Affixes

In oxyacetylene and oxyhydrogen the form denotes welding or cutting techniques using a very hot flame produced by mixing acetylene or hydrogen with oxygen; oxyhaemoglobin is a bright red substance formed by the combination of haemoglobin with oxygen, present in oxygenated blood; an oxyacid is an inorganic acid whose molecules contain oxygen, such as sulphuric or nitric acid; an oxide is a binary compound of oxygen with another element or group; oxidation originally referred to a chemical combination with oxygen, but is now usually understood as a reaction by which electrons are lost from an atom.

The forms oxo‑ and oxa‑ have specific meanings in the systematic rules for naming chemical compounds; the former refers to the presence of a carbonyl group, ==CO, anywhere in an organic molecule: oxodecanoic acid, 3-oxohexanal; the latter to an oxygen atom appearing in a heterocyclic molecule, assumed to replace a —CH₂— group: 6-oxa-3-thiadecanenitrile.

See also deoxy‑, ethoxy‑, and methoxy‑.