Calcium (Ca), chemical element, one of the alkaline-earth metals of Group 2 (IIa) of the periodic table. It is the most abundant metallic element in the human body and the fifth most abundant element in Earth’s crust. Continue reading from Encyclopedia Britannica
Lime (calcium oxide, CaO) was the useful material obtained by heating limestone and used for centuries to make plaster and mortar. Antoine Lavoisier classified it as an ‘earth’ because it seemed impossible to reduce it further, but he suspected it was the oxide of an unknown element. In 1808, Humphry Davy tried to reduce moist lime by electrolysis, just as he had done with sodium and potassium, but he was not successful. So he tried a mixture of lime and mercury oxide and while this produced an amalgam of calcium and mercury, it was not enough to confirm that he’d obtained a new element. (Jöns Jacob Berzelius had conducted a similar experiment and also obtained the amalgam.) Davy tried using more lime in the mixture and produced more of the amalgam from which he distilled off the mercury leaving just calcium. Continue reading from Royal Society of Chemistry
Calcium is the 5th most abundant element in the Earth's crust, present at a level of about 3 percent in the oceans and soil. The only metals more abundant in the crust are iron and aluminum. Calcium is also abundant on the Moon. It is present at about 70 parts per million by weight in the solar system. Natural calcium is a mixture of six isotopes, with the most abundant (97 percent) being calcium-40.
Dairy products and grains are the primary sources of dietary calcium, accounting or about three-quarters of dietary intake. Other sources of calcium include protein-rich foods, vegetables, and fruits.
The element name "calcium" comes from the Latin word "calcis" or "calx" meaning "lime". In addition to occurrence in lime (calcium carbonate), calcium is found in the minerals gypsum (calcium sulfate) and fluorite (calcium fluoride).
Though calcium has been known for thousands of years, it was not purified as an element until 1808 by Sir Humphry Davy of England. Thus, Davy is considered to be the discoverer of calcium. Continue reading from ThoughtCo
