Nitrogen ( /ˈnaɪtrɵdʒɨn/ ny-trə-jin) is a chemical element that has the symbol N, atomic number of 7 and atomic mass 14.00674 u. Elemental nitrogen is a colorless, odorless, tasteless, and mostly inert diatomic gas at standard conditions, constituting 78.08% by volume of Earth's atmosphere. 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 bond? in elemental nitrogen dominates nitrogen chemistry, causing difficulty for both organisms and industry in breaking the bond? to convert the N2 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.

Nitrogen occurs in all living organisms, and the nitrogen cycle describes movement of the element from the air into the biosphere and organic compounds, then back into the atmosphere. Synthetically produced nitrates are key ingredients of industrial fertilizers, and also key pollutants in causing the eutrophication of water systems. Nitrogen is a constituent element of amino acids and thus of proteins and nucleic acids (DNA and RNA). It resides in the chemical structure of almost all neurotransmitters, and is a defining component of alkaloids, biological molecules produced by many organisms. The human body contains about 3% by weight of nitrogen, a larger fraction than all elements save oxygen, carbon, and hydrogen. Wikipedia, Nitrogen (external link)

Nitrogen is formally considered to have been discovered by Daniel Rutherford? in 1772, who called it noxious air or fixed air. The fact that there was an element of air that does not support combustion was clear to Rutherford. Nitrogen was also studied at about the same time by Carl Wilhelm Scheele?, Henry Cavendish?, and Joseph Priestley?, who referred to it as burnt air or phlogisticated air. Nitrogen gas was inert enough that Antoine Lavoisier? referred to it as "mephitic air" or azote?, from the Greek word ἄζωτος (azotos) meaning "lifeless". In it, animals died and flames were extinguished. Lavoisier's name for nitrogen is used in many languages (French, Polish, Russian, etc.) and still remains in English in the common names of many compounds, such as hydrazine? and compounds of the azide ion.

The English word nitrogen (1794) entered the language from the French nitrogène, coined in 1790 by French chemist Jean-Antoine Chaptal? (1756–1832), from "nitre" + Fr. gène "producing" (from Gk. -γενής means "forming" or "giving birth to."). The gas had been found in nitric acid?. Chaptal's meaning was that nitrogen gas is the essential part of nitric acid?, in turn formed from saltpetre? (potassium nitrate), then known as nitre?. This word in the more ancient world originally described sodium salts that did not contain nitrate, and is a cognate of natron?.

Nitrogen compounds were well known during the Middle Ages. Alchemists? knew nitric acid? as aqua fortis (strong water). The mixture of nitric and hydrochloric acids was known as aqua regia? (royal water), celebrated for its ability to dissolve gold (the king of metals). The earliest military, industrial, and agricultural applications of nitrogen compounds used saltpetre? (sodium nitrate or potassium nitrate), most notably in gunpowder, and later as fertilizer. In 1910, Lord Rayleigh? discovered that an electrical discharge in nitrogen gas produced "active nitrogen", an allotrope considered to be monatomic. The "whirling cloud of brilliant yellow light" produced by his apparatus reacted with quicksilver? to produce explosive mercury nitride?. Wikipedia, Nitrogen (external link)

Page last modified on Sunday 01 of January, 2012 05:56:19 MST

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