Nitrogen: Introduction, Occurrence, Properties, Uses, and Isotopes


Nitrogen is the seventh element of the periodic table located in group 15.

  • Nitrogen has 7 electrons.
  • Nitrogen has atomic number 7 whereas its atomic weight is 14.
Naming and History

The French chemist, Antoine Lavoisier named nitrogen “azote” which means ‘without life’. Nitrogen got its name from the Greek word “nitro” from niter meaning saltpeter and “genes” meaning ‘forming’. Thus, nitrogen is saltpeter forming.

The discovery of nitrogen is credited to various scientists. English physician, John Mayow in 1674, by combusting part of air demonstrated that air is composed of more than one element.

Joseph Black also studied air. He further assigned this to his student Rutherford. In 1772, Rutherford experimented by removing all oxygen and carbon content from the air. Then he tried to burn air but the air was not combusted. He then reported the presence of another element he named ‘noxious air’.

Carl Scheele also performed experiments by removing oxygen with the help of sulfur and iron filings and by burning phosphorus. He reported there is a gas that makes two-third and three-quarters of the original volume of air.

He named this gas ‘spent air’ and published his findings in 1777.

Occurrence of Nitrogen

The Earth’s air is composed of 78% of nitrogen. It is also the component of some minerals such as saltpeter. In soil, it is present in the form of nitrites and nitrates.


Properties of Nitrogen

Nitrogen is non-metal and in its pure elemental form, it is colorless, tasteless, odorless diatomic gas. It is an inert gas and like other members of its group, nitrogen is a poor conductor of current and heat.

The melting point of nitrogen is -210.00°C and its boiling point is -195.79°C. The density of nitrogen is 0.0012506 grams per cubic centimeter. Nitrogen is involved in the formation of the beautiful coloration of aurora lights.

Nitrogen in Biological Systems

Nitrogen is essential to all life forms. It is the part of nucleic acids, DNA, and proteins. Hence, it is an important part of the genetic code. Plants possess nitrogen mostly in the form of nitrites and nitrates.

Some bacteria fix nitrogen and help plants to absorb this. All this process of fixation is called the nitrogen cycle which is very important for maintaining balance in an ecosystem. For the needs of plants, it is used in fertilizers.

But excess nitrogen can cause soil leaching. In high amount, it also promotes algal bloom which in turn cause deficiency of oxygen in the water due to the high rate of photosynthesis in algae. Thus, are the cause of death of numerous aquatic species.

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Uses of Nitrogen

The greatest commercial use of nitrogen is as a part in the manufacture of ammonia by Haber process, consequently utilized as fertilizer and to produce nitric acid.

Liquid nitrogen (typically described as LN2) is utilized as a refrigerant for freezing and transporting food products, for the conservation of biological specimens such as reproductive cells (sperm and eggs), and for the storage of biological samples.

Nitrogen is used as an inert replacement for air where oxidation is unfavorable.

Nitrogen gas is mostly inert and is used as a protective shield in the semiconductor industry and throughout specific types of welding and soldering operations.

Oil companies utilize high-pressure nitrogen to assist force crude oil to the surface area.


There are two naturally occurring isotopes of nitrogen: Nitrogen- 14 and Nitrogen- 15. Nitrogen also has radioisotopes which are Nitrogen- 12, Nitrogen- 13, Nitrogen- 16, and Nitrogen- 17.

Nitrogen- 14 is abundant of all and makes up 99% of all nitrogen. It has many practical uses in the fields of agriculture, food, biochemicals and used in research works.

Nitrogen- 15 has importance in medical research and preservation. It has wide use in brain study, MRI and NMR (Nuclear Magnetic Resonance) techniques. In research works, it is used to label different specimens such as proteins.


  • What is the atomic number of nitrogen?
    • A) 6
    • B) 7
    • C) 14
    • D) 15
    • Answer: B
  • Who named nitrogen “azote” and what does it mean?
    • A) Antoine Lavoisier; “with life”
    • B) John Mayow; “without life”
    • C) Carl Scheele; “saltpeter forming”
    • D) Joseph Black; “forming”
    • Answer: A
  • What is the percentage composition of nitrogen in the Earth’s air?
    • A) 21%
    • B) 50%
    • C) 78%
    • D) 90%
    • Answer: C
  • At what temperature does nitrogen boil?
    • A) -210.00°C
    • B) -195.79°C
    • C) 0°C
    • D) 100°C
    • Answer: B
  • What is the primary commercial use of nitrogen?
    • A) Manufacturing oxygen
    • B) Production of nitrous oxide
    • C) Haber process for ammonia production
    • D) Making nitrogen fertilizers
    • Answer: C
  • Which form of nitrogen is essential for plants and is used in fertilizers?
    • A) Nitrogen gas
    • B) Nitrites
    • C) Nitrates
    • D) Ammonia
    • Answer: C
  • In what form is nitrogen primarily present in plants?
    • A) Nitrogen gas
    • B) Nitrites
    • C) Nitrates
    • D) Ammonia
    • Answer: C
  • What is the main component of Earth’s air apart from nitrogen?
    • A) Oxygen
    • B) Carbon dioxide
    • C) Argon
    • D) Hydrogen
    • Answer: A
  • Which isotopes of nitrogen are naturally occurring?
    • A) Nitrogen-10 and Nitrogen-11
    • B) Nitrogen-13 and Nitrogen-14
    • C) Nitrogen-14 and Nitrogen-15
    • D) Nitrogen-16 and Nitrogen-17
    • Answer: C
  • What is the significance of the “nitrogen cycle” in ecosystems?
    • A) It regulates nitrogen gas concentration in the atmosphere
    • B) It enhances nitrogen content in soil
    • C) It maintains balance in ecosystems by recycling nitrogen
    • D) It prevents excess nitrogen in water bodies
    • Answer: C
  • How is liquid nitrogen commonly used?
    • A) As a fuel for vehicles
    • B) As a refrigerant and for preserving biological specimens
    • C) In agriculture as a fertilizer
    • D) In medical surgeries
    • Answer: B
  • What is the primary role of nitrogen gas in the semiconductor industry?
    • A) As a fuel for machinery
    • B) As a refrigerant
    • C) As an inert protective shield
    • D) In the production of fertilizers
    • Answer: C
  • Which is the most abundant isotope of nitrogen?
    • A) Nitrogen-12
    • B) Nitrogen-13
    • C) Nitrogen-14
    • D) Nitrogen-15
    • Answer: C
  • What is the primary application of Nitrogen-15 in medical research?
    • A) Treatment of diseases
    • B) Brain study, MRI, and NMR techniques
    • C) Fertilizer production
    • D) Preservation of food
    • Answer: B
  • What is the importance of Nitrogen-14 in research works?
    • A) It is used as a radioactive isotope
    • B) It has no practical use
    • C) It is widely used in agriculture
    • D) It is used in various biochemical and research applications
    • Answer: D
  • What is the primary use of Nitrogen-15 in research works?
    • A) Labeling proteins in brain studies
    • B) As a fuel for rockets
    • C) In the production of fertilizers
    • D) In the synthesis of pharmaceuticals
    • Answer: A
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Summary: Nitrogen

This comprehensive tutorial delves into various aspects of nitrogen, the seventh element in the periodic table, with a focus on its introduction, historical naming, occurrence, properties, biological significance, uses, and isotopes.

  • Introduction:
    • Nitrogen, located in group 15, has atomic number 7 and atomic weight 14. It is a non-metal with 7 electrons.
  • Naming and History:
    • Antoine Lavoisier named it “azote,” meaning ‘without life,’ while its name derives from the Greek words “nitro” (saltpeter) and “genes” (‘forming’), emphasizing its role in saltpeter formation. Its discovery involved contributions from John Mayow, Joseph Black, and Carl Scheele.
  • Occurrence of Nitrogen:
    • Nitrogen constitutes 78% of Earth’s air and is found in minerals like saltpeter. In soil, it exists as nitrites and nitrates.
  • Properties of Nitrogen:
    • As a colorless, tasteless, and odorless diatomic gas, nitrogen is inert and a poor conductor of current and heat. It has a melting point of -210.00°C, boiling point of -195.79°C, and a density of 0.0012506 grams per cubic centimeter. Nitrogen contributes to the beautiful coloration of aurora lights.
  • Nitrogen in Biological Systems:
    • Essential to life, nitrogen is a component of nucleic acids, DNA, and proteins. The nitrogen cycle, involving bacteria, helps maintain ecosystem balance. However, excess nitrogen can lead to soil leaching and algal blooms, causing harm to aquatic species.
  • Uses of Nitrogen:
    • The primary commercial use is in the manufacture of ammonia via the Haber process for fertilizers and nitric acid. Liquid nitrogen is used for freezing and transporting food, preserving biological specimens, and in the semiconductor industry. It serves as a protective shield in welding, soldering, and oil companies use it to extract crude oil.
  • Isotopes:
    • Nitrogen has two naturally occurring isotopes, Nitrogen-14 (99% abundance) and Nitrogen-15. Nitrogen-14 finds extensive applications in agriculture, food, and biochemical fields, while Nitrogen-15 is crucial in medical research, brain studies, MRI, NMR techniques, and labeling proteins in research.
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This tutorial provides a thorough exploration of nitrogen’s multifaceted characteristics, emphasizing its role in various fields and its crucial significance in biological and industrial processes.