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).

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