# The periodic table/Nitrogen
## Discovery

Nitrogen was discovered in 1772 by Daniel Rutherford in Edinburgh, Scotland. The name is derived from the Greek, 'nitron' and 'genes' meaning nitre forming.
Nitrogen gas itself was obtained in the 1760s by both Henry Cavendish and Joseph Priestley. They did this by removing the oxygen from air, but neither man deduced that it was an element. The first person to suggest this was the young student Daniel Rutherford in his doctorate thesis of September 1772.

## Quick Facts

| Name: Nitrogen Symbol: N Mass: 14.00674 Atomic Number: 7 Electron Configuration: [He] 2s$^2$ 2p$^3$ | Classification: non-metal CAS Number: 7727-37-9 Appearance: colourless odourless gas Discovery in: 1772 Key Isotopes: $^{14}$N Allotropes: N$_2$ | Density: 1.2506 g/L Crystal Structure: hexagonal Melting Point: -210 °C Boiling Point: -195.795 °C |

## Uses

About 50 million tonnes of nitrogen are extracted every year by the Haber Process, mainly for the manufacture of fertilisers but also for making plastics, dyes and explosives. Large amounts of nitrogen are also used by the electronics industry, which uses the gas as a blanketing medium during production of components such as transistors, diodes etc. Large quantities of nitrogen are used in annealing stainless steel and other steel mill products. Liquid nitrogen is used as a refrigerant for storing sperm, eggs and other cells for medical research and reproductive technology, as well as for the preservation of food products and for their transportation. Liquid nitrogen is also used in missile work and by the oil industry to build up great pressures in wells to force crude oil upwards.
Nitrogen is cycled naturally by living organisms (The nitrogen cycle). It is taken up in solution by green plants and algae as nitrate to build up the bases needed for constructing DNA and RNA and for all amino acids which are used for constructing proteins. Non-photosynthesising life forms, such as animals, obtain their nitrogen by consuming other living things and digesting the proteins and DNA into their constituent bases and amino acids to be reformed for their own use, otherwise excreting it mostly as urea. Microbes in the soil convert the nitrogen compounds back to nitrates for the plants to re-use, hence the value of returning animal excrement to the fields. The nitrate supply is replenished by nitrifying bacteria which are able to ‘fix’ molecular nitrogen directly from the atmosphere. Crop yields can be greatly enhanced by adding additional ‘fixed’ nitrogen to the soil in the form of chemical fertilisers manufactured from Haber Process ammonia.
Nitrogen makes up 78% of the air, by volume. From this source it can be obtained by liquefaction and fractional distillation. In compound form it is found in all living things and hence also in coal and to a lesser extent in other fossil fuels.

## Atomic Data

| Atomic radius: 1.550 Å Covalent radius: 0.71 Å Electronegativity: 3.040 Electron affinity: unstable | Ionisation energies First: 1402.330 kJ mol$^{-1}$ Second: 2856.089 kJ mol$^{-1}$ Third: 4578.152 kJ mol$^{-1}$ Fourth: 7475.051 kJ mol$^{-1}$ Fifth: 9444.961 kJ mol$^{-1}$ Sixth: 53266.790 kJ mol$^{-1}$ Seventh: 64360.105 kJ mol$^{-1}$ |

## Supply Risk

Unknown

## Oxidation States and Isotopes

Common oxidation states: 5, 4, 3, 2, -3
Isotopes
| Isotope | Atomic mass | Abundance (%) | Half life | Mode of decay |
| $^{14}$N | 14.003 | 99.636 | | |
| $^{15}$N | 15 | 0.364 | | |

## Pressure and Temperature Data

Molar heat capacity: 29.124 J mol$^{-1}$ K$^{-1}$

## See Also

* liquid nitrogen on Wikipedia
* isotropes of nitrogen on Wikipedia