The element nitrogen is a colorless, tasteless, odorless gas which is mostly an inert diatomic (N2) gas at standard conditions. It's one of the most widespread elements found on Earth and makes up about 78% of the Earth's atmosphere and 3% of Mars' atmosphere. The name 'Nitrogen' has been derived from the Latin word 'nitrogenium', wherein nitrum originates from the Greek word nitron and means 'native soda' and genes means 'forming'.
History of Nitrogen
In 1772, Daniel Rutherford, a chemist and physician, discovered nitrogen in the northern country of Scotland. He removed carbon dioxide and oxygen from air and showed that the residual substance did not support life. An experiment was conducted by him, which involved placing a mouse in a bell jar and waiting for the animal to suffocate. Once the mouse died, he placed another mouse in the same jar and watched it die in an even shorter period. He thus called nitrogen as 'noxious air'. At the same time, Carl Wilhelm Scheele, Joseph Priestley and Henry Cavendish were also conducting research on nitrogen. They referred to it as 'burnt air' or dephlogisticated air, which means air without oxygen.
Occurrence of Nitrogen
In the atmosphere, nitrogen exists as a diatomic molecule (N2), that is nitrogen atoms bond in pairs and occur as a molecule in air. Besides being the most abundant element (78%) in the Earth's atmosphere, it has also been detected in interstellar space. It is the fourth most abundant chemical element in the Solar System after hydrogen, helium and oxygen and is a major constituent in the atmosphere of planets such as Uranus and Neptune, and also in smaller amounts in the atmosphere of other planets. Nitrogen is created as a result of fusion process that takes place in stars such as the Sun and occurs in a number of minerals such as sodium nitrate, potassium nitrate and sodium chloride.
Nitrogen is Essential for Living Organisms
Nitrogen forms an essential part of all living tissues in the form of proteins, nucleoproteins, hemoglobin, nucleic acids, chlorophyll and other such molecules. It is seen to make up 3% of the weight of human body and 4% of the dry weight of plant matter. Further, it is also a large component of animal waste in the form of uric acid, urea, ammonium compounds and other derivatives of these nitrogenous products. Around 1.9x1011 tons of the element are found in living creatures, in dispersed material of seas and oceans and dead organic matter.
Properties of Nitrogen
Nitrogen in its elemental form was regarded to be inert, which is why Antoine Lavoisier assumed the element to be a dead gas and called nitrogen 'azote' meaning 'lifeless'. Nitrogen is a non-metal and is placed on the right side of the periodic table. It is a poor conductor of heat and electricity. It has an electronegativity of 3.04 and possesses five electrons in the outer shell, thereby forming trivalent bonds in most compounds. Converting N2 into other compounds is quite difficult because of the strong triple bond between the two N atoms. Twelve isotopes (mass numbers 11 - 19) of nitrogen are known, of which 14N and 15N are stable. At 77K nitrogen condenses into a liquid and resembles water, and at 63K it freezes.
Applications of Nitrogen
This element finds its applications in both natural as well as artificial areas. Farmers are seen to rely a lot on nitrogen as it is essential for the growth of crops and in nitrogen cycle. This is why farmers are seen to grow plants of the legume family as cover crops, since they are capable of restoring nitrogen to the soil. The common uses of nitrogen are in coolants (for immersion freezing), explosives (key element in dynamite), gunpowder, nitrogen generators, liquid nitrogen and nitrogen dioxide preparation, rocket fuels and so on.
However, the greatest application of nitrogen is in the manufacture of ammonia (Haber's process) to produce nitric acid (Ostwald process) as well as in the manufacture of fertilizers. Further, it is also used in welding and oil industry to force crude oil upwards by building pressure in the oil wells. Application of nitrogen gas is seen when an inert atmosphere, that is an atmosphere without oxygen is needed, such as in light bulbs. Further, liquid nitrogen is used as a refrigerant and is used to freeze food materials. Often food items, chemicals, documents, reproductive cells (eggs and sperms) in fertility clinics are stored in nitrogen as it prevents them from reacting with air or water or even getting oxidized.
Nitrogen is essential for life on Earth, however, it has its hazards. If nitrogen gas is released rapidly in an enclosed space, it is seen to displace oxygen from air causing an asphyxiation hazard. Liquid nitrogen when brought in direct contact with skin is seen to cause frost bite eventually. Therefore, while handling nitrogen gas or liquid, one must be careful and must undertake all precautionary measures.