Nitrogen (N)

Nitrogen (Azote) is a chemical element with atomic number 7 in the periodic table. It’s the most abundant element on Earth. Nitrogen naturally occurs in the Earth’s atmosphere, crust, mantle, core, as well as in oceans. In Earth’s crust, this substance is present in the form of a liquid metal, while in the atmosphere nitrogen and its compounds occur in the form of a gas. 

Being a member of the nitrogen family of periodic table elements, this pnictogen has three valence electrons that help nitrogen make numerous compounds with the other chemical elements. Nitrogen has a wide application in medicine, pharmacy, and many industrial branches. Like oxygen, carbon, and hydrogen, nitrogen gas (N) is one of the elements that support life on Earth and makes it possible. 

Chemical and Physical Properties of Nitrogen

Symbol of NitrogenN
Atomic number7
Group of NitrogenNon-Metal
Crystal Structure of NitrogenHexagonal
Atomic weight (mass)14.00674
Shells of Nitrogen2,5
Orbitals of Nitrogen[He] 2s2 2p3
Valence of Nitrogen3,5
ColorA colorless nonmetal gaseous substance
Physical stateA gas at room temperature
Half-lifeFrom around 200 yoctoseconds to 9.965 minutes
Electronegativity according to Pauling3.04
Density0.0012506 g/cm³
Melting point63.18
Boiling point77.35
Van der Waals radius0.092 nm
Ionic radius1.71 (-3) Å
Covalent Radius of Nitrogen0.75 Å
Atomic Radius of Nitrogen0.75 Å
Atomic Volume of Nitrogen17.3 cm³/mol
Name Origin of NitrogenGreek: nitron and genes, (soda forming)
Discovered ByDaniel Rutherford
Pronounced of NitrogenNYE-treh-gen
Oxydation States of Nitrogen(±3),5,4,±2,±1
Uses of NitrogenPrimarily to produce ammonia and other fertilizers. Also used in making nitric acid, which is used in explosives. Also used in welding and enhanced oil recovery
Description of NitrogenColorless, odorless, tasteless gas; pale blue liquid. Third most abundant element in the universe. It is the most abundant element in the earth’s crust, and makes up almost 21% of the atmosphere

With the periodic table symbol N, atomic number 7, atomic mass of 14.0067 g.mol-1, and electron configuration [He] 2s22p3, nitrogen is a volatile, colorless, odorless, and tasteless diatomic gas. It reaches its boiling point at -195.8°C, while the melting point is achieved at -210°C. This member of the nitrogen family of elements has an electronegativity of 3.0 according to Pauling, whereas the atomic radius according to van der Waals is 0.092 nm. 

The nitrogen-nitrogen triple bond in N2 molecules is one of the strongest molecular bonds in chemistry. The N-N triple bond between the nitrogen atoms releases enormous energy and assigns the explosive properties of nitrogen when this gaseous substance is formed as a result of various chemical reactions. In addition, the explosive properties are most characteristic for the NOx compounds, or nitrogen oxides.        

In its liquified form, nitrogen possesses strong cryogenic properties. Liquid nitrogen (LN2) is colorless, odorless, nonflammable, and extremely cold substance. It boils at 77 K (−195.8° C or −320.4° F). When the liquid nitrogen boils, it displays the Leidenfrost effect. Namely, liquid nitrogen reaches its boiling point so fast that it envelops the surrounding surfaces with an insulating layer of nitrogen gas. 

How Was Nitrogen Discovered?

The chemical element nitrogen is considered to be one of the key components for understanding how the universe and life on our planet have been formed. The scientific evidence gives sufficient proof that nitrogen has been around even before the formation of the planets in our solar system, i.e. even before life itself.  

According to the Royal Society of Chemistry, this chemical element was produced in ancient Egypt by heating a mixture of animal excrement, urine, and salt. The result was nitrogen in the form of ammonium chloride (NH4Cl). 

The Contribution of John Mayow (1641 – 1679)

In 1674, the English chemist, physician, and physiologist John Mayow was intrigued by the nature of air and respiration. In his opinion as a scientist, Mayow believed that the air is not a single element, but a mixture of several other components. Eager to provide scientific evidence on this claim, Mayow conducted a series of experiments that proved that a part of the compound comprising the air was combustible, while the other constituting elements were not reacting in such a volatile manner. 

The Contribution of Joseph Black (1728 – 1799)

A century later, the Scottish physicist and chemist who discovered carbon dioxide, Joseph Black, tried to bring closure to the question raised by John Mayow – is there really more than just air? He continued the work of his English colleague by conducting more elaborate experiments. First, Black removed the carbon dioxide and oxygen from the compound, but part of it remained. 

At this point, the Scottish chemist asked his doctoral student Daniel Rutherford to finish what he started. Some of the most distinguished chemists like Scheele, Cavendish, Rutherford, and Priestley were also working on the ‘burnt’ or ‘dephlogisticated air’ in the same period. 

The Discovery of Daniel Rutherford (1749 – 1819)

Eager to contribute to the study of air, physician Daniel Rutherford started his experiment in 1772 by trapping a mouse into an enclosed space. When there was no more air left, the mouse died. Then, Rutherford put a lit candle in the space with no air. The candle flame also went out. Upon the third trial, Rutherford used burning phosphorus as a part of the oxygen removal process. After a while, the phosphorus was also extinguished without having enough oxygen to flame it. 

Next, Rutherford removed the carbon dioxide by the means of a solution that absorbed it. The resulting leftover from the experiment was an extremely unpleasant smelling phlogisticated part of the air, the nitrogen (N).  

The Discovery of Carl Scheele (1742 – 1786)

By conducting independent research on the air components, the German and Swedish Pomeranian pharmaceutical chemist Carl Sheele attempted to absorb the oxygen in several ways in the same year as Rutherford. Sheele’s chemical trials also led him to the discovery of nitrogen, which he called ‘a spent air’ due to the process of oxygen reduction which left the nitrogen as a residue. 

The First Liquefaction of Nitrogen

Polish physicists Zygmunt Wróblewski and Karol Olszewski were the first scientists who changed the aggregate state of nitrogen from gas to liquid. Nitrogen was first liquefied on April 15, 1883. 

How Did Nitrogen Get Its Name?

The name of element 7 originates from the Greek words ‘nitron‘ and ‘genes‘, meaning ‘formation of nitre (saltpeter)’. 

In 1790,  the French chemist Jean-Antoine-Claude Chaptal chose the name ‘nitrogen’ for the new element, because the scientific evidence showed that nitrogen was one of the constituting components of nitre (potassium nitrate). 

The French chemist Antoine Laurent Lavoisier (1743 – 1794) additionally named nitrogen as ‘azote’, meaning ‘without life’. 

Where Can You Find Nitrogen?

Nitrogen is the 7th most abundant chemical element in both the solar system and our galaxy. It has occurred as a result of the fusion reaction between hydrogen and carbon in supernova explosions of the old stars. Nitrogen’s gaseous compounds can be found in the atmospheres of moons and planets with atmospheres, as well as in the trails of comets and the Sun.

The Birth of Nitrogen in the Universe

According to a study conducted by Dennis Harries, Peter Hoppe, and Falko Langenhorst, the nitrogen that occurs on the Earth is not the same as the isotopes of nitrogen found in the Sun and the other celestial objects. In order to find an answer to their dilemma, this team of scientists applied transmission electron microscopy and secondary ion mass spectrometry techniques in order to examine a meteorite sample. As a result, they found a mineral labeled as carlsbergite in the meteorite’s structure. 

By analyzing the properties of this mineral, the team of scientists came to the conclusion that the carlsberg has been formed by a chemical reaction with a chromium-bearing metal exposed to reactive ammonia. On the other hand, the ammonia that had participated in the formation of the mineral was produced by melting of the ice in the protoplanetary disk, which had been triggered by a shock-wave activity in the early Sun. 

Harries, Hoppe, and Langenhorst assume that this is the same activity that has led to the formation of the planets and our solar system, which brings us to the fact that the chemical element nitrogen exists since the birth of our Universe. 

To continue with, they propose that nitrogen has been spread to the other parts of the universe by the planet Jupiter during the Grand Tack. As maintained by the Grand Tack model, our solar system has been formed by the migration of the giant planets, such as Jupiter and Saturn.

The Nitrogen Cycle

The nitrogen distribution to Earth and other planets in the solar system has been governed by biological and geological cycles. During the course of the biological cycle, nitrogen is taken from the atmosphere and used by nitrogen-fixing bacteria. This chemical element is responsible for the control of both amount and nature of biomass in the water and earth environment. Released in the form of NH4+, N2, or oxidized to nitrate, the nitrogen waste from the aforementioned bacteria is returned to the oceans and the atmosphere. 

As a part of the food chains, the nitrogen gas first has to be converted by the nitrifying bacteria in order for the plants and animals to absorb the nitrogen gas. During the nitrogen fixation process, the following chemical reaction is activated:

N2 + 3 H2 -> 2 NH3

By this process, nitrogen is converted into ammonia and ammonium by cyanobacteria. By this conversion, the plants become able to absorb the nitrogen from ammonia. 

Next, the nitrification process takes place:

2 NH3 + 3O2 – > 2 NO2 + 2 H+ + 2 H2O

2 NO2 + O2 -> 2 NO3

During this process, the aerobic bacteria convert further the ammonia and ammonium by using oxygen. First, the nitrogen gas is converted to nitrite (NO2) by the nitrosomonas bacteria, after which the nitrobacter converts the nitrite to a plant nutrient, i.e. nitrate (NO3). In the course of the assimilation process, the plants absorb ammonium and nitrate. This process is followed by the conversion of these nitrogen compounds into nitrogen-containing organic molecules, such as DNA and amino acids.

As for the animals, they absorb the nitrogen nutrients by feeding on the plants that have passed through the aforementioned processes. 

The nitrogen nutrients undergo the process of ammonification after they serve their purpose in both animals and plants. This process reverses the conversion process and turns back the nitrogen nutrients into ammonia and water-soluble ammonium salts. From this point, the anaerobic bacteria continue to reverse the conversion and the nitrogen nutrients become atmospheric nitrogen again during the process of denitrification

In this way, the biological cycle provides nitrogen for the geological formations which further release this chemical element in the Earth’s core, in the oceans, as well as in the atmosphere via N2 degassing. The nitrogen transport is also conducted via silicate melt (magma), water-rich fluids, or as a trace component in silicate minerals. In the silicate minerals, such as mica, wadsleyite, feldspar, garnet, bridgmanite, and clay minerals, nitrogen mostly occurs in the form of NH4+. The pure, elemental form of nitrogen is also found in graphite and diamond. 

Nitrogen in Everyday Life

As an industrial gas, nitrogen is produced by the method of fractional distillation of liquid air. The nitrogen gas used for commercial purposes is mostly derived as a byproduct of air-processing for an industrial concentration of oxygen. It has a wide application in many industries, as well as in everyday life.  

  • Nitrogen gas is used mainly in the production of ammonia which is later used for making explosives, nitrogen fertilizers, and nitric acid (HNO3). Ammonia is also used as refrigerant gas and in air-conditioning equipment, purification of water supplies, manufacturing of fabrics, pesticides, dyes, etc;
  • Manufacturing of electronic parts such as integrated circuits, diodes, and transistors also require nitrogen as one of the main components in the process;
  • This chemical element finds application in stainless steel production;
  • It’s also used as a freshness preserving agent of bulk and packaged foods;
  • A carbon dioxide and nitrogen mixture is used to add carbon dioxide to beer;
  • Hydrazine derivatives and hydrazine are applied as monopropellants and used in the process of rocket fuel production;
  • Nitroglycerin (glyceryl trinitrate) is a powerful substance able to release enormous energy. Due to this property, it’s used for making explosives, such as dynamite. 
  • The super-strong triple bond that nitrogen forms is used for making cyanoacrylate glue (the “super glue”). 
  • Ammonium nitrate (NH4NO3) is predominantly used as a high-nitrogen fertilizer in agriculture;
  • Liquid nitrogen is used for rapid freezing of biological samples and organic material, such as blood, bone marrow, tissue, bacteria, and semen in order to preserve them;
  • As a nutrient, nitrogen is essential for plant and animal growth, as well as for their nourishment;
  • Saltpeter, or potassium nitrate, is used as one of the gunpowder components;
  • Molecular gastronomy uses liquid nitrogen for the preparation of creative and visually unusual dishes and beverages.

Nitrogen and Health

Nitrogen is one of the main constituents of all living organisms on our planet. Being an essential component of the building blocks of life (DNA, RNA, and proteins), this chemical element is also a part of our genetic code. As every single cell contains nitrogen, this chemical is the fourth most abundant element in the human body. Also, ammonia and the ammonium ion are vital components of the metabolic processes in the human body.

Element 7 is also one of the chief components of the molecules in every major drug class in pharmacology and medicine, including antibiotics and neurotransmitters. 

Liquid nitrogen, nitroglycerine, and collodion are the nitrogen forms that are often used in various branches of medicine. 

Medical Liquid Nitrogen 

The liquid aggregate form of nitrogen is a cryogenic fluid. For commercial uses, it’s produced the fractional distillation of liquid air. This form of nitrogen is used as a part of cryotherapy in order to remove skin abnormalities, such as warts and skin lesions. Its cryogenic properties are also used to preserve biological samples at a very low temperature. 

Nitroglycerin (Medicine) C3H5(ONO2)3

An ester of nitric acid, nitroglycerine is widely used in cardiology for its effects on blood pressure. The medicine prevents many cardiovascular diseases, such as angina pectoris (chest pain) or coronary artery disease, by widening and relaxing the blood vessels. It doesn’t relieve the chest pain after it occurs. 

In its pure form, nitroglycerin is an oily, colorless, and somewhat sweet in taste substance. By adding glycerol to a mixture of concentrated nitric and sulfuric acids, the Italian chemist Ascanio Sobrero was the first scientist who prepared this nitrogen compound in 1846. 

Important: This article is for informative purposes only. Please consult your doctor or health practitioner prior to any health concerns. 


The solution of nitrocellulose in ether and alcohol is labeled as collodion. This nitrogen compound is used in medicine as a surgical dressing or for gluing the electrodes onto the patient’s scalp during the EEG imaging (an electrophysiological monitoring method that records the electrical activity of the brain). 

(Since collodion glues tightly and shrinks when applied to the skin, it’s also used in the theater make-up for recreating scars.)

Nitrogen in Food

Nitrogen-rich foods are converted into carbs by our body’s metabolism, rather than in fat. This makes this type of food a great choice for the weight-watchers and sportsmen. Since nitrogen is a key building block for amino acids, the logical conclusion is that high-protein foods may be just the right choice when it comes to food as a rich source of nitrogen.

The list of nitrogen-rich contains the following recommendations:

  • Soybeans and Soy Products;
  • Beans;
  • Nuts and Seeds;
  • Meat;
  • Poultry;
  • Fish and Shellfish;
  • Eggs;
  • Leafy Greens;
  • Green Herbs;
  • Rhubarb;
  • Fennel;
  • Beetroot;
  • Spirulina;
  • Protein Powders;
  • Antioxidant Rich Foods.

On the other hand, we also take nitrites and nitrites via food. These nitrogen compounds are known to have a negative health effect by triggering mutation of cells that may lead to cancer. So, it’s strongly advisable to avoid or limit the intake of foods with chemical preservatives, and processed meat (Bologna, salami, corned beef, ham, hot dogs, and sausages). 

How Dangerous Is Nitrogen?

Since nitrogen is an odorless, colorless, tasteless substance, its potentially toxic and hazardous presence cannot be easily detected. The New York Department of Health, United States, claims that most people are exposed to ammonia by inhaling the nitrogen gas or its vapors. 

While the pure elemental form of nitrogen is not considered to be toxic, liquid nitrogen has been identified as a highly flammable and harmful chemical substance, identified with the UN number 1,977.

Liquid Nitrogen Health Hazard

Liquid nitrogen can also cause severe frostbite upon contact with skin or any other tissue, asphyxiation (oxygen deprivation), and impose a risk of chemical explosion or explosion under pressure. Ingested liquid nitrogen damages the tissues in contact by expanding (in its gaseous form), as well as causing cold contact burns. 

Ammonia Health Hazard

Furthermore, exposure to high levels of ammonia in the air may cause severe irritation of the eyes, throat, skin, and lungs. The affected individuals typically experience coughing and burning sensation that may leave open wounds on the tissue which had been in contact with ammonium.

Nitrates, Nitrosamines and Nitrites Health Hazard

High nitrogen uptake, especially in the form of nitrates, nitrosamines, and nitrites, may lead to adverse health effects, such as:

  • Vitamin A deficiency;
  • Dysfunctionality of the thyroid gland;
  • Fashioning of nitro amines (leading to the formation of tumorous tissues and cancer);
  • Decreased oxygen transport among the cells.

According to FDA (U.S. Food and Drug Administration), nitrosamines are labeled as some of the strongest carcinogenic compounds. We are exposed to these organic compounds every day via our drinking water and foods such as meat, vegetables, and dairy products. A person with a daily intake of nitrosamines lower than the recommended value is not expected to have an increased risk of cancer.

Environmental Effects of Nitrogen

Nitrogen gas molecules naturally occur in the air, while the soil and waters contain this chemical element in the form of nitrites and nitrates. All of these nitrogen forms are part of the natural nitrogen cycle. As such, they do not impose any environmental or health hazards. The problem occurs with the industrial forms of nitrogen.

According to the U.S. Environmental Protection Agency (EPA), nutrient pollution caused by excess nitrogen and phosphorus in the air and water is one of the most widespread, costly, and challenging environmental problems. 

Nitrogen and Water

Ammonia, nitrite, and nitrate can trigger deterioration of water quality. In turn, these nitrogen compounds have a severe toxic effect upon the organisms living in the contaminated waters, such as fish and shrimp. 

Nitrogen Dioxide (NO2)

Nitrogen dioxide (NO2) a poisonous gas with a characteristic deep red-orange color. As one of the components of smog, this nitrogen compound is one of the most frequently occurring air pollutants in urban areas.  At high concentrations, nitrogen dioxide is highly toxic and may cause lung damage, as well as contribute to environmental pollution. 

Isotopes of Nitrogen

Naturally occurring nitrogen is a mixture of two isotopes, 14N (with a natural abundance of 99.6%) and 15N (with a natural abundance of 0.4%). All of the other nitrogen forms are radioactive and extremely short-lived. 

While most of the isotopes below 14 decay to carbon, the isotopes above the atomic mass of 15 decay to oxygen isotopes. With a half-life of 9.965 minutes, the nitrogen-13 isotope is the longest living form of nitrogen.


[n 1]

ZNIsotopic mass (Da)[3]

[n 2][n 3]


[resonance width]



[n 4]



[n 5]

Spin and


[n 6][n 7]

Natural abundance (mole fraction)
Excitation energyNormal proportionRange of variation
10N7310.04165(43)200(140)×10−24 s

[2.3(16) MeV]



11N7411.02609(5)550(20)×10−24 s

[1.58(+75−52) MeV]



11mN740(60) keV690(80)×10−24 s  1/2−  
12N7512.0186132(11)11.000(16) msβ+ (96.5%)12


β+, α (3.5%)8


[n 8]

13N[n 9]7613.00573861(29)9.965(4) minβ+13


14N[n 10]7714.00307400446(21)Stable1+0.99636(20)0.99579–0.99654
16N7916.0061019(25)7.13(2) sβ (99.99855%)16


β, α (.00145%)12


16mN120.42(12) keV5.25(6) µsIT (99.9996%)16


β (0.0004%)16


17N71017.008449(16)4.173(4) sβ, n (95.0%)16


β (4.9975%)17


β, α (.0025%)13


18N71118.014078(20)619.2(19) msβ (80.8%)18


β, α (12.2%)14


β, n (7.0%)17


19N71219.017022(18)336(3) msβ (58.2%)19


β, n (41.8%)18


20N71320.02337(8)136(3) msβ (57.1%)20O   
β, n (42.9%)19O
21N71421.02709(14)84(7) msβ, n (90.5%)20O(1/2−)  
β (9.5%)21O
22N71522.03410(22)23(3) msβ (54%)22O0−#  
β, n (34%)21O
β, 2n (12%)20O
23N71623.03942(45)13.9(14) ms


−15 ms]

β (50%)23O1/2−#  
β, n (42%)22O
β, 2n (8%)21O
24N71724.05039(43)#<52 nsn23N   
25N71825.06010(54)#<260 ns  1/2−#  

Source: Wikipedia

Nitrogen Compounds

Nitrogen is the element that forms the most compounds among all other elements of the periodic table. It occurs in both inorganic (e.g., ammonia, nitrate) and organic (e.g., amino and nucleic acids) forms. Most of the nitrogen compounds result from the reactions of ammonia, hydrogen cyanide, cyanogen, and nitrous or nitric acid. Typically, nitrogen adopts the oxidation state of +3 as a part of a compound. 

The reaction between nitric acid and an organic compound is called nitration. When nitrates explode or burn, they form a triple bond. In this way, nitrates produce great energy. On the other hand, nitrides show a stable electron structure of the atomic nucleus when exposed to extremely reducing conditions that resemble the early planetary formation processes.


The list of most common nitrates contains the following items:

Nitrate Ester

A nitrate ester is an organic functional group of nitric acid and alcohols. Nitroglycerin, collodium, and nitrocellulose are the nitrate esters with the widest application among the other items listed below:

  • Acetyl nitrate
  • 1,2,4-Butanetriol trinitrate
  • Collodion
  • Diethylene glycol dinitrate
  • Erythritol tetranitrate
  • Ethylene glycol dinitrate
  • Isosorbide dinitrate
  • Isosorbide mononitrate
  • Itramin tosilate
  • Mannitol hexanitrate
  • Naproxcinod
  • Nicorandil
  • Nipradilol
  • Nitrocellulose
  • Nitroglycerin
  • Nitromemantine
  • 3-Nitrooxypropanol
  • Pentaerythritol tetranitrate
  • Peroxyacetyl nitrate
  • Polyvinyl nitrate
  • Propatylnitrate
  • Propylene glycol dinitrate
  • Tenitramine
  • Triethylene glycol dinitrate
  • Trimethylolethane trinitrate
  • Trolnitrate
  • Xylitol pentanitrate

Ammonia (NH3)

Ammonia is a colorless gas with a distinct pungent odor, made up of one nitrogen and three hydrogen atoms. This chemical compound is the main neutral hydride of nitrogen. 

NH3 represents a building-block chemical of many household and gardening products for everyday use, such as cleaning products and ammonium nitrate fertilizers used for stimulation of plant growth. It’s produced by the Haber process (also: Haber-Bosh process). 

What is a Haber Process?

The Haber process refers to an industrial methodology of ammonia production from nitrogen and hydrogen. During this process, an iron catalyst at high temperature and pressure is used to pump nitrogen (extracted from the air) and hydrogen exposed to heat of 450°C, after which they pass through a tank containing an iron catalyst. The reaction that produces ammonia from these two gasses is a reversible one. 

Amines, amino acids, and amides are nitrogen compounds that are either related to or derived from ammonia.

Dinitrogen monoxide (N2O) 

Dinitrogen monoxide (N2O) is a colorless and relatively inert anesthetic gas. Also labeled as the laughing gas, this nitrous oxide can lead to feelings of euphoria upon inhalation. By slowing down the responses of both the brain and the body, dinitrogen monoxide triggers relaxation and fits of giggles and laughter – the most notable effects which have been tagged to the name of the nitrogen compound. 

Since this gas can cause throat spasms and inhibit breathing, it’s considered a highly hazardous substance, despite its catchy name. Classified as a psychoactive drug that is illegal to be supplied for its psychoactive effect, dinitrogen monoxide and inhalation of the ‘laughing gas’ may also bring about feelings of paranoia, hallucinations, dizziness, headache, nerve damage, and suffocation. 

5 Interesting Facts and Explanations

  1. The term pnictogen refers to any member of the nitrogen family, i.e. group 15 of the periodic table. There are two nonmetal elements (one gas, one solid), two metalloids, one metal, and one element with unknown chemical properties in this group: nitrogen, phosphorus, arsenic, antimony, bismuth, and probably moscovium. 
  2. The liquefied gases that reach their boiling point below -150 C (-238 F) are labeled as cryogenic liquids. Upon vaporization, all cryogenic liquids release large amounts of gas.     
  3. This chemical element gives the vivid rainbow colors of the aurora by emitting blue and red light at multiple wavelengths. 
  4. When we take a deep breath, almost 78 percent of the air we inhale is nitrogen. 
  5. The amount of nitrogen in a chemical substance can be determined by the Kjeldahl method