kalciumin

Kalciumin, known in English as calcium (Ca), is a chemical element with atomic number 20. It is a soft, silvery-white metal in the alkaline earth family and is highly reactive in air and water. Calcium is the fifth most abundant element by mass in the Earth's crust.

Biologically, calcium is essential for living organisms. In humans, about 99% of body calcium is stored in bones and teeth, where it supports structure. It also plays key roles in muscle contraction, nerve function, and blood clotting. The recommended intake is achieved through dairy products, leafy greens, and fortified foods.

Chemically, calcium forms oxides and hydroxides upon heating and readily reacts with water to produce calcium hydroxide and hydrogen gas. It is typically produced and stored under protective conditions due to its reactivity.

Calcium occurs in many minerals, notably calcite and limestone (calcium carbonate), gypsum (calcium sulfate), and fluorite (calcium fluoride). Major commercial sources include limestone and other carbonate rocks.

Industrial uses include deoxidizing and alloying steel, producing cement and lime, and supplying calcium compounds for agriculture and nutrition. Calcium carbonate and calcium citrate are common dietary supplements.

Commercial calcium is produced mainly by electrolysis of molten calcium chloride (the Downs process). The most abundant naturally occurring isotope is calcium-40; several other stable isotopes are present in smaller amounts.

Kalciumin has a long history in science and industry, and its chemistry intersects with geology, biology, and medicine.