Nitrogen

Nitrogen is a nonmetal that forms a colorless, odorless gas under ordinary conditions. It makes up about 78% of Earth's air by volume. Its molecules contain two atoms joined by a strong triple bond, making the gas relatively unreactive. Nitrogen is also part of proteins and DNA in living things. Industry obtains it by separating it from air, either using special membranes or materials that trap other gases, or by cooling air to a liquid and separating its components by their different boiling points. Nitrogen gas helps keep packaged food fresh by replacing oxygen. Its compounds, including ammonia and nitrates, are important fertilizers that supply plants with nitrogen for growth.