Calcium is the chemical element with the symbol Ca and atomic number 20. It has an atomic mass of 40.078 amu. Calcium is a soft grey alkaline earth metal. Calcium, with a specific mass of 1.55 g/cm3, is the lightest of the alkali earth metals. Chemically calcium is reactive and soft for a metal (though harder than lead, it can be cut with a knife with difficulty). It is a silvery metallic element that must be extracted by electrolysis from a fused salt like calcium chloride. In powdered form, the reaction with water is extremely rapid, as the increased surface area of the powder accelerates the reaction with the water. Many calcium salts are not soluble in water. When in solution, the calcium ion to the human taste varies remarkably, being reported as mildly salty, sour, "mineral like" or even "soothing". In human nutrition, soluble calcium salts may be added to tart juices without much effect to the average palate. Calcium occurs most commonly in sedimentary rocks in the minerals calcite, dolomite and gypsum.
Calcium compounds
- Calcium carbonate (CaCO3) used in manufacturing cement and mortar, lime, limestone (usually used in the steel industry); aids in production in the glass industry, also has chemical and optical uses as mineral specimens in toothpastes.
- Calcium hydroxide solution (Ca(OH)2) (also known as limewater) is used to detect the presence of carbon dioxide by being bubbled through a solution. It turns cloudy where CO2 is present.
- Calcium arsenate (Ca3(AsO4)2) is used in insecticides.
- Calcium carbide (CaC2) is used: to make acetylene gas (for use in acetylene torches for welding) and in the manufacturing of plastics.
- Calcium chloride (CaCl2) is used: in ice removal and dust control on dirt roads, in conditioner for concrete, as an additive in canned tomatoes, and to provide body for automobile tires.
- Calcium cyclamate (Ca(C6H11NHSO3)2) was used as a sweetening agent but is no longer permitted for use because of suspected cancer-causing properties.
- Calcium gluconate (Ca(C6H11O7)2) is used as a food additive and in vitamin pills.
- Calcium hypochlorite (Ca(OCl)2) is used: as a swimming pool desinfectant, as a bleaching agent, as an ingredient in deodorant, and in algaecide and fungicide.
- Calcium permanganate (Ca(MnO4)2) is used in liquid rocket propellant, textile production, as a water sterilizing agent and in dental procedures.
- Calcium phosphate (Ca3(PO4)2) is used as a supplement for animal feed, fertilizer, in commercial production for dough and yeast products, in the manufacture of glass, and in dental products.
- Calcium phosphide (Ca3P2) is used in fireworks, rodenticide, torpedoes and flares.
- Calcium stearate (Ca(C18H35O2)2) is used in the manufacture of wax crayons, cements, certain kinds of plastics and cosmetics, as a food additive, in the production of water resistant materials and in the production of paints.
- Calcium sulfate (CaSO4·2H2O) is used as common blackboard chalk, as well as, in its hemihydrate form being more well known as Plaster of Paris.
- Calcium tungstate (CaWO4) is used in luminous paints, fluorescent lights and in X-ray studies.
- Hydroxylapatite (Ca5(PO4)3(OH), but is usually written Ca10(PO4)6(OH)2) makes up seventy percent of bone. Also carbonated-calcium deficient hydroxylapatite is the main mineral of which dental enamel and dentin are comprised.
