Nitrogen, or N2, is a diatomic gas which comprises 78 percent of the earth's atmosphere. In addition to air, nitrogen is found in the protein matter of all life forms, in some natural gas-hydrocarbon deposits, and in many organic and inorganic compounds.

Colorless, odorless, tasteless, and nontoxic, nitrogen exists as a non-flammable gas at atmospheric temperatures and pressures. A specific gravity of .9669 makes nitrogen slightly lighter than air. When cooled to its boiling point of -320°F, nitrogen becomes a colorless liquid which can, in turn, be compressed into a colorless, crystalline solid. It is only slightly soluble in water and most other liquids, and is a poor conductor of heat and electricity.

Most uses of gaseous nitrogen depend on its inert characteristics. At high temperatures and pressures, however, it will combine with some reactive metals (such as lithium and magnesium) to form nitrides, as well as with some gaseous elements such as hydrogen and oxygen.