What is "nitrogen"

Nitrogen \Ni`tro*gen\ (n[imac]"tr[-o]*j[e^]n), n. [L. nitrum natron + -gen: cf. F. nitrog[`e]ne. See Niter.] (Chem.) A colorless nonmetallic element of atomic number 7, tasteless and odorless, comprising four fifths of the atmosphere by volume in the form of molecular nitrogen ( N2). It is chemically very inert in the free state, and as such is incapable of supporting life (hence the name azote still used by French chemists); but it forms many important compounds, such as ammonia, nitric acid, the cyanides, etc, and is a constituent of all organized living tissues, animal or vegetable. Symbol N. Atomic weight 14.007. It was formerly regarded as a permanent noncondensible gas, but was liquefied in 1877 by Cailletet of Paris, and Pictet of Geneva, and boils at -195.8 [deg] C at atmospheric pressure. Liquid nitrogen is used as a refrigerant to store delicate materials, such as bacteria, cells, and other biological materials.

1794, from French nitrogène, coined 1790 by French chemist Jean Antoine Chaptal (1756-1832), from comb. form of Greek nitron "sodium carbonate" (see nitro-) + French gène "producing," from Greek -gen "giving birth to" (see -gen). The gas was identified in part by analysis of nitre. Earlier name (1772) was mephitic air, and Lavoisier called it azote (see azo-).

n. 1 (context uncountable English) A chemical element (''symbol'' N) with an atomic number of 7 and atomic weight of 14.0067. 2 (context uncountable English) Molecular nitrogen (N₂), a colorless, odorless gas at room temperature. 3 (context countable English) A specific nitrogen within a chemical formula, or a specific isotope of nitrogen

n. a common nonmetallic element that is normally a colorless odorless tasteless inert diatomic gas; constitutes 78 percent of the atmosphere by volume; a constituent of all living tissues [syn: N, atomic number 7]

Nitrogen is a chemical element with symbol N and atomic number 7. It is the lightest pnictogen, and at room temperature it is a transparent, odorless diatomic gas. Nitrogen is a common element in the universe, estimated at about seventh in total abundance in the Milky Way and the Solar System. On Earth, the element forms about 78% of Earth's atmosphere and is the most abundant uncombined element. The element nitrogen was discovered as a separable component of air by Scottish physician Daniel Rutherford in 1772.

Many industrially important compounds, such as ammonia, nitric acid, organic nitrates ( propellants and explosives), and cyanides, contain nitrogen. The extremely strong triple bond in elemental nitrogen (N≡N) dominates nitrogen chemistry, causing difficulty for both organisms and industry in converting the N into useful compounds, but at the same time causing release of large amounts of often useful energy when the compounds burn, explode, or decay back into nitrogen gas. Synthetically produced ammonia and nitrates are key industrial fertilizers, and fertilizer nitrates are key pollutants in the eutrophication of water systems.

Apart from its use in fertilizers and energy-stores, nitrogen is a constituent of organic compounds as diverse as Kevlar fabric and cyanoacrylate "super" glue. Nitrogen is a constituent of every major pharmacological drug class, including antibiotics. Many drugs are mimics or prodrugs of natural nitrogen-containing signal molecules: for example, the organic nitrates nitroglycerin and nitroprusside control blood pressure by metabolizing into nitric oxide. Plant alkaloids (often defense chemicals) contain nitrogen by definition, and many notable nitrogen-containing drugs, such as caffeine and morphine, are either alkaloids or synthetic mimics that act (as many plant alkaloids do) on receptors of animal neurotransmitters (for example, synthetic amphetamines).

Nitrogen occurs in all organisms, primarily in amino acids (and thus proteins), in the nucleic acids ( DNA and RNA) and in the energy transfer molecule adenosine triphosphate. The human body contains about 3% by mass of nitrogen, the fourth most abundant element in the body after oxygen, carbon, and hydrogen. The nitrogen cycle describes movement of the element from the air, into the biosphere and organic compounds, then back into the atmosphere.