Appearance
Sodium is a soft, silvery white metal which oxidises rapidly on exposure to air.

Source
Sodium is the sixth most abundant element on Earth, and comprises 2.6% of the Earth's crust. The most common compound is Sodium Chloride (common salt), but is is also found in many minerals such as Cryolite, Zeolite and Sodalite. It is never found free in nature, due to its great reactivity. Sodium is obtained commercially by the electrolysis of dry fused Sodium Chloride.

Uses
Metallic Sodium is used in the manufacture of sodamide and esters, and in the preparation of certain organic compounds. Other uses of the metal include descaling and purifying metals, and alloy formation. One alloy of Sodium and Potassium is an important heat transfer agent. Sodium compounds are important in many industries, including paper, glass, soap, textile, petroleum and metal. Salt (Sodium chloride) is also of vital nutritional importance, although too much salt in the diet has been linked to high blood pressure.

General Information
Sodium is very reactive, and should be handled with care. It floats on water, decomposing it with the evolution of Hydrogen and the formation of Sodium hydroxide. It may or may not ignite spontaneously on the water, depending on the amount of metal in contact with the water. It normally does not ignite in air at temperatures below 115K.