Nitrogen (N) is a nonmetallic element in Group 15 [Va] of the periodic table. It is a colorless, odorless, tasteless gas and the most plentiful element in Earth's atmosphere. Nitrogen is a constituent of all living matter. Nitrogen's atomic number is 7, and its atomic weight is 14.0067. It has a melting point of -209.86 °C (-345.8 °F) and a boiling point of -195.8 °C (-320.4 °F). At 1 atm and 0° C, nitrogen has a density of 1.2506 grams/litre. Its usual oxidation states are -3, +3, +5, and its electron configuration is 1s22s22p3. The greatest amount of elemental nitrogen is used to manufacture nitrogen compounds, such as ammonia, nitric acid, and fertilizers.

Where is nitrogen found on Earth?

Nitrogen is found in several forms and locations on Earth: Atmosphere The Earth's atmosphere is approximately 78% nitrogen by volume, making it the primary source for industrial and commercial use. Various compounds Nitrogen can be found in ammonia and ammonium salts in the atmosphere. It is also in rain and soil, as well as in seawater as ammonium, nitrite, and nitrate ions. Mineral deposits Nitrogen occurs in mineral deposits of nitre or saltpetre (potassium nitrate) and Chile saltpetre (sodium nitrate), though these are not sufficient for human needs. Organic matter Nitrogen is a key component of proteins in living organisms. Fixed nitrogen Nitrogen is fixed in nature as nitric oxide by lightning and ultraviolet rays, but more significant amounts of nitrogen are fixed as ammonia, nitrites, and nitrates by soil microorganisms.

Why is nitrogen important for living things?

Nitrogen is vital for all living things because it is a key part of proteins and nucleic acids , which are essential for life on Earth. Although nitrogen is abundant in the atmosphere, most organisms can't use it in that form. To be used by plants and animals, nitrogen gas must be converted into other compounds through nitrogen fixation . Most nitrogen fixation is carried out by bacteria and blue-green algae, which convert nitrogen into ammonia, nitrates, and nitrites. Plants take up these compounds, and animals acquire them by eating plants or other animals.

What forms does nitrogen take in nature?

Nitrogen, essential for all life on Earth, exists in various forms in nature. As a gas, it makes up about 78% of Earth's atmosphere. However, plants and animals can't directly use this free nitrogen. Nitrogen fixation, carried out by bacteria and blue-green algae, converts nitrogen gas into reactive compounds like ammonia, nitrates, and nitrites, which are then taken up by plants. Animals obtain nitrogen by consuming plants or other animals. Decomposition of organic matter and waste products returns nitrogen to the soil as ammonia, which is further converted into nitrates. Denitrifying bacteria then convert nitrates back into atmospheric nitrogen, completing the nitrogen cycle .

How do plants use nitrogen from the environment?

Plants rely on nitrogen, an essential element, for their growth, maintenance, and reproduction. Although the atmosphere is 78% nitrogen, plants can't directly use it in that form. Plants acquire nitrogen from the soil through a process called nitrogen fixation . This is mainly carried out by microorganisms such as bacteria and blue-green algae that convert atmospheric nitrogen into inorganic compounds like ammonia, nitrites, and nitrates, which plants can then absorb and use. Symbiotic bacteria, like Rhizobium , form a close relationship with legumes, living in their root nodules and converting nitrogen to ammonia for the plant's development.

What is the nitrogen cycle and why is it important?

The nitrogen cycle is the process by which nitrogen circulates through the environment in various forms. It is essential because nitrogen is a key component of proteins and nucleic acids, which are necessary for life on Earth. The cycle consists of: * Nitrogen fixation Conversion of nitrogen gas to ammonia. * Nitrification Transformation of ammonia into nitrates. * Assimilation Absorption of nitrates and ammonia into plant tissues. * Ammonification Decomposition of organic matter into ammonia. * Denitrification Conversion of nitrates into atmospheric nitrogen. Nitrogen-fixing bacteria perform 90% of nitrogen fixation, playing an important role in the nitrogen cycle. Without the nitrogen cycle, Earth's supply of nitrogen would accumulate in the oceans.

nitrogen

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A labeled diagram of a periodic table entry for nitrogen shows its atomic number 7, symbol N, electron configuration, atomic weight, and name. Symbols indicate nitrogen is a nonmetal gas at room temperature, has a hexagonal crystal structure, and strongly acidic higher-valence oxides. A key explains the diagram's icons and color coding.

Explore an interactive periodic table of the elements

A scientific graph plots average nuclear binding energy per nucleon (in MeV) against atomic mass number, showing a sharp rise at low mass numbers, peaking near iron (Fe), then gradually declining for heavier elements. Key isotopes are labeled along the curve.

Figure 12: Transformations of nitrogen compounds in the atmosphere.

Diagram of the Bohr atomic model for a nitrogen atom, showing a central nucleus with protons and neutrons, surrounded by two rings of orbiting electrons. Labels identify protons, neutrons, electrons, and electron orbits.

A chemical diagram illustrates the stepwise formation of organometallic ruthenium clusters, showing how one ruthenium atom is added at each stage to build increasingly complex structures, with arrows indicating the addition of Ru(CO)5 and loss of CO molecules.

Diagram illustrating the nitrogen cycle, showing how nitrogen moves between the atmosphere, biosphere, and soil through natural processes like nitrogen fixation, assimilation, ammonification, nitrification, and denitrification, as well as through human activities such as fertilizer use and industrial emissions. Blue arrows indicate natural activities, and red arrows indicate human activities.

A vertical temperature scale shows the cryogenic region, highlighted from absolute zero up to about 90 kelvin, with key points where gases like oxygen, nitrogen, hydrogen, and helium liquefy, alongside temperature conversions between kelvin, Celsius, Fahrenheit, and Rankine.

The importance of nitrogen and phosphorus in ecosystems

At a Glance

nitrogen summary

nitrogen

chemical element

Also known as: N, azote

Written by

R. Thomas Sanderson

Fact-checked by

Britannica Editors

Last updated

Oct. 10, 2026 •History

Top Questions

What is nitrogen?
Nitrogen (N) is a nonmetallic element in Group 15 [Va] of the periodic table. It is a colorless, odorless, tasteless gas and the most plentiful element in Earth's atmosphere. Nitrogen is a constituent of all living matter.

Nitrogen's atomic number is 7, and its atomic weight is 14.0067. It has a melting point of -209.86 °C (-345.8 °F) and a boiling point of -195.8 °C (-320.4 °F). At 1 atm and 0° C, nitrogen has a density of 1.2506 grams/litre. Its usual oxidation states are -3, +3, +5, and its electron configuration is 1s22s22p3.

The greatest amount of elemental nitrogen is used to manufacture nitrogen compounds, such as ammonia, nitric acid, and fertilizers.
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Where is nitrogen found on Earth?
Nitrogen is found in several forms and locations on Earth:
- Atmosphere The Earth's atmosphere is approximately 78% nitrogen by volume, making it the primary source for industrial and commercial use.
- Various compounds Nitrogen can be found in ammonia and ammonium salts in the atmosphere. It is also in rain and soil, as well as in seawater as ammonium, nitrite, and nitrate ions.
- Mineral deposits Nitrogen occurs in mineral deposits of nitre or saltpetre (potassium nitrate) and Chile saltpetre (sodium nitrate), though these are not sufficient for human needs.
- Organic matter Nitrogen is a key component of proteins in living organisms.
- Fixed nitrogen Nitrogen is fixed in nature as nitric oxide by lightning and ultraviolet rays, but more significant amounts of nitrogen are fixed as ammonia, nitrites, and nitrates by soil microorganisms.
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Why is nitrogen important for living things?
Nitrogen is vital for all living things because it is a key part of proteins and nucleic acids, which are essential for life on Earth. Although nitrogen is abundant in the atmosphere, most organisms can't use it in that form.

To be used by plants and animals, nitrogen gas must be converted into other compounds through nitrogen fixation. Most nitrogen fixation is carried out by bacteria and blue-green algae, which convert nitrogen into ammonia, nitrates, and nitrites. Plants take up these compounds, and animals acquire them by eating plants or other animals.
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What forms does nitrogen take in nature?
Nitrogen, essential for all life on Earth, exists in various forms in nature. As a gas, it makes up about 78% of Earth's atmosphere. However, plants and animals can't directly use this free nitrogen.

Nitrogen fixation, carried out by bacteria and blue-green algae, converts nitrogen gas into reactive compounds like ammonia, nitrates, and nitrites, which are then taken up by plants. Animals obtain nitrogen by consuming plants or other animals. Decomposition of organic matter and waste products returns nitrogen to the soil as ammonia, which is further converted into nitrates. Denitrifying bacteria then convert nitrates back into atmospheric nitrogen, completing the nitrogen cycle.
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How do plants use nitrogen from the environment?
Plants rely on nitrogen, an essential element, for their growth, maintenance, and reproduction. Although the atmosphere is 78% nitrogen, plants can't directly use it in that form.

Plants acquire nitrogen from the soil through a process called nitrogen fixation. This is mainly carried out by microorganisms such as bacteria and blue-green algae that convert atmospheric nitrogen into inorganic compounds like ammonia, nitrites, and nitrates, which plants can then absorb and use. Symbiotic bacteria, like Rhizobium, form a close relationship with legumes, living in their root nodules and converting nitrogen to ammonia for the plant's development.
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Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.
What is the nitrogen cycle and why is it important?
The nitrogen cycle is the process by which nitrogen circulates through the environment in various forms. It is essential because nitrogen is a key component of proteins and nucleic acids, which are necessary for life on Earth.

The cycle consists of:
* Nitrogen fixation Conversion of nitrogen gas to ammonia.
* Nitrification Transformation of ammonia into nitrates.
* Assimilation Absorption of nitrates and ammonia into plant tissues.
* Ammonification Decomposition of organic matter into ammonia.
* Denitrification Conversion of nitrates into atmospheric nitrogen.

Nitrogen-fixing bacteria perform 90% of nitrogen fixation, playing an important role in the nitrogen cycle. Without the nitrogen cycle, Earth's supply of nitrogen would accumulate in the oceans.
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nitrogen (N), nonmetallic element of Group 15 [Va] of the periodic table. It is a colourless, odourless, tasteless gas that is the most plentiful element in Earth’s atmosphere and is a constituent of all living matter.

Element Properties
atomic number	7
atomic weight	14.0067
melting point	−209.86 °C (−345.8 °F)
boiling point	−195.8 °C (−320.4 °F)
density (1 atm, 0° C)	1.2506 grams/litre
usual oxidation states	−3, +3, +5
electron configuration	1s²2s²2p³

History

About four-fifths of Earth’s atmosphere is nitrogen, which was isolated and recognized as a specific substance during early investigations of the air. Carl Wilhelm Scheele, a Swedish chemist, showed in 1772 that air is a mixture of two gases, one of which he called “fire air,” because it supported combustion, and the other “foul air,” because it was left after the “fire air” had been used up. The “fire air” was, of course, oxygen and the “foul air” nitrogen. At about the same time, nitrogen also was recognized by a Scottish botanist, Daniel Rutherford (who was the first to publish his findings), by the British chemist Henry Cavendish, and by the British clergyman and scientist Joseph Priestley, who, with Scheele, is given credit for the discovery of oxygen. Later work showed the new gas to be a constituent of nitre, a common name for potassium nitrate (KNO₃), and, accordingly, it was named nitrogen by the French chemist Jean-Antoine-Claude Chaptal in 1790. Nitrogen first was considered a chemical element by Antoine-Laurent Lavoisier, whose explanation of the role of oxygen in combustion eventually overthrew the phlogiston theory, an erroneous view of combustion that became popular in the early 18th century. The inability of nitrogen to support life (Greek: zoe) led Lavoisier to name it azote, still the French equivalent of nitrogen.

Occurrence and distribution

Among the elements, nitrogen ranks sixth in cosmic abundance. The atmosphere of Earth consists of 75.51 percent by weight (or 78.09 percent by volume) of nitrogen; this is the principal source of nitrogen for commerce and industry. The atmosphere also contains varying small amounts of ammonia and ammonium salts, as well as nitrogen oxides and nitric acid (the latter substances being formed in electrical storms and in the internal combustion engine). Free nitrogen is found in many meteorites; in gases of volcanoes, mines, and some mineral springs; in the Sun; and in some stars and nebulae.

Nitrogen also occurs in mineral deposits of nitre or saltpetre (potassium nitrate, KNO₃) and Chile saltpetre (sodium nitrate, NaNO₃), but these deposits exist in quantities that are wholly inadequate for human needs. Another material rich in nitrogen is guano, found in bat caves and in dry places frequented by birds. In combination, nitrogen is found in the rain and soil as ammonia and ammonium salts and in seawater as ammonium (NH₄⁺), nitrite (NO₂⁻), and nitrate (NO₃⁻) ions. Nitrogen constitutes on the average about 16 percent by weight of the complex organic compounds known as proteins, present in all living organisms. The natural abundance of nitrogen in Earth’s crust is 0.3 part per 1,000. The cosmic abundance—the estimated total abundance in the universe—is between three and seven atoms per atom of silicon, which is taken as the standard.

Concept artwork on the periodic table of elements.

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India, Russia, the United States, Trinidad and Tobago, and Ukraine were the top five producers of nitrogen (in the form of ammonia) in the early 21st century.

Commercial production and uses

Commercial production of nitrogen is largely by fractional distillation of liquefied air. The boiling temperature of nitrogen is −195.8 °C (−320.4 °F), about 13 °C (−23 °F) below that of oxygen, which is therefore left behind. Nitrogen can also be produced on a large scale by burning carbon or hydrocarbons in air and separating the resulting carbon dioxide and water from the residual nitrogen. On a small scale, pure nitrogen is made by heating barium azide, Ba(N₃)₂. Various laboratory reactions that yield nitrogen include heating ammonium nitrite (NH₄NO₂) solutions, oxidation of ammonia by bromine water, and oxidation of ammonia by hot cupric oxide. Chemical equations.

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Elemental nitrogen can be used as an inert atmosphere for reactions requiring the exclusion of oxygen and moisture. In the liquid state, nitrogen has valuable cryogenic applications; except for the gases hydrogen, methane, carbon monoxide, fluorine, and oxygen, practically all chemical substances have negligible vapour pressures at the boiling point of nitrogen and exist, therefore, as crystalline solids at that temperature.

In the chemical industry, nitrogen is used as a preventive of oxidation or other deterioration of a product, as an inert diluent of a reactive gas, as a carrier to remove heat or chemicals and as an inhibitor of fire or explosions. In the food industry nitrogen gas is employed to prevent spoilage through oxidation, mold, or insects, and liquid nitrogen is used for freeze drying and for refrigeration systems. In the electrical industry nitrogen is used to prevent oxidation and other chemical reactions, to pressurize cable jackets, and to shield motors. Nitrogen finds application in the metals industry in welding, soldering, and brazing, where it helps prevent oxidation, carburization, and decarburization. As a nonreactive gas, nitrogen is employed to make foamed—or expanded—rubber, plastics, and elastomers, to serve as a propellant gas for aerosol cans, and to pressurize liquid propellants for reaction jets. In medicine rapid freezing with liquid nitrogen may be used to preserve blood, bone marrow, tissue, bacteria, and semen. Liquid nitrogen has also proven useful in cryogenic research.