Nitrogen is a diatomic molecule, which means that it consists of two nitrogen atoms chemically bonded together. Its chemical formula is N2. 1
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Key Takeaways: Why is Nitrogen Diatomic?
- Nitrogen is a diatomic molecule, consisting of two nitrogen atoms chemically bonded together in a triple bond.
- Monatomic nitrogen (N) exists but is rare and highly reactive.
- Nitrogen atoms bond to form a diatomic molecule through a covalent bond by sharing electrons and forming a triple bond.
- The triple bond in nitrogen gas is very strong and stable, making it an unreactive substance that is often used as an inert gas.
Explanation: Why is nitrogen a diatomic molecule?
Nitrogen (N2) is a diatomic molecule because it has a very strong triple bond between the two nitrogen atoms. This bond is formed by the sharing of six electrons between the two atoms, which provides the molecule with a very high bond energy and stability. 2
The electronic configuration of nitrogen (atomic number 7) is 1s2 2s2 2p3, with five valence electrons in its outermost shell. To achieve a stable configuration, nitrogen needs to gain three electrons or lose five electrons, which is energetically unfavorable. 3
However, by sharing electrons with another nitrogen atom, both atoms can achieve a stable configuration with eight valence electrons (the octet rule). This sharing results in a triple bond between the two nitrogen atoms, which is the strongest bond found in any diatomic molecule.
The triple bond between the nitrogen atoms is very stable, requiring a large amount of energy to break it. This stability is why nitrogen gas is very unreactive and is often used as an inert gas in industrial applications. 4
Does monatomic nitrogen exist?
Yes, monatomic nitrogen, written as N, exists, but it is rare and highly reactive. It is formed when nitrogen gas (N2) is exposed to very high temperatures, such as in lightning strikes, nuclear explosions, or in high-temperature plasmas. 5
At room temperature and pressure, however, the vast majority of nitrogen exists as N2 molecules, which are much more stable than monatomic nitrogen.
This is because the triple bond between the nitrogen atoms in N2 provides a very high bond energy, which requires a large amount of energy to break.
Monatomic nitrogen is highly reactive because it only has five valence electrons, and it seeks to gain or lose an electron to achieve a more stable configuration. 6
As a result, monatomic nitrogen is often found in highly reactive compounds, such as nitrogen oxides (NOx) or ammonia (NH3).
How do nitrogen atoms bond to form a diatomic molecule?
Nitrogen atoms bond to form a diatomic molecule through a covalent bond. The two nitrogen atoms share electrons to form a strong triple bond, which holds the atoms together in the diatomic molecule, nitrogen gas (N2). 7
The bonding occurs through the overlapping of the outermost atomic orbitals of the two nitrogen atoms. Each nitrogen atom has five valence electrons, which are located in the 2p subshell.
When the atoms approach each other, the 2p orbitals of each atom overlap, forming three molecular orbitals – one bonding orbital and two antibonding orbitals.
The bonding orbital results from the constructive interference of the two 2p orbitals, which allows the two atoms to share a pair of electrons and form a covalent bond. This bonding orbital is lower in energy than the original atomic orbitals and is therefore more stable.
The two antibonding orbitals result from the destructive interference of the two 2p orbitals. These orbitals are higher in energy than the original atomic orbitals and are therefore less stable.
The resulting N2 molecule has a triple bond, consisting of one sigma bond and two pi bonds. The triple bond is very strong, requiring a large amount of energy to break. 8
This stability makes nitrogen gas a very unreactive substance, which is why it is often used as an inert gas.
Further reading
Why is Fluorine Diatomic?
Why is Bromine Diatomic?
Why is Oxygen Diatomic?
Is Sulfur Diatomic?
Why is Iodine Diatomic?
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References
- Holleigh Graminske, L. W. (n.d.). Nitrogen (Diatomic). Nitrogen (Diatomic). https://cms.gutow.uwosh.edu/gutow/Chem371_F19/HGLW/Jmol_Nitrogen_Animations/Jmol_Nitrogen_Animations.html
- Xu, L. T., & Dunning, T. H. (2016, June 22). Variations in the Nature of Triple Bonds: The N2, HCN, and HC2H Series. The Journal of Physical Chemistry A, 120(26), 4526–4533. https://doi.org/10.1021/acs.jpca.6b03631
- Electron Configuration for Nitrogen (N). (n.d.). Electron Configuration for Nitrogen (N). https://terpconnect.umd.edu/~wbreslyn/chemistry/electron-configurations/configurationNitrogen.html
- Gomollón-Bel, F. (2017, February 13). Secret of dinitrogen triple bond’s strength unpicked. Secret of Dinitrogen Triple Bond’s Strength Unpicked | Research | Chemistry World. https://www.chemistryworld.com/news/secret-of-dinitrogen-triple-bonds-strength-unpicked/2500387.article
- NSF.gov https://par.nsf.gov/servlets/purl/10315832
- Nitrogen – Wikipedia. (2019, January 27). Nitrogen – Wikipedia. https://en.wikipedia.org/wiki/Nitrogen
- Lewis Structure for N2 (Dinitrogen or Nitrogen Gas). (n.d.). Lewis Structure for N2 (Dinitrogen or Nitrogen Gas). https://terpconnect.umd.edu/~wbreslyn/chemistry/Lewis-Structures/lewis-structure-for-N2.html
- Nitrogen and Oxygen. (n.d.). Nitrogen and Oxygen. http://butane.chem.uiuc.edu/pshapley/genchem1/L9/2.html
