Calcium

‘Calcium’ is the name given by Sir Humphry Davy to the metal that he first isolated by electrolysis in 1808. It is derived from Latin calx (lime) which most likely came from Greek χάλιξ (pebble, limestone). The English word ‘chalk’ is also derived from calx. My inner folk etymologist has successfully linked chalk with ‘calculation’ (via the blackboard, of course), but it seems that the connection is a bit older than blackboard: Latin calculus is simply a ‘little pebble’ used in calculations on an abacus. (Latin for chalk is not calx but creta, thus Cretaceous period.)

Not everything that starts with ‘calcium’ is a calcium compound. For instance, this chapter of Invitrogen’s Guide to Fluorescent Probes and Labeling Technologies contains a section on Calcium Green, Calcium Yellow, Calcium Orange and Calcium Crimson indicators. These compounds, upon binding Ca²⁺, exhibit a strong increase in fluorescence emission intensity. I suppose the corresponding fluorescent complexes then should be named something like ‘calcium Calcium Crimson’ and so on.