Nitrogen, a nonmetal, is the lightest element of Group VA. Other members of the group are phosphorus (P), arsenic (As), antimony (Sb), and bismuth (Bi).
Credit for discovering nitrogen in 1722 is given to Daniel Rutherford, but Scheele, Cavendish, Priestley, and others about the same time studied "burnt or phlogisticated air," as air without oxygen was then called. Lavoisier was the first to recognize nitrogen as an element, and, since an atmosphere of nitrogen could not support life, he named it azote, meaning 'without life'.
The name was given to the element since it was one of the constituents of nitre, potassium nitrate. The symbol N is an abbreviation of the name.
Nitrogen makes up 78% of the air, by volume.
The estimated amount of nitrogen in the atmosphere is more than 4000 billion tons. Most nitrogen for industrial use is produced by fractional distillation of liquid air.
Nitrogen, as a gas, is colorless, odorless, and a generally inert element. As a liquid it is also colorless and odorless, and is similar in appearance to water.
When nitrogen is heated, it combines directly with magnesium, lithium, or calcium; when mixed with oxygen and subjected to electric sparks, it forms first nitrogen oxide (NO, nitric oxide) and then the brown gas nitrogen dioxide (NO2).
N2(g) + O2(g) 2 NO(g)
2 NO(g) + O2(g) 2 NO2(g)
When N2 is heated under pressure with H2 in contact with a catalyst, ammonia is formed (Haber process). The ammonia thus formed is of the utmost importance as it is used in fertilizers, and it can be oxidized to nitric acid (Ostwald process).
NH3 + O2 + H2O HNO3
The ammonia industry is the largest consumer of nitrogen. (Nitrogen ranks 2nd in industrial production in the U.S., while NH3 ranks 6th.) However, large amounts of the gas are also used by the electronics industry, which uses the gas as a blanketing medium during production of such components as transistors, diodes, etc. The drug industry also uses large quantities. Nitrogen holds promise as a refrigerant both for the immersion freezing of food products and for transportation of foods.
Liquid nitrogen is also used in missile work as a purge for components and insulators for space chambers, and by the oil industry to build up great pressures in wells to force crude oil upward.
Sodium and potassium nitrates are formed by the decomposition of organic matter with compounds of the metals present. In certain dry areas of the world (Chile, for example) these saltpeters are found in quantity.
Nitrogen is present in the protein of foods and is an important consideration in human diet.