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Chemistry Connections of nitrogen - saltpeter, nitric acid, ammonia - were known long before invention of nitrogen in a free condition. In 1772 D. Rutherford, burning phosphorus and other substances in a glass bell, has shown that the gas remaining after combustion does not support breath and burning. He named it suffocating air. In 1787 A. Lavoisier has established, that the "vital" and "suffocating" gases included in air, are simple substances, and has offered the name "nitrogen." In 1784 G.
Cavendish has shown, that nitrogen is a part of saltpeter. Because of this a Latin name of nitrogen offered in 1790 by Z. A. Chapter origins. To the beginning of XIX century chemical inertness of nitrogen in a free condition and its exclusive role in connections with other elements as the connected nitrogen have been found out. Nitrogen is one of the most widespread elements on the Earth, and its basic part is concentrated in a free condition in an atmosphere.
In air free nitrogen makes 78, 09 % on volume, not including its insignificant impurity as ammonia and oxides. Natural connections of nitrogen are chloride ammonium NH 4 CI and various nitrates. Large congestion's of saltpeter are characteristic for a dry deserted climate (Chile, Central Asia). For long time saltpeter was the main supplier of nitrogen for the industry.
Small amounts of the connected nitrogen are in coal (1 - 2, 5 %) and oil (0, 02 - 1, 5 %), and also in waters of the rivers, the seas and oceans. Nitrogen collects in soil (0, 1 %) and in alive organisms (0, 3 %). Though the name "nitrogen" means not supporting lives, actually it is the most necessary element for ability to live. In fiber of animals and the person contains 16 - 17 % of nitrogen.
In organisms of carnivores fiber is formed due to the consumed albumen's available in organisms of herbivores and in plants. Plants synthesize fiber, acquiring nitrogenous substances contained in ground, mainly inorganic. Significant amounts of nitrogen act in ground thanking to the nitrogenous microorganisms, which are able to transform free nitrogen of air in connections of nitrogen. Nitrogen is the fourth element on prevalence in solar system (after hydrogen, helium and oxygen). The external electronic environment of atom of nitrogen consists of 5 electrons. More often nitrogen in connections 3 -covalent due to not coupled electrons (as in ammonia NH 3).
Presence of not divided pair of electrons can result in formation of one more covalent connections, and nitrogen becomes 4 -covalent (as an ion of ammonium NH 4 +). Degrees of oxidation of nitrogen vary from + 5 (in N 2 O 5) up to- 3 (in NH 3). In usual conditions in a free condition nitrogen forms molecule N 2, where atoms of nitrogen are connected by three covalent connections. The molecule of nitrogen is very steady. Its energy for dissociation on atoms makes 942900 joule / mole , therefore even at temperature 33000 the degree of dissociation of nitrogen makes only about 0, 1 %. In the nature there are two stable isotopes of nitrogen: with mass number 14 and with mass number 15.
Their ratio makes 99, 635: 0, 365. Therefore the nuclear weight of nitrogen is equal 14, 008. Unstable isotopes of nitrogen 12 N, 13 N, 16 N, 17 N are received synthetic. Schematically electronic structure of atom of nitrogen is those that on an external (second) electronic environment are 5 electrons which can participate in formation of chemical connections. Orbital of nitrogen can also accept electrons. That means that the formation of connections with a degree of oxidation from (-III) up to (V) is possible, and they are known.
The basic part of extracted free nitrogen is used for industrial production of ammonia which then in significant amounts is processed on nitric acid, fertilizers, explosives, etc. Besides direct synthesis of ammonia from elements, industrial value for linkage of nitrogen of air has developed in 1905 cyanamide method that is based on the fact that at 10000 carbide calcium reacts with free nitrogen. Formed cyanamide calcium at action of superheated water pair decays with allocation of ammonia Free nitrogen applies in many industries: as the inert environment at various chemical and metallurgical processes, for filling free space in mercury thermometers, at swapping combustible liquids, etc. Liquid nitrogen finds application in various refrigerating machineries. It is stored and transported in steel vessels, gaseous nitrogen in the compressed condition - in cylinders. Widely apply many connections of nitrogen.
Manufacture of the connected nitrogen began to develop strenuously after World War I and has now achieved huge scales. Bibliography: Calvin, M. , 1969, Chemical Evolution: Oxford, Oxford University Press, 278 p. Dickerson, R. E. , 1978, Chemical evolution and the origin of life: Scientific American, v. 239, no. 3, p. 70 - 108. Schramm, D. N. , 1974, The Age of the Elements: Scientific American, v. 230, no. 1, p. 69 - 77.
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