Nitrogen is the fifth most abundant element in the universe, and makes up 78 percent of the Earth's atmosphere. Nitrogen is a gas at room temperature and has an atomic number of seven. Nitrogen has a wide number of practical applications, including the production of ammonia and in the oil industry, where it is used to bring crude oil to the surface.
Nitrogen is a mostly inert, colorless, odorless non-metallic gas discovered in 1772 by Scottish physician Daniel Rutherford. Nitrogen molecules are mainly found in air. Nitrogen is an essential element in all living materials, and is present in DNA.
Although nitrogen is abundant on earth, it is inaccessible to many organisms because most nitrogen atoms are bonded to other nitrogen atoms. The process of nitrogen fixation occurs to convert bonded nitrogen in the atmosphere into single atoms of free nitrogen that can be utilized in other chemical reactions, such as the formation of proteins. Nitrogen fixation is an important part of the nitrogen cycle, which creates usable nitrogen and replaces nitrogen taken from the atmosphere.
Liquid nitrogen is often used as a refrigerant. In this form, nitrogen can quickly freeze food for transportation, and can also preserve bodies or biological material.