Is N2 a Nonpolar or Polar Gas?

Have you ever tried dipping a flower in a chilly substance and shattering it like glass on a table? Liquid nitrogen was used. Even foods that can be stored for a long time were almost certainly preserved with nitrogen gas. However, when studying the molecular structure of N2, a rookie chemist may wonder if N2 is polar or nonpolar. To uncover the solution, let’s look into a few aspects of N2’s structure and reactivity.

Is N2 polar or nonpolar, then? Because of its linear geometrical structure, N2 is a nonpolar molecule that is also a diatomic molecule. As a result, both atoms have equal electronegativity and share an equal fraction of charge, resulting in a nonpolar molecule with a net-zero dipole moment.

Nitrogen, or N2, is a plentiful and essential molecule in biological and industrial processes. Nitrogen is found in compound form in all living things and makes up 78 percent of the air we breathe every day.

In industrial chemistry, nitrogen is abundant in fertilisers, dyes, nylon, and explosives. Any cleaning supplies containing ammonia, NH3, were most likely created with molecular nitrogen.

Electronegativity-based polarity

We can predict the level of polarity a molecule will have when atoms make bonds to form molecules. Ionic bonds transmit valence electrons entirely between atoms, resulting in a charge for both atoms.

When sodium (Na) binds with chlorine (Cl), for example, sodium gives up one of its valence electrons to chlorine, resulting in Na+ and Cl-, the most stable forms of these elements.

However, we’re talking about covalent bonds, which involve atoms sharing electrons. Covalent bonds are formed between nonmetals, and they can be polar or nonpolar.

When two atoms form covalent connections, electron density is transferred from one to the other. The electrons will not be shared equally if the atoms’ electronegativities are not equal, resulting in partly ionic charges on each atom.

The creation of hydrochloric acid, or HCl, is a fantastic illustration of this.

Electronegativities are usually available for the element you’re working with, so I’ll list them below. The electronegativity of hydrogen (H) is 2.1, while that of chlorine (Cl) is 3.0; the higher the electronegativity, the more negative an element will be when it is stable.

Chlorine has seven electrons and needs eight to complete its valence shell. Hydrogen has one valence electron and needs two to complete its valence shell. As a result, they’ll share their single electron and establish a covalent connection.

Because chlorine’s electronegativity is higher than that of hydrogen, it will take up more electron density.

Because of the increased electron density, chlorine will have a partial negative charge. Due to its lack of electron density, hydrogen develops a partial positive charge.

This produces a dipole moment, which causes the electron density to be directed toward the more electronegative molecule.

Because of the difference in electronegativities and a molecular dipole moment, a hydrochloric acid molecule will be polar.

Check out this article to learn more about HCl’s polarity.

N2 is a nonpolar molecule for a reason.

Let’s put this logic to the test using N2. The electronegativity of nitrogen atoms is around 3.04. However, nitrogen gas is a homonuclear molecule, which means it is made up of two identical atoms bound together.

The two nitrogen atoms would have the same electronegativity, which implies they would share electron density equally.

No dipole moment can occur if the electron density is divided equally between the two atoms. As a result, we can suppose N2 is nonpolar.

N2 Lewis structure

The valence, or outermost, electrons of a molecule are represented by a Lewis Structure, which is a very simple representation. It doesn’t explain the molecule’s geometry, but it’s a start toward understanding the geography.

However, the Lewis Structure can provide the best electron makeup of the molecule, revealing whether N2 is polar or nonpolar.

On the periodic table, nitrogen belongs to Group 5A, which means its outermost shell has five electrons. A single nitrogen atom’s Lewis structure is shown below.

Nitrogen, like most other elements on the periodic table, adheres to the octet rule, which states that it requires eight electrons in its outer shell.

As a result, it will look for additional atoms that want to complete the octet rule by sharing valence electrons. Ammonia, for example, is a chemical made up of one nitrogen molecule and three hydrogen atoms.

The purpose is to create electron pairs: there is already a pair of electrons or a lone pair at the top of the Lewis structure for a nitrogen atom, so they are not available for bonding.

The remaining three single electrons can be used to form covalent bonds, or bonds in which two atoms share electrons, with other atoms that have single electrons.

Nitrogen has three hydrogen atoms because hydrogen has one electron and only needs two electrons to complete its outer shell.

Nitrogen now has eight electrons surrounding it, one lone pair and three single bonds, as seen below.

The octet rule for nitrogen is now complete, and hydrogen now has the two electrons it need for a complete valence shell.

This leaves us with the Lewis structure of ammonia, which is the same as its molecular formula, NH3. The polarity of NH3 can be found in the article.

Let’s look at the molecular formula for nitrogen, N2. Nitrogen is a diatomic molecule, which implies that at room temperature and pressure (1 atm at 25°C), nitrogen atoms spontaneously connect with one another to meet the octet rule of both atoms.

Other diatomic molecules, such as oxygen, hydrogen, and the four halogens, are members of this family (fluorine, chlorine, iodine, and bromine). So, what exactly is the Lewis Structure of N2?

Remember that nitrogen has five valence electrons, two of which form a lone pair, thus they must complete the octet rule by binding their remaining three free electrons.

One electron from one nitrogen molecule will create a single bond with another electron from another nitrogen molecule, as indicated in the diagram above.

All three free electrons must form bonds in order for both nitrogen atoms to fulfil the octet rule, resulting in a triple bond. As a result, a nitrogen molecule with a triple bond exists in nature, making it low-energy and stable.

N2 Molecular Geometry

We may now look at the molecular geometry of N2 now that we’ve covered the Lewis structure.

The Lewis structure can usually anticipate the molecule’s structure, but it can also point us in the direction of the valence-shell electron-pair repulsion, or VSEPR theory.

The VSEPR hypothesis is based on the idea that the geometry of a molecule will reduce the repulsion between electrons in that atom’s valence shell.

Remember that electrons are negative and that, like magnets, if they go too close to one another, they repel each other, putting a pressure on the molecule. As a result, we’d like to keep the strain to a minimum.

We know that nitrogen gas is a diatomic molecule with only two atoms in its structure, as shown by the Lewis Structure.

According to VSEPR theory, N2 can only have a linear structure, or a straight line. This indicates that the two atoms are separated by 180 degrees, as shown below.

Linear molecules are usually nonpolar, but this isn’t always the case (see: hydrochloric acid, hydrofluoric acid, carbon monoxide), so we can’t just conclude N2 is nonpolar based on this.

To do so, we’ll need to delve a little more into electron density and electronegativity, which we’ve already examined.

You should also read the articles on N2 Lewis Structure and Molecular Geometry, as well as Hybridization, for a better understanding.

Conclusion

In our daily lives, we encounter a lot of nitrogen as a chemical. We can determine the polarity of a diatomic, homonuclear molecule by looking at its structure, geometry, and electron density.

We discovered that nitrogen gas forms a strong triple bond, has a linear geometry with 180° between nitrogen atoms, and equally shares its electron density among nitrogen atoms. As a result, we can say that nitrogen gas is nonpolar.

Read more: Is Cs2 a Polar or Nonpolar Substance

Misha Khatri
Misha Khatri is an emeritus professor in the University of Notre Dame's Department of Chemistry and Biochemistry. He graduated from Northern Illinois University with a BSc in Chemistry and Mathematics and a PhD in Physical Analytical Chemistry from the University of Utah.

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