Nitrogen

   Dinitrogen is obtained industrially by fractional distillation of liquid air, and the product contains some Ar and traces of O₂.  Dioxygen can be removed by addition of a small amount of H₂ and passage over a Pt catalyst, or by bubbling the gas through an aqueous solution of CrCl₂. Small amounts of N₂ can be prepared by thermal decomposition of sodium azide. The latter should be carried out cautiously because of the risk of explosion; ammonium nitrite (NH₄NO₂) is potentially explosive, as is ammonium nitrate which is a powerful oxidant and a component of dynamite. In car airbags, the decomposition of NaN₃ is initiated by an electrical impulse.

  Dinitrogen is generally unreactive. It combines slowly with Li at ambient temperatures and when heated, with the group 2 metals, Al, Si, Ge  and many d-block metals. The reaction between CaC₂ and N₂ is used industrially for manufacturing the nitrogenous fertilizer calcium cyanamide.

   Many elements (e.g. Na, Hg, S) which are inert towards N₂ do react with atomic nitrogen, produced by passing N₂ through an electric discharge. At ambient temperatures, N₂ is reduced to hydrazine (N₂H₄) by vanadium(II) and magnesium hydroxides. A large number of d-block metal complexes containing coordinated N₂ are known N₂ is isoelectronic with CO and the bonding in complexes containing the N₂ ligand can be described in a similar manner to that in metal carbonyl complexes.