Nítrójìn
Nítrójìn tàbí Náítrójìn ni ẹ́límẹ̀ntì kẹ́míkà kan tó ní àmì-ìdámọ̀ N àti nọ́mbà átọ̀mù 7. Nítrójìn bíi ẹ́límẹ̀ntì jẹ́ ẹ̀fúùfù átọ̀mùméjì aláilawọ̀, aláìlóòórùn, aláìní-ìtọ́wò àti aláìkópa ní ìgbà onídéédéé, tó jẹ́ 78.09% gẹ́gẹ́bí ìkúnnú ojúọ̀run Ayé. Nítrójìn jẹ́ wíwárí gẹ́gẹ́bí ohun inú afẹ́fẹ́ yíyàtọ̀, látọwọ́ oníṣègùn ará Skọ́tlàndì Daniel Rutherford, ní 1772. Nítrójìn wà nínú ẹbí àwọn pníktójìn.
Nítrójìn jẹ́ ẹ́límẹ̀ntì tó wọ́pọ̀ nínú àgbálá-ayé, estimated at about seventh in total abundance in our galaxy and the Solar System. It is synthesised by fusion of carbon and hydrogen in supernovas. Due to the volatility of elemental nitrogen and its common compounds with hydrogen and oxygen, nitrogen is far less common on the rocky planets of the inner Solar System, and it is a relatively rare element on Earth as a whole. However, as on Earth, nitrogen and its compounds occur commonly as gases in the atmospheres of planets and moons that have atmospheres.
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 converting (or "fixing") the 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 causing the eutrophication of water systems.
Outside their major uses as fertilizers and energy-stores, nitrogen compounds are versitile organics. Nitrogen is part of materials as diverse as Kevlar fabric and cyanoacrylate "super" glue. Nitrogen is a constituent of molecules in every major pharmacological drug class, including the 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 being metabolized to natural nitric oxide. Plant alkaloids (often defense chemicals) contain nitrogen by definition, and thus many notable nitrogen-containing drugs, such as caffeine and morphine are either alkaloids or synthetic mimics that act (as many plant alkaloids do) upon receptors of animal neurotransmitters (for example, synthetic amphetamines).
Nitrogen occurs in all organisms, primarily in amino acids (and thus proteins) and also in the nucleic acids (DNA and RNA). The human body contains about 3% by weight 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.
Nitrogen is formally considered to have been discovered by Scottish physician Daniel Rutherford in 1772, who called it "noxious air" or "fixed air". The fact that there was constituent 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 ("azotos") meaning "lifeless". In it, animals died and flames were extinguished. Lavoisier's name for nitrogen is used in many languages (French, Italian, Polish, Russian, Albanian, 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 by 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.