Editing Period 2 element (section)

===Nitrogen===
{{main article|Nitrogen}}
[[File:Liquidnitrogen.jpg|thumb|left|150px|Liquid nitrogen being poured]]

Nitrogen is the chemical element with atomic number 7, the symbol '''N''' and [[atomic mass]] 14.00674&nbsp;u. Elemental nitrogen is a colorless, odorless, tasteless and mostly [[Inert gas|inert]] [[diatomic]] gas at [[standard conditions]], constituting 78.08% by volume of [[Earth's atmosphere]]. The element nitrogen was discovered as a separable component of air, by Scottish physician [[Daniel Rutherford]], in 1772.<ref>{{Cite book |url=https://archive.org/details/elementsofchemis0000lavo |url-access=registration |page=[https://archive.org/details/elementsofchemis0000lavo/page/15 15] |title=Elements of chemistry, in a new systematic order: containing all the modern discoveries |author=Lavoisier, Antoine Laurent |author-link=Antoine Lavoisier |publisher=Courier Dover Publications |year=1965 |isbn=0-486-64624-6}}</ref> It occurs naturally in form of two isotopes: nitrogen-14 and nitrogen-15.<ref name=wen>[http://www.webelements.com/nitrogen/ Nitrogen] at WebElements.</ref>

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 breaking the bond to convert the {{chem|N|2}} molecule 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.

Nitrogen occurs in all living organisms, and the [[nitrogen cycle]] describes movement of the element from air into the [[biosphere]] and organic compounds, then back into the atmosphere. Synthetically produced [[nitrate]]s are key ingredients of industrial [[fertilizer]]s, and also key pollutants in causing the [[eutrophication]] of water systems. Nitrogen is a constituent element of [[amino acid]]s and thus of [[protein]]s, and of [[nucleic acid]]s ([[DNA]] and [[RNA]]). It resides in the [[chemical structure]] of almost all [[neurotransmitter]]s, and is a defining component of [[alkaloid]]s, biological molecules produced by many organisms.<ref name="Lightning">{{Cite book |title = Lightning: Physics and Effects |first = Vladimir A. |last = Rakov |author2=Uman, Martin A.  |publisher = Cambridge University Press |year = 2007 |isbn = 978-0-521-03541-5 |page = 508 |url=https://books.google.com/books?id=TuMa5lAa3RAC&pg=PA508}}</ref>