magnesium

Name magnesium
Symbol Mg
Atomic Weight 24.3050
Atomic Number 12
CAS ID 7439-95-4
Group Number 2
Group Name Alkaline earth metal
Period Number 3
Origin of Name Greek, "Magnesia" a district in Thessaly.
Year Discovered 1755
Discovery Credits Recognized by Joseph Black at Edinburgh, Scotland. Isolated by Sir Humphry Davy in 1808.
Class Metallic
Color Silvery White
Standard State Solid at 77 F & 298 K
Description Silvery white, lustrous, relatively soft metal. Obtained by electrolysis of fused MgCl2. Burns in air and reacts with hot water. Used as bulk metal and in lightweight alloys with magnesium for engines, also as a sacrificial electrode to protect other metals.

Diagnostic tests: 
Moistened, after heating, with cobalt nitrate (CoNO3)and again ignited, a pink color is obtained from some infusible compounds of magnesium. 
Infusible magnesium minerals glow with exaggerated incandescence in the flame test (along with Sr, Ca, Zr, Zn, Ce - the "lime light effect").
In solution, (NH4)2SO4 and (NH4)2C2O4 will remove Ca and Ba as a precipitate. Decant the solution and add NH4OH and Na2HPO4. A white precipitate (MgNH4PO4) shows the presence of magnesium.

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