Sodium has an atomic number of 11 and atomic mass of 22.989769 .It's a soft metal, reactive and with a low melting point, with a relative density of 0,97 at 20ºC (68ºF). Sodium reacts quickly with water, and also with snow and ice, to produce sodium hydroxide and hydrogen. Although sodium is the sixth most abundant element on earth and comprises about 2.6% of the earth's crust, it is a very reactive element and is never found free in nature. Pure sodium was first isolated by Sir Humphry Davy in 1807 through the electrolysis of caustic soda (NaOH). The most common compound of sodium is sodium chloride (common salt). It is added to food and used to de-ice roads in winter. It is also used as a feedstock for the chemical industry. Sodium carbonate (washing soda) is also a useful sodium salt. Sodium is a Alkali Metal.