Sodium

Sodium, chemical element, symbol Na; for physical constants see Periodic Table. Sodium is the sixth most abundant element on earth. The free element was obtained by Sir Humphry Davy in 1807 by electrolysis of caustic soda (sodium hydroxide). It is found most commonly as common salt, but it occurs in many other minerals. It is obtained commercially by the electrolysis of dry fused sodium chloride. Sodium is a silvery-white, reactive metal, the most abundant of the alkali metal group. It is essential in human and animal nutrition. Sodium and its compounds are used in the paper, glass, soap, textile, petroleum, chemical, and metal industries. It is the cheapest of all metals.