Stannous

Part of speech: adjective

Definitions

1. Containing tin with a chemical valence of two, as in compounds like stannous chloride
2. Relating to or composed of tin in its divalent form, where each tin atom carries a charge of +2
3. Designating chemical compounds or solutions in which tin exists in the +2 oxidation state rather than the +4 state

Etymology: "Stannous" is a plain chemical coinage: it combines "stann-", from Latin "stannum" (tin), with the English suffix "-ous," which marks a lower oxidation state of an element. Stannous compounds contain tin in its +2 state, so stannous chloride is the familiar tin(II) chloride. The Latin "stannum" itself is the older name for tin, and the chemical vocabulary built on it is a useful reminder of how chemists once labelled elements by their Latin names. The paired "-ous" and "-ic" endings, as in stannous and stannic, were a way of distinguishing two valences of the same metal, so the adjective is best understood as a technical label rather than a word with a story of everyday use.

Synonyms: tin-containing