Sodium is an abundant metallic element that is an important mineral for all living organisms. It is also widely used industrially to make an assortment of consumer goods. The soft metal also appears in an abundance of compounds, such as sodium chloride, better known as salt. It also exists in high concentrations in seawater, and it is among the 10 most abundant minerals in the Earth's crust.
In a pure form, sodium is a soft, silvery gray, highly reactive metal. It is usually stored in a nonreactive substance, as it oxidizes rapidly when exposed to air, quickly forming a thick coating. The element is also highly explosive when exposed to moisture and water, to the delight of many chemistry students. Since it is so reactive, it is usually found naturally in compounds with other elements. Many of these compounds, such as salt, are extremely stable and perfectly safe to handle. Others, like sodium hydroxide, need to be handled carefully as they can be hazardous.
On the periodic table of elements, sodium is identified with the symbol Na. This is a reference to a Latin word natrium, used to refer to a specific type of salt. Its atomic number is 11, placing it among other lightweight chemical elements, and it was first isolated in 1807 by Sir Humphrey Davy, an extremely active chemist who managed to identify and isolate a wide range of chemical elements. Davy achieved this isolation by passing an electric current through a compound of sodium to separate the elements.
Although Sir Davy certainly isolated the element, its existence was well understood before 1807. Humans have a long history with sodium and an assortment of its compounds. Since the element is so vital to healthy life, it is not surprising that sources such as sodium chloride have long been highly prized by humans. A wide assortment of other compounds were used around the house and in industrial manufacture for centuries before the element was fully understood.
The element is extremely abundant on Earth and it is heavily harvested and processed for manufacturing. Soaps, metal alloys, metal refining, and engines all rely heavily on sodium, and the metal is also used in lighting, chemistry, and numerous other applications. The pure form requires careful handling, since it is extremely caustic in the presence of even small amounts of moisture. It should be handled with tongs and used under close supervision.