Chemical element of atomic number 20. It is the fifth element and the third more abundant metal in the terrestrial crust. The metal is trimorfo, harder than sodium, but softer than aluminum. Like beryllium and the aluminum, but unlike alkaline metals, noncause burns on the skin. He is less reactive chemically than alkaline metals. The distribution of calcium is very ample; one is in almost all the terrestrial areas of the world. This element is essential for the life of the plants and animal, since he is present in the skeleton of the animal, the teeth, and n the housing of eggs, in the chorale and many grounds. The calcium forms a film of oxide and nitride in the air, protects which it of a follow-on attack. Burning fire in the air to lifted temperature to take place nitride mainly. http://img.archiexpo.com/images_ae/2ai/save-En.gif
