Nitrogen [N]

Characteristics

An: 7 N: 7

Am: 14.0067 g/mol

Group No: 15

Group Name: Pnictogen

Block: p-block Period: 2

State: gas at 298 K

Colour: colourless Classification: Non-metallic

Boiling Point: 77.36K (-195.79^oC)

Melting Point: 63.05K (-210.1^oC)

Critical temperature: 126.2K (-146.9^oC)

Density: 1.251g/l

Discovery Information

Who: Daniel Rutherford

When: 1772

Where: Scotland/Sweden

Name Origin

Latin nitrogenium, where nitrum (from Greek nitron) means "native soda", and genes means "forming". "Nitrogen" in different languages.

Sources

Nitrogen can be made by liquification and then fractional distillation of the air. It is very easily done commercially. It can also be made by heating NaN3 to 300 degrees C.

Around 44 million tons are produced annually.

Abundance

Universe: 1000 ppm (by weight)

Sun: 1000 ppm (by weight)

Carbonaceous meteorite: 1400 ppm

Earth’s Crust: 25 ppm

Seawater: Atlantic surface: 8 x 10^-5 ppm; Atlantic deep: 2.7 x 10^-1 ppm; Pacific surface: 8 x 10^-5 ppm; Pacific deep: 5.4 x 10^-1 ppm

Human: 2.6 x 10⁷ ppb by weight; 1.2 x 10⁷ ppb by atoms

Uses

Nitrogen has many industrial uses in the gaseous forms, but probably the most interesting is liquid nitrogen, which is extremely cold. Items that must be frozen to extremely low temperatures for preservation are frequently stored in liquid nitrogen. Fertility clinics store sperm, eggs and embryos used to help infertile couples become pregnant in ampoules in liquid nitrogen. Since nitrogen gas is very stable, at standard temperature and pressure, it is used as the air in inert welding atmospheres. Documents, foods and chemicals are sometimes stored in nitrogen to keep them from oxidizing or reacting with air or water.

Notes

Nitrogen is the largest single component of the Earth’s atmosphere (78.084% by volume, 75.5% by weight).

Nitrogen in the elemental form was considered to be inert and was even named ozote which refers to the fact that it is not reactive. Of course nitrogen does form compounds, but the gaseous form consists of diamers (2 nitrogens bonded together). The diamer is very stable.

Nitrogen is a major element in organic compounds, especially proteins. Some nitrogen compounds are highly reactive. Trinitrotoluene is TNT or dynamite. Ammonium Nitrate is a fertilizer, but was used as the major explosive ingredient in the Oklahoma City bombing. Anfo, or Ammonium Nitrate and fuel oil mixture is the primary explosive used in the mining industry because it is inexpensive, easy to manufacture and can be easily manufactured near the mine site thus reducing the risks and expenses related to the transportation of explosives. Nitrates, Nitrites and Azides (all nitrogen compounds are either oxidizers or reactives and will react violently under the right conditions.

The triple bond in molecular nitrogen (N₂) is one of the strongest in nature. The resulting difficulty of converting (N₂) into other compounds, and the ease (and associated high energy release) of converting nitrogen compounds into elemental N₂, have dominated the role of nitrogen in both nature and human economic activities.

Hazards

Rapid release of nitrogen gas into an enclosed space can displace oxygen, and therefore represents an asphyxiation hazard. Nitrogen also dissolves in the bloodstream, and rapid decompression (particularly in the case of divers ascending too quickly) can lead to a potentially fatal condition called decompression sickness, when nitrogen bubbles form in the bloodstream. It can also cause nitrogen narcosis.

Nitrogen Compounds

Chloramine NH₂Cl

Commonly used in low concentrations as a disinfectant in municipal water systems as an alternative to chlorination. Water treated with chloramine lacks the distinct chlorine odour of the gaseous treatment and so has improved taste.

Aquarium owners must remove the chloramine from their tap water because it is toxic to fish. Many animals are sensitive to chloramine and it must be removed from water given to many animals in zoos.

Dinitrogen tetroxide N₂O₄

Dinitrogen tetroxide is one of the most important rocket propellants ever developed and by the late 1950s it became the storable oxidizer of choice for rockets in both the USA and USSR.

Nitric oxide NO : Irritant :

It is an important signaling molecule in the body of mammals including humans, one of the few gaseous signaling molecules known. It is also a toxic air pollutant produced by automobile engines and power plants.

The nitric oxide molecule is a free radical, which makes it very reactive and unstable. In air, it quickly reacts with oxygen to form the poisonous nitrogen dioxide (NO₂).

Nitric dioxide NO₂ : Highly Toxic :

It is one of several nitrogen oxides (Nox). This orange/brown gas has a characteristic sharp, biting odor. NO₂ is one of the most prominent air pollutants and a poison by inhalation.

Nitrogen trichloride NCl₃ : Explosive :

A yellow, oily, pungent-smelling liquid, often found as a byproduct of chemical reactions between nitrogen-containing compounds and chlorine.

Nitrogen trichloride is a very strong explosive; an explosion involving it blinded Sir Humphry Davy temporarily, and forced him to take on Michael Faraday as a worker. This was in part because some of Davy’s junior lab workers had recently been fired for fighting. Nitrogen trichloride is incredibly sensitive; it will explode upon exposure to cold or hot temperatures, sunlight, or organic substances such as turpentine.

Nitrogen triiodide NI₃

Also called nitrogen iodide, is a highly explosive compound of nitrogen and iodine. It is a contact explosive, and small quantities explode with a gunpowder-like snap when touched by even a feather, releasing a volatile cloud of iodine vapour.

Small amounts of nitrogen triiodide are sometimes synthesized as a demonstration to chemistry students. However, because the compound is so unstable, it has not been used in blasting caps or primers for explosives.

The reason for it’s instability is due to the size difference between the two different types of atoms. The three iodine atoms are much bigger than the nitrogen atom holding them together. Because of this, not only is the bond between nuclei under much stress and therefore weaker, but the outside electrons of the different iodine atoms are very close, which increases the overall instability of the molecule.

Nitrous oxide N₂O

Under room conditions, it is a colourless non-flammable gas, with a pleasant, slightly-sweet odour. It is used in surgery and dentistry for its anaesthetic and analgesic effects, where it is commonly known as laughing gas due to the euphoric effects of inhaling it. It is also used as an oxidizer in internal combustion engines. Nitrous oxide is present in the atmosphere where it acts as a powerful greenhouse gas.

The gas was discovered by Joseph Priestley in 1772, who called it phlogisticated nitrous air (see phlogiston). Humphry Davy in the 1790s tested the gas on himself and some of his friends, including the poets Samuel Taylor Coleridge and Robert Southey. They soon realised that nitrous oxide considerably dulled the sensation of pain, even if the inhaler were still semi-conscious. And so it came into use as an anaesthetic, particularly by dentists, who do not typically have access to the services of an anesthesiologist and who may benefit from a patient who can respond to verbal commands.

Urea phosphate CO(NH₂)₂H₃PO₄

It is made by reacting urea with phosphoric acid (H₃PO₄). It is sometimes used as a fertilizer.

Nitric acid HNO₃

Nitric acid, otherwise known as aqua fortis or spirit of nitre, is a colourless, corrosive liquid, a toxic acid which can cause severe burns. If the solution contains more than 86% nitric acid, it is referred to as fuming nitric acid, and can be separated into two kinds of fuming acids, white fuming nitric acid and red fuming nitric acid.

Commonly used as a laboratory reagent, nitric acid is used in the manufacture of explosives such as nitroglycerin, trinitrotoluene (TNT) and Cyclotrimethylenetrinitramine (RDX), as well as fertilizers such as ammonium nitrate.

It has additional uses in metallurgy and refining as it reacts with most metals, and in organic syntheses. When combined with hydrochloric acid, it forms aqua regia, one of the few reagents capable of dissolving gold and platinum.

Reactions of Nitrogen

Under normal conditions nitrogen will not react with air, water, halogens, acids or bases.

Occurrence of Nitrogen

Nitrogen is the largest single component of the Earth’s atmosphere (78.082% by volume of dry air, 75.3% by weight in dry air).

14N is created as part of the fusion processes in stars, and is estimated to be the 7th most abundant chemical element (by mass) in our universe.

Compounds that contain this element have been observed by astronomers, and molecular nitrogen has been detected in interstellar space by David Knauth and coworkers using the Far Ultraviolet Spectroscopic Explorer. Molecular nitrogen is a major constituent of Titan’s thick atmosphere, and occurs in trace amounts of other planetary atmospheres.

Nitrogen is present in all living tissues as proteins, nucleic acids and other molecules. It is a large component of animal waste (for example, guano), usually in the form of urea, uric acid, and compounds of these nitrogenous products.

Isotopes of Nitrogen

¹³N [6 neutrons]

Abundance: synthetic

Half life: 9.965 minutes [ Electron Capture ]

Decay Energy: 2.220 MeV

Decays to ¹³C.

¹⁴N [7 neutrons]

Abundance: 99.634%

Stable with 7 neutrons

¹⁵N [8 neutrons]

Abundance: 0.366%

Stable with 8 neutrons

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