Nitrogen
Symbol: N
Atomic Number: 7
Atomic Mass: 14.00674 amu (atomic mass units)
Melting Point: minus 209.9 C (63.250008 K, minus 345.81998 F)
Boiling Point: minus 195.8 C (77.35 K, minus 320.44 F)
Number of Protons: 7
Number of Neutrons: 7
Number of Electrons: 7
Classification: Non-metal
Crystal Structure: Hexagonal
Density @ 293 K: 0.0012506 grams per cubic centimeter
Color: colorless
The element nitrogen was discovered in 1772 by Daniel Rutherford who was a Scottish physician. The name nitrogen comes from the two Greek words “nitron” and “genes”, “nitron” is the Greek name for the chemical saltpetre and “genes” means forming.
Nitrogen is the most abundant gas in earth’s atmosphere making up 78% of the total. It is estimated that the earth’s atmosphere contains 4,000 trillion tons of nitrogen. The atmosphere is the commercial source of nitrogen as it is extracted from liquid air by the fractional distillation process.
Atmospheric nitrogen consists of two stable isotopes the most common of these isotopes at 99.634% is nitrogen-14 the remaining 0.366% is made up of the isotope nitrogen-15. A number of unstable isotopes of nitrogen have been produced with mass numbers ranging from 10 to 24.
The main commercial use for nitrogen is in the production of ammonia. The Haber process combines nitrogen with hydrogen by heating them under pressure with a suitable catalyst to form ammonia (NH3). Ammonia is then used to manufacture a number of chemicals such as saltpetre or potassium nitrate which is used to make fertilizers, match heads and the explosives used in pyrotechnic displays. The Ostwald process is used to manufacture nitric acid from ammonia.
Nitrogen gas is fairly inert and is used as an atmospheric shield in some welding and soldering operations. It is also used as a shield in the manufacturing of semi-conductors. Nitrogen is used to “top-up” tanks used for the storage and shipping of explosive liquids.
Nitrogen is pumped into oil-wells by the petroleum industry to pressurize the wells and force the oil out.
Liquid nitrogen is used in low temperature refrigeration. As such it is used in the cryopreservation of biological tissues. It is also used in scientific experimentation where a low temperature is required.
Nitrogen is important biologically it is found in the amino acids that form proteins and in nucleic acids. The bacteria present on the roots of some plants such as clover can “fix” nitrogen in the soil making it available to the plants.
