Nitrogen makes up 78.1% of Earth’s atmosphere. Daniel Rutherford discovered this colorless, odorless and tasteless gas in 1772. After removing both oxygen and carbon dioxide from air, Rutherford found the remaining gas supported neither life nor fire. Its name comes from the Greek words for saltpetre and forming – “nitron” and “genes”.
Other scientists working on the gas at about the same time as Rutherford named the gas “burnt air” or “dephlogisticated air”, which means without oxygen. Because it was unable to support life, Antoine Laurent Lavoisier called it “azote”, which means without life. However, without nitrogen we would have no life, as it is an essential element forming many biological compounds including amino acids, the building blocks of proteins. The nitrogen cycle, through which bacteria fix atmospheric nitrogen, allowing its usage by plants then animals, before bacteria release the gas to the atmosphere again, is one of the most important biological cycles.
Nitrogen (symbol N), with the atomic number 7, occurs in period 2, group 15 (the Pnictogen group) of the periodic table. It has the atomic weight of 14.0067 and a density of 0.0012506 grams per cubic centimeter. The ionization energy of the element is 14.534 eV.
The commercial source of the element is the air we breathe. To obtain nitrogen from the atmosphere liquefied air is subjected to fractional distillation. There is no danger of this resource running dry in the future, as the Earth’s atmosphere contains an estimated 4,000 trillion tons of the element. In fact, it is the fifth most abundant element in the universe. However, the Martian atmosphere contains less than 3% of the gas. Natural nitrogen consists of two stable isotopes mainly nitrogen-14 (99.634%) with a small amount of nitrogen-15 (0.366%).
Commercially the most important usage of nitrogen is the production of ammonia (NH3) by the Haber process. This combines nitrogen with hydrogen to form the pungent gas. Ammonia forms the basis of many other commercially important chemicals such as fertilizers and some explosives.
As nitrogen gas itself is relatively inert, it provides a protective atmosphere for sensitive industrial processes such as the production of semiconductors.
With a boiling point of minus 195.79°C (77.36 K, minus 320.44°F) and a melting point of minus 210.00°C (63.15 K, minus 346.00°F), liquid nitrogen is an efficient liquid refrigerant. As such, it is used extensively in the preservation of many biological samples.
Oil companies pump nitrogen gas into oil wells to increase the pressure within the well and aid in the oil’s extraction. Nitrogen is safe for this purpose, as it does not support combustion.
Reference sources
Los Alamos National Laboratory Chemistry Division
Jefferson Laboratories Science Education website
