periodic table and for classifying elements by common oxidation states, such as the common +2, +3, and +6 states of transition metals.

It is important to note that oxidation states are a formalism rather than a precise account of electron density. In covalent compounds, the actual electron distribution may differ from the assigned states, and some elements exhibit a range of accessible oxidation states under different conditions. Related concepts include valence, formal charge, and redox potential.