Sodium is a silvery white metal which oxidises rapidly in air and it is therefore stored under oil. It has a melting point less than the boiling point of water - passing hot water in coils around sodium is sufficient to melt it.
Sodium was first isolated by the British scientist Humphry Davy (1778-1829) in 1807 by passing an electric current through molten sodium hydroxide:
4NaOH (sodium hydroxide) -> 2H2O (water) + O2 (oxygen) + 4Na (sodium)
He inserted electrodes from a battery in a fused mixture of sodium hydroxide and found that globules of silvery metal (sodium) collected at the battery's negative electrode. The chemical symbol Na is from natrium the Latin word for salt (sodium chloride).
Sodium produces a bright yellow flame. Low pressure sodium lamps, such as those used in some parking lots, emit a yellow (wavelength 589 nm) light. The metal is used by the chemical industry in the production of dyes, including in the manufacture of the indigo dye used to colour blue jeans.