Nítrójìn: Ìyàtọ̀ láàrin àwọn àtúnyẹ̀wò
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{{Infobox nitrogen}}
'''Nítrójìn''' tàbí '''Náítrójìn''' is a [[chemical element]] with symbol '''N''' and [[atomic number]] 7. Elemental nitrogen is a colorless, odorless, tasteless, and mostly [[inert]] [[diatomic]] gas at [[standard conditions]], constituting 78.09% by volume of [[Earth's atmosphere]].<ref name="Gray" >{{cite book|last=Gray|first=Theodore|title=The Elements: A Visual Exploration of Every Known Atom in the Universe|year=2009|publisher=Black Dog & Leventhal Publishers|location=New York|isbn=978-1-57912-814-2}}</ref> The element nitrogen was discovered as a separable component of air, by Scottish physician [[Daniel Rutherford]], in 1772. It belongs to the [[pnictogen]] family.
Nitrogen is a common element in the universe, estimated at about seventh in total abundance in our [[Milky Way|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 ([[propellant]]s and [[explosive]]s), and [[cyanide]]s, contain nitrogen. The extremely strong bond in elemental nitrogen dominates nitrogen chemistry, causing difficulty for both organisms and industry in converting (or "fixing") the {{chem|N|2}} into useful [[Chemical compound|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 [[nitrate]]s are key industrial [[fertilizer]]s,<ref name="Gray"/> 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 [[alkaloid]]s (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 [[neurotransmitter]]s (for example, synthetic [[amphetamine]]s).
Nitrogen occurs in all organisms, primarily in [[amino acid]]s (and thus [[proteins]]) and also in the [[nucleic acid]]s ([[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.
==History and etymology==
Nitrogen is formally considered to have been discovered by Scottish physician [[Daniel Rutherford]] in 1772, who called it ''noxious air'' or ''fixed air''.<ref>{{Cite book|url=http://books.google.com/?id=yS_m3PrVbpgC&pg=PR15|page=15|title=Elements of chemistry, in a new systematic order: containing all the modern discoveries|author=Lavoisier, Antoine Laurent|authorlink=Antoine Lavoisier|publisher=Courier Dover Publications|year=1965|isbn=0-486-64624-6}}</ref> 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 ''[[Phlogiston theory|phlogisticated air]]''. Nitrogen gas was [[inert]] enough that [[Antoine Lavoisier]] referred to it as "[[wikt:mephitic air|mephitic air]]" or ''azote'', from the Greek word {{lang|el|ἄζωτος}} (''azotos'') meaning "lifeless".<ref>''Elements of Chemistry'', trans. Robert Kerr (Edinburgh, 1790; New York: Dover, 1965), 52.</ref> 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<ref>[http://www.etymonline.com/index.php?term=nitrogen nitrogen]. Etymonline.com. Retrieved on 2011-10-26.</ref> 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. [[Alchemy|Alchemists]] knew nitric acid as ''aqua fortis'' (strong water). The mixture of nitric and [[hydrochloric acid]]s 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, [[John William Strutt, 3rd Baron Rayleigh|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 [[mercury (element)|quicksilver]] to produce explosive [[mercury nitride]].<ref>[http://www.lateralscience.co.uk/activen/index.html Lord Rayleigh's Active Nitrogen]. Lateralscience.co.uk. Retrieved on 2011-10-26.</ref>
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