Nitrogen, symbol N, gaseous element that makes up the largest portion of the earth's atmosphere. The atomic number of nitrogen is 7. Nitrogen is in group 15 (or Va) ofthe periodic table.Nitrogen was discovered by the British physician DanielRutherford in 1772 and recognized as an elemental gas by the French chemist, Antoine Laurent Lavoiser about1776.Nitrogen is a colorless, odorless tasteless, nontoxic gas. Itcan be condensed into a colorless liquid, which can be compressed into a colorless, crystalline solid. Nitrogen exists in two natural forms, and four radioactive forms (artificial). Nitrogen melts at -210.01degrees C, (-349.02 F), boils at -195.79 C (320.42 F), and has a density of 1.251 g/liter at 0 C (32 F) and 1atmosphere pressure. The atomic weight of nitrogen is 14.007.Nitrogen is obtained from the atmosphere by passing air overheated copper of iron. The oxygen is removed from the air, leaving nitrogen mixed with inert gases. Purenitrogen is obtained by fractional distillation of liquid air; because liquid nitrogen has a lower boilingpoint than liquid oxygen, the nitrogen distills of first an can be collected.Nitrogen compresses about 4/5ths by volume of the atmosphere. Nitrogen is inert and serves as a diluent for oxygen in burning and respiration processes. It is animportant element in plant nutrition; certain bacteria in the soil convert atmospheric nitrogen into a form,such as nitrate, that can be absorbed by plants, a process called nitrogen fixation. Nitrogen in the form ofprotein is an important constituent of animal tissue. The element occurs in the combined state in minerals, ofwhich saltpeter (KNO ) and Chile saltpeter (NaNO ) are commercially important products.Nitrogen combines with other elements only at very hightemperatures of pressures. It is converted to an active form by passing through an electronic dischargeat low pressure. The nitrogen so produced is very active, combining with alkali metals...
