Element Nitrogen, N, Non Metal

There is present in the air, besides oxygen, another substance which constitutes the greater part both by weight and by volume. From the fact that the residue of the air after removal of the oxygen can support neither combustion nor life, it was called azote, but it is now called nitrogen. Its chemical symbol is N, from nitrogenium. This name is due to the fact that nitrogen is an essential component of saltpetre (nitrum). Its combining weight is N = 14.04.

The properties of nitrogen are essentially those of the air minus those due to oxygen. Thus, it is colourless, odourless, and only slightly soluble in water. Its molar weight is 28; as gas, therefore, it has the formula N₂. It is distinguished from oxygen essentially by the fact that it is capable only in a very slight degree of reacting chemically with other substances. There are only very few substances which can unite directly with nitrogen. If, however, the nitrogen has passed into combination, the substances which are formed show a very considerable variety and power of transformation, so that the range of nitrogen compounds is a large and important one.

Compounds of nitrogen are of frequent occurrence both in the mineral and, more especially, in the organic kingdoms. Of the former there may be mentioned the important groups of nitric acid and ammonia; these will presently be discussed in detail. In the organic kingdom, nitrogen is in so far of especial importance as the substances with which the phenomena of life are directly connected, and whose presence appears to be necessary for the processes of life, viz., the albuminoids, all contain nitrogen.

In 1777 Henry Cavendish carried out the following experiment: he passed air over glowing charcoals, and then treated it by alkali. Residual gas was called mephitic air. Contemporary chemistry makes it clear that air oxygen in reaction with glowing coals was bound in carbon dioxide which then reacted with alkali. The residue was consisted mostly of nitrogen. So, Cavendish extracted nitrogen but failed to understand that it was an elementary substance, i.e. a new chemical element. In the same year Cavendish informed Joseph Priestley about the results of this experiment.

Nitrogen was also studied at about the same time by Carl Wilhelm Scheele.

Nitrogen was described by Daniel Rutherford in 1772, who called it "noxious air". He published his master's thesis, in which he showed the main chemical properties of nitrogen. For this reason he is formally considered as nitrogen discoverer.

Nitrogen denominatives are constituted from Latin nitrogenium, where nitrum (from Greek nitron) means "native soda", and genes means "forming". As it was said in Ruland's 1612 Lexicon alchemiae (Dictionary of Alchemy): "Nitrum, baurach, Sal petrosum, nitrum, Germans call it Salpeter, Bergsalz, the same as Sal petrae".

In space compounds that contain nitrogen have been observed in gaseous nebula, in solar atmosphere; nitrogen has been detected in interstellar space. Molecular nitrogen is a major constituent of atmospheres of Uranus, Neptune, and occurs in trace amounts of other planetary atmospheres and is estimated to be the 4^th most abundant chemical element in Solar system after hydrogen, helium and oxygen. Nitrogen two-atom molecules are the largest single component of the Earth's atmosphere (78.082% by volume of dry air, 75.3% by weight in dry air, which is 3.87x10¹⁵ ton).

Containing of nitrogen in the Earth's crust, according to different authors, is estimated to be (0.7-1.5)x10¹⁵ ton, in which 6x10¹⁰ in humus and 1.3x10¹⁶ ton in Earth's mantle. Such mass ratio hints a conclusion that the upper layer of the mantle serves as the main source of nitrogen which is then supplied into the atmosphere through volcanic eruptions.

The mass of nitrogen in hydrosphere is estimated as 2x10¹³ ton taking into account the simultaneous processes of it's dissolution in water and transfer into atmosphere. The mass of nitrogen compounds in hydrosphere is approximately 7x10¹¹ ton.

Nitrogen is crucially important for plants and animals life supporting. It is an essential part of all living tissues as proteins (16-18% by mass), nucleic acids, nucleoproteins, chlorophyll, haemoglobin and other molecules. Therefore significant quantity of nitrogen, around 1.9x10¹¹ tons is found in living creatures, dead organic matter and dispersed material of seas and oceans. As a result of decaying and decomposition process, in benign environment, deposits of useful nitrogen-containing fossil resources may be formed, such as Chilean saltpeter (sodium nitrate with contaminant of other nitrates), Norwegian saltpeter, Indian saltpeter and so on.