Editing Nitrogen (section)

===Organic nitrogen compounds===
Nitrogen is one of the most important elements in [[organic chemistry]]. Many organic [[functional group]]s involve a [[carbon–nitrogen bond]], such as [[amide]]s (RCONR<sub>2</sub>), [[amine]]s (R<sub>3</sub>N), [[imine]]s (RC(=NR)R), [[imide]]s (RCO)<sub>2</sub>NR, [[azide]]s (RN<sub>3</sub>), [[azo compound]]s (RN<sub>2</sub>R), [[Cyanate ester|cyanate]]s (ROCN), [[isocyanate]]s (RNCO), [[nitrate]]s (RONO<sub>2</sub>), [[nitrile]]s (RCN), [[isonitrile]]s (RNC), [[Nitrite#Organic nitrites|nitrite]]s (RONO), [[nitro compound]]s (RNO<sub>2</sub>), [[nitroso compound]]s (RNO), [[oxime]]s (RC(=NOH)R), and [[pyridine]] derivatives. C–N bonds are strongly polarised towards nitrogen. In these compounds, nitrogen is usually trivalent (though it can be tetravalent in [[quaternary ammonium salt]]s, R<sub>4</sub>N<sup>+</sup>), with a lone pair that can confer basicity on the compound by being coordinated to a proton. This may be offset by other factors: for example, amides are not basic because the lone pair is delocalised into a double bond (though they may act as bases at very low pH, being protonated at the oxygen), and [[pyrrole]] is not basic because the lone pair is delocalised as part of an [[aromaticity|aromatic]] ring.<ref name="Jerry">{{JerryMarch}}</ref> The amount of nitrogen in a [[chemical substance]] can be determined by the [[Kjeldahl method]].<ref>{{cite book|year=2008|doi=10.1007/978-1-4020-6754-9_9066|isbn=978-1-4020-6753-2|title=Encyclopedia of Genetics, Genomics, Proteomics and Informatics|page=1063|chapter=Kjeldahl Method|last1=Rédei|first1=George P}}</ref> In particular, nitrogen is an essential component of [[nucleic acids]], [[amino acid]]s and thus [[protein]]s, and the energy-carrying molecule [[adenosine triphosphate]] and is thus vital to all life on Earth.<ref name="Jerry" />