All practice pages/Interatomic theory/Elements
Element 7, a nonmetal
Four fifths of every breath you take, and nearly inert in that form; in compounds, the element that every protein and every gene is built on.
Period 2, group 15: the first of the three that draw the top of the 7. The other nonmetals are tinted, and every cell opens its own article.
Five valence electrons, three short of eight. Two nitrogen atoms share three pairs, a triple bond, and each ends up with a full octet.
Nitrogen gas is 78% of the air by volume. In the ground it is scarce, because most nitrates dissolve and wash away; the one great natural deposit was the caliche of the Atacama desert in Chile. Every protein and every strand of DNA contains it, which is why nitrogen fertilizer matters so much.
Daniel Rutherford separated it from air in 1772 and called it noxious air, because a mouse could not live in it. Lavoisier called it azote, without life. The name nitrogen, nitre-former, came from Jean-Antoine Chaptal in 1790.
As N₂ gas it keeps food and chemicals from reacting with air, and as a liquid it freezes and preserves. Its compounds do even more: ammonia and nitrates feed the world's crops, nitrates and nitro compounds make explosives, and nitrogen is part of every protein, of nylon and of many medicines.