The most common metallic element in the body, calcium is a vital nutrient. It acts as a fuel for cells, and it is needed to form bones and teeth. It is also essential in the formation of a healthy electrolyte balance within the body.
calcium metal is a silvery white metal that is very soft and ductile. It is extremely reactive, however, and reacts rapidly with oxygen to form a grey oxide coating. This coating is more resistant to oxidation than magnesium’s, but it still dissolves in air under high temperatures.
It is a good conductor of electricity, but it has a low melting point. This makes it difficult to produce pure calcium from its compounds. Most of the commercially produced calcium comes from the aluminothermic reduction process, but it can also be made by electrolysis of CaCO3.
Like other alkali earth metals, calcium is nontoxic. Its chemical reactivity, however, means that it needs to be handled carefully. In contact with water it decomposes to release hydrogen, forming calcium hydroxide, Ca(OH)2. This is used to make acetylene gas in carbide lamps.
It is also used in the manufacture of refractory materials such as castable refractories and fireclay. It can be alloyed with aluminium, beryllium, copper, lead and magnesium to make various special-purpose alloys. It is also used in vacuum tubes as a “getter”, which combines with and removes trace gases from the inside of the tube. It is also found in some radioactive minerals such as thorium, uranium and zirconium, where it is used to purify them.