Calcium

Calcium 40.078(4)   Ca 20 [Ar] 4s2 2,4,s [ ? ] Alkaline Earth Metal: Properties: Metallic Compounds: combined with phosphate to form hydroxylapatite, oxide (lime), carbonate, nitrate, sulfide, chloride, carbide, cyanamide, hypochlorite Uses: as a reducing agent in the extraction of other metals, such as uranium, zirconium, and thorium; as a deoxidizer, desulfurizer, or decarbonizer for various ferrous and nonferrous alloys; as an alloying agent used in the production of aluminium, beryllium, copper, lead, and magnesium alloys; in the making of cements and mortars to be used in construction; in the making of cheese, where calcium ions influence the activity of rennin in bringing about the coagulation of milk. Hazard: flammable

Calcium is the chemical element with the symbol Ca and atomic number 20.

Calcium is essential for life, particularly in cell physiology, where movement of the calcium ion Ca²⁺ into and out of the cytoplasm functions as a signal for many cellular processes, including neuromuscular contractions. It is also a major material used in mineralization of bones, teeth and shells.