History ------- (L. nitrum, Gr. nitron, native soda; genes, forming) Discovered by Daniel Rutherford in 1772. At about the same time, Scheele, Cavendish, Priestley, and others studied "burnt or dephlogisticated air," as air without oxygen was then called. Sources ------- Nitrogen makes up 78% of the air, by volume. The atmosphere of Mars, by comparison, is 2.6% nitrogen. From an inexhaustible source in our atmosphere, it can be obtained by liquefaction and fractional distillation. Nitrogen molecules give the orange-red, blue-green, blue-violet, and deep violet shades to the aurora. Compounds --------- The element is so inert that Lavoisier named it azote, meaning without life. Yes, its active compounds are found in foods, poisons, fertilizers, and explosives. Nitrogen can also be easily prepared by heating a water solution of ammonium nitrite. 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. Two allotropic forms of solid nitrogen exist, with the transition from the alpha to the beta form taking place at -237C. 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 these saltpeters are found in quantity. Ammonia, nitric acid, the nitrates, the five oxides, TNT, the cyanides, etc. are but a few of the important compounds. Uses ---- When nitrogen is heated, it combines directly with magnesium, lithium, or calcium; when mixed with oxygen and subjected to electric sparks, it forms first nitric acid (NO) and then the dioxide (NO2); when heated under pressure with a catalyst with hydrogen, ammonia is formed (Haber process). The ammonia is used in fertilizers and can be oxidized to nitric acid (Ostwald process). The ammonia industry is the largest consumer of nitrogen. Large amounts of gas are also used by the electronics industry as a blanketing medium when producing transistors, diodes, etc. Large quantities of nitrogen are used in annealing stainless steel and other steel mill products. The drug industry also uses large quantities. Nitrogen is used 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, insulators for space chambers. The oil industry uses nitrogen to increase the pressure in wells to force crude oil upward.