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单词 nitrogen
释义
nitrogen

Chemistry
  • A colourless gaseous element belonging to group 15 (formerly VB) of the periodic table; a.n. 7; r.a.m. 14.0067; d. 1.2506 g dm−3; m.p. –209.86°C; b.p. –195.8°C. It occurs in air (about 78% by volume) and is an essential constituent of proteins and nucleic acids in living organisms (see nitrogen cycle). Nitrogen is obtained for industrial purposes by fractional distillation of liquid air. Pure nitrogen can be obtained in the laboratory by heating a metal azide. There are two natural isotopes: nitrogen–14 and nitrogen–15 (about 3%). The element is used in the Haber process for making ammonia and is also used to provide an inert atmosphere in welding and metallurgy. The gas is diatomic and relatively inert – it reacts with hydrogen at high temperatures and with oxygen in electric discharges. It also forms nitrides with certain metals. Nitrogen was discovered in 1772 by Daniel Rutherford (1749–1819).

    https://www.webelements.com/nitrogen/ Information from the WebElements site


Biology
  • Symbol N. A colourless gaseous element that occurs in air (as dinitrogen, N2, about 78% by volume) and is an essential constituent of proteins and nucleic acids in living organisms (see nitrogen cycle).


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