Nitrogen



Nitrogen ( / ˈ n aɪ t r ɵ dʒ <span class="IPA" style="font-family: 'Arial Unicode MS', 'Lucida Sans Unicode'; "><span style="border-bottom-width: 1px; border-bottom-style: dotted; border-bottom-color: initial; " title="schwa 'a' in 'about'">ə <span class="IPA" style="font-family: 'Arial Unicode MS', 'Lucida Sans Unicode'; "><span style="border-bottom-width: 1px; border-bottom-style: dotted; border-bottom-color: initial; " title="'n' in 'nigh'">n <span class="IPA" style="font-family: 'Arial Unicode MS', 'Lucida Sans Unicode'; " title="Representation in the International Phonetic Alphabet (IPA)">/ <span class="IPA" style="font-family: 'Arial Unicode MS', 'Lucida Sans Unicode'; " title="English pronunciation respelling"> ny -trə-jən ) 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.<sup class="reference" id="cite_ref-Gray_0-0" style="line-height: 1em; ">[1] The element nitrogen was discovered as a separable component of air, by Scottish physician Daniel Rutherford, in 1772.

<p style="margin-top: 0.4em; margin-bottom: 0.5em; line-height: 19px; font-family: sans-serif; ">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 N<sub style="line-height: 1em; ">2 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.

<p style="margin-top: 0.4em; margin-bottom: 0.5em; line-height: 19px; font-family: sans-serif; ">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,<sup class="reference" id="cite_ref-Gray_0-1" style="line-height: 1em; ">[1] and key pollutants in causing the eutrophication of water systems. Nitrogen is a constituent element of amino acids and thus of proteins andnucleic 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.