Oxydation

Oxydation, more commonly written oxidation, is a chemical process in which a substance increases its oxidation state, typically by losing electrons. In redox chemistry, oxidation is paired with reduction, meaning that one species loses electrons while another gains them. Although the term historically arose from reactions with oxygen, oxidation does not require oxygen and can involve many electron acceptors, such as halogens, metal ions, or organic molecules.

In practical terms, oxidation encompasses a wide range of reactions. Common examples include the rusting of iron, where iron is oxidized in the presence of water and oxygen, and combustion, where a fuel reacts with an oxidant to release energy. Biological systems also rely on oxidation, most notably during cellular respiration, where energy is obtained through controlled oxidation of nutrients via electron transfer chains. In synthetic chemistry, oxidation refers to methods that introduce oxygen-containing groups or remove electrons, using reagents such as permanganates, chromates, or hydrogen peroxide.

Oxidation states are tracked via oxidation numbers, a bookkeeping method that helps chemists understand electron transfer in reactions. Oxidants are substances that accept electrons, while reductants donate them. Oxidation is often accompanied by changes in material properties, such as the formation of oxide layers on metals, which can either promote corrosion or protect surfaces through passivation.

Prevention and control are important in many contexts. Antioxidants, stabilizers, coatings, or inert atmospheres can slow or halt unwanted oxidation in foods, cosmetics, metals, and electronic components. The spelling oxydation appears as an alternative or historical variant of oxidation, but the concepts remain the same.