Time：2022-12-07
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Calcium was named after the Latin term calx meaning lime, and is a reactive silvery metallic element found in Group 2 of the periodic table. It was first isolated in 1808 in England when Sir Humphry Davy electrolyzed a mixture of lime and mercuric oxide.
calcium is in fact classed as a minor metal. Say ‘calcium’ and a metallic substance does not immediately spring to mind, rather a chalky powdery rock or possibly a bottle of milk.
Calcium is, however, a metal in its pure form, though rarely seen in this state due to its instability. In air, calcium decomposes rapidly into calcium hydroxide and calcium carbonate.
Although calcium is the fifth most abundant element (and 3rd most abundant metal) in the earth’s crust, present at a level of about 3% in the oceans and soil, it is never found free in nature. Calcium easily forms compounds by reacting with not only air but also with water and acid (on contact with water or acid, hydrogen gas is made in a fairly controlled manner, in comparison to the other alkali metals).
Today metallic calcium is obtained through the electrolysis of a fused salt such as calcium chloride. Once exposed to air, elemental calcium rapidly forms a grey-white oxide and nitride coating. Unlike magnesium, calcium is quite difficult to ignite, but once lit, it burns with a brilliant high-intensity red flame. Also, calcium metal is obtained by the Aluminothermic process of metallic aluminum to reduce lime under vacuum and high temperature, and then distillation to obtain calcium which is mainstream method currently.
Due to its high reactivity with common materials, there is very little demand for metallic calcium.
Calcium metal is used as a reducing agent in preparing other metals such as thorium and uranium. It is also used as an alloying agent for aluminium, beryllium, copper, lead and magnesium alloys.
In modern industry, calcium metal is used as:
- a reducing agent in preparing other metals such as chromium, thorium and uranium,