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Nitrogen – Properties, Occurrence, Uses, Effects

  • Last Updated : 29 Nov, 2021

Nitrogen is a chemical element with the symbol N and the atomic number 7. In 1772, a Scottish physician named Daniel Rutherford was the first to discover and isolate it.

Nitrogen is the lightest element in group 15, often known as the pnictogens. 

It is a common element in the universe, with an estimated total abundance of around eight in the Milky Way and Solar System. The most common uncombined element is dinitrogen, which accounts for 78% of the Earth’s atmosphere. Nitrogen is found in all species, especially in amino acids (and hence proteins), nucleic acids (DNA and RNA), and adenosine triphosphate, an energy transfer molecule. After oxygen, carbon, and hydrogen, nitrogen is the fourth most prevalent element in the human body, accounting for around 3% of its mass. The nitrogen cycle describes how nitrogen moves from the atmosphere to the biosphere and organic molecules before returning to the atmosphere.

Properties of Nitrogen 

  1. Nitrogen is a colourless, odourless gas that can also be used as a liquid.
  2. The element is found in the form of N2.
  3. Because of its high bond energy, molecular nitrogen’s activation energy for the reaction is typically very high, making it relatively inert to most reagents under normal conditions.
  4. Furthermore, the nitrogen molecule’s extraordinary thermodynamic stability contributes greatly to the thermodynamic instability of many nitrogen compounds, whose bonds, while strong, are significantly weaker than those of molecular nitrogen. Nitrogen molecules can act as ligands in complicated coordination compounds.
  5. The electrical structure of a nitrogen atom is given by 1s2 2s2 2p3.
  6. The nuclear charge is poorly screened by the five outer shell electrons, resulting in a relatively large effective nuclear charge felt at the covalent radius distance. As a result, nitrogen atoms are small in size and have high electronegativity, falling somewhere between carbon and oxygen in terms of both of these characteristics.

Occurrence of Nitrogen 

The most prevalent pure element on the planet is nitrogen. Despite this, it is not prevalent in the Earth’s crust, accounting for only 19 ppm. The atmosphere and living beings constantly exchange nitrogen molecules. Fixing nitrogen into a plant-useable form, usually, ammonia is the initial step. Some nitrogen fixation is accomplished by lightning strikes that produce nitrogen oxides, but the majority is accomplished by diazotrophic bacteria using nitrogenases enzymes. Plants use ammonia to produce proteins when it is taken up by them. The nitrogen molecules in these plants are then digested by animals, who utilise them to create proteins and excrete nitrogen-bearing faeces. Finally, these organisms die and degrade, exposing free dinitrogen to the atmosphere through bacterial and environmental oxidation and denitrification.

Although excess nitrogen–bearing waste, when leached, causes eutrophication of freshwater and the establishment of marine dead zones, as nitrogen-driven bacterial growth depletes water oxygen to the point that all higher creatures die, the Haber process is generally utilised as a fertiliser. Furthermore, the nitrous oxide produced during denitrification depletes the ozone layer in the atmosphere.

To protect themselves from the severe osmotic effects of their environment, many saltwater fish produce huge levels of trimethylamine oxide; the conversion of this chemical to dimethylamine is what causes the early stench in saltwater fish. The fast interaction of nitric oxide with water in mammals produces the metabolite nitrite. Animal nitrogen metabolism in proteins results in the excretion of urea, whereas animal nucleic acid metabolism results in the excretion of urea and uric acid. The formation of long-chain, nitrogen-containing amines, such as putrescine and cadaverine, which are breakdown products of the amino acids ornithine and lysine, respectively, in decaying proteins, causes the unmistakable odour of animal flesh decay.

Uses of Nitrogen 

  • It’s used to make ammonia, then to make nitric acid, which is then utilised as a fertiliser.
  • Potassium nitrate, ammonium nitrate, and nitric acid are all examples of nitric acid salts. Nitro glycerine and other nitrated organic compounds are common explosives.
  • Liquid nitrogen is used as a refrigerant in the transportation and freezing of food. Liquid nitrogen is also used to preserve bodies and reproductive cells, as well as to keep biological samples stable. A cryogenic liquid is a liquid nitrogen. It may be transported and stored with minimal evaporative loss when properly insulated in containers like dewar flasks.
  • Some construction equipment makes use of compressed nitrogen gas to assist the hydraulic system in providing more power to devices like hydraulic hammers. The breakdown of sodium azide produces nitrogen gas, which is used to inflate airbags.
  • Soil contains a lot of nitrogen molecules. Nitrogen can be found in the form of nitrates and nitrites in both water and soil. These molecules are all part of the nitrogen cycle, which is linked to the carbon cycle.
  • For inert gas asphyxiation, nitrogen gas has become the preferred inert gas.
  • When the oxygen in the air would cause a fire, explosion, or oxidising hazard, the gas is employed as an inert atmosphere.

Nitrogen in the environment

Nitrogen molecules are mostly found in the air. Nitrogen is found in the form of nitrates and nitrites in water and soil. The nitrogen cycle encompasses all of these elements, and they are all interrelated. Humans have drastically altered natural nitrate and nitrite proportions, owing primarily to the use of nitrate-containing manures. 

Industrial firms produce a lot of nitrogen, which leads to an increase in nitrate and nitrite supplies in soil and water as a result of nitrogen cycle reactions. As a result, nitrate concentrations in drinking water will skyrocket.

Environmental effects of nitrogen

Humans have drastically altered natural nitrate and nitrate sources. The widespread use of fertilisers is the primary source of nitrates and nitrites. Due to the release of nitrogen oxides, which can be converted to nitrates and nitrites in the environment, combustion operations can also improve nitrate and nitrite supplies. 

Nitrates and nitrites are also produced during the manufacturing of chemicals and are utilised as food preservatives. The nitrogen concentration in groundwater and surface water, as well as nitrogen in food, rises dramatically as a result of this. Due to the susceptibility of specific organisms to the effects of nitrogen compounds, the addition of nitrogen bonds to the environment might modify the composition of species.

Sample Questions

Question 1: Where is nitrogen found?


It is the universe’s fifth most plentiful element, accounting for around 78 percent of the earth’s atmosphere and containing an estimated 4,000 trillion tonnes of gas. Fractional distillation is a method of extracting nitrogen from liquefied air.

Question 2: What are nitrogen tanks used for?


Nitrogen is utilised to avoid oxidation and to create a safe, inert environment that sweeps away furnace-generated gases. This can also be used as a laser cutting aid steam to make plasma cutting easier. Nitrogen is employed in a wide range of upstream and midstream electrical applications.

Question 3: What would happen if nitrogen-fixing bacteria did not exist?


Bacteria convert nitrogen and carbon dioxide in the air into useful components that plants and animals can use as building blocks. To living beings, the loss of all microorganisms would be devastating news since they would no longer be able to create or obtain necessary nutrients on their own.

Question 4: How is nitrogen fixed?


In the soil, a diverse group of microorganisms known as diazotrophs, including bacteria like Azotobacter and archaea, naturally fix nitrogen. Certain plant families have symbiotic relationships with nitrogen-fixing bacteria, particularly legumes.

Question 5: How does nitrogen occur in the environment?


The majority of nitrogen molecules are present in the atmosphere. In water and soil, nitrogen is found in the form of nitrates and nitrites.

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