thio-
Sulphur
Greek theion, sulphur.
The form is used in chemistry to indicate the replacement of oxygen in a molecule by sulphur: a thiosulphate (US thiosulfate) is a salt containing the anion S2O32‑, equivalent to a sulphate with one oxygen atom replaced by sulphur; thiourea is the sulphur analogue of urea, SC(NH2)2, used in photography and in making synthetic resins; a thiocyanate is a salt containing the anion SCN‑; the adjective thionyl denotes the divalent radical ==SO.
Copyright © Michael Quinion 2008–. All rights reserved. Your comments are very welcome.