Periodic Table ~ calcium ~ Element ~ CAS 7440-70-2

calcium

Name	calcium
Symbol	Ca
Atomic Weight	40.078
Atomic Number	20
CAS ID	7440-70-2
Group Number	2
Group Name	Alkaline Earth Metal
Period Number	4
Origin of Name	Latin, calx ="lime."
Year Discovered	1808
Discovery Credits	Isolated by Sir Humphry Davy in London, UK.
Class	Metallic
Color	Silvery White
Standard State	Solid at 77 F & 298 K
Description	Silvery white, relatively soft metal obtained from fused calcium chloride by electrolysis. Protected by oxide/nitride film and can be worked as a metal. Used in alloys and in manufacture of Zr, Th, U, and rare earth metals. Lime (CaO) used in metallurgy, water treatment, chemicals, building, etc. Diagnostic tests: Infusible calcium minerals glow with exaggerated incandescence in the flame test (along with Sr, Mg, Zr, Zn, Ce - the "lime light effect"). Sometimes, a orange red flame color may be observed if interfering Sr or Na is not present (try calcite moistened with HCl). In solution, (NH₄)₂CO₃ will precipitate calcium as an insoluble carbonate (along with Ba and Sr). Dissolve the precipitate in HCl and try the flame test for Ca (orange red), Ba (green), or Sr (purple red).