Chemistry - Calcium



  • Calcium is a soft grayish-yellow alkaline element found largely in the Earth’s crust.

  • Calcium’s symbol is “Ca” and atomic number is “20.”

  • Free calcium hardly exists in nature, as it is highly reactive.

  • Calcium is produced usually in supernova nucleosynthesis.

Salient Features of Calcium

  • Calcium is one of the most abundant metals by mass found in many animals.

  • Calcium is a very important constituent of teeth, bone, and shells.

  • Calcium carbonate and calcium citrate are the major dietary supplements required for a good health.

  • World Health Organization (WHO) listed calcium as the Essential Medicines.

  • In comparison to other metals, the calcium ion and most of the other calcium compounds have low toxicity.

  • If calcium comes in contact with water or acid, it reacts with them and becomes hazardous.

  • If calcium comes in contact with air, it reacts swiftly and forms a gray-white coating of calcium nitride and calcium oxide.

  • Most of the calcium salts are normally colorless.

  • When calcium burnt, the color of its flame appears brick red (see the image given below).

Calcium Component
  • Calcium metal has comparatively a higher electrical resistivity than aluminum or copper.


  • Calcium occurs usually in sedimentary rocks.

  • The minerals (sedimentary) in which calcium found are calcite, dolomite, and gypsum.

  • Calcium also found in igneous and metamorphic rocks mostly in the silicate minerals, such as amphiboles, plagioclases, pyroxenes, and garnets.

  • Calcium also found in many of the food products namely dairy products, almonds, hazelnuts, soy beans, broccoli, dandelion leaves, figs, and in many more.

Compounds of Calcium

  • Calcium oxide - CaO

  • Calcium hydroxide - Ca(OH)2

  • Calcium chloride - CaCl2

  • Calcium hypochlorite (Bleaching powder) - Ca(ClO)2

  • Calcium phosphate - Ca3(PO4)2

Uses of Calcium

  • Calcium has wide range of usage, significant of them are −

    • Calcium carbonate (CaCO3) is used in manufacturing cement.

    • Calcium carbonate (CaCO3) is also used in making toothpaste.

    • In insecticides, calcium arsenate (Ca3(AsO4)2) is used.

    • Calcium chloride (CaCl2) is used in ice removal as well as in dust control.

    • Calcium citrate (Ca3(C6H5O7)2) is commonly used as food preservative.

    • Calcium gluconate (Ca(C6H11O7)2) is used frequently as a food additive as well as in vitamin pills.

    • Calcium hypochlorite (Ca(OCl)2) is generally used as a swimming pool disinfectant, as a bleaching agent.