什麼是氮

氣態化學元素，化學符號N，原子序數7。無色、無臭、無味的氣體，佔地球大氣的78%，也是所有生物體的組成部分。它是最穩定的雙原子分子N2，可用來產生惰性的氣體氛圍，或用於稀釋氣體。商業上通過液化空氣的蒸餾來生產氮氣。自然界通過土壤裡的微生物可達成固定氮作用，而在工業上則利用哈伯－博施法將它轉化成可溶於水的化合物（包括氨和硝酸鹽）。氨是其他氮化合物（尤其是硝酸鹽和亞硝酸鹽）的起始物質，這些化合物主要用於農業肥料和炸藥。氮能生成幾種氧化物：一氧化二氮；氧化氮（NO），最近發現它在生理過程中起關鍵作用；二氧化氮，以及其他形式（包括N2O3和N2O5），它們會造成空氣汙染（尤其在日光照射下），故而臭名昭彰。其他的化合物包括氮化物，是由氮和金屬生成的異常堅硬的材料；氰化物；疊氮化物，用作引爆劑和雷管；還有數千種含氮的有機化合物，以功能團或者線性或環狀結構（參閱heterocyclic compound）的形式存在。

nitrogen

Gaseous chemical element, chemical symbol N, atomic number 7. A colorless, odorless, tasteless gas, it makes up 78% of the earth's atmosphere and is a constituent of all living matter. As the almost inert diatomic molecule N2, it is useful as an inert atmosphere or to dilute other gases. Nitrogen is commercially produced by distillation of liquefied air. Nitrogen fixation, achieved naturally by soil microbes and industrially by the Haber-Bosch process, converts it to water-soluble compounds (including ammonia and nitrates). Ammonia is the starting material for most other nitrogen compounds (especially nitrates and nitrites), whose main uses are in agricultural fertilizers and explosives. Nitrogen forms several oxides: nitrous oxide; nitric oxide (NO), recently found to play key roles in physiology; and nitrogen dioxide (NO2) and other forms (including N2O3 and N2O5) notorious for causing air pollution, especially when acted on by sunlight. Other compounds include the nitrides, exceptionally hard materials made from nitrogen and a metal; cyanides; azides, used in detonators and percussion caps; and thousands of organic compounds containing nitrogen in functional groups or in a linear or ring structure (see heterocyclic compound). See also nitrogen cycle.