Geometry, Hybridization, and Polarity of NCl3 Lewis Structure

Nitrogen trichloride has the chemical formula NCl3. It’s also known as trichloramine, and it’s a yellow, oily halogen nitride with a strong odour. Because it is unstable in its pure state and sensitive to heat, shock, light, and any organic component, it is recognised as a powerful explosive.

It explains why nitrogen trichloride is immobile and must be manufactured on the spot anytime it is needed.

NH3 + 3 HOCl + NCl3 + 3 H2O

Nitrogen and chlorine gas are produced when nitrogen trichloride combines with water in the air. Both react with air gases to produce a series of explosive bursts that are difficult to put out.

The best technique to prevent nitrogen trichloride detonation is to use hot water or sunlight. There are several ways to make nitrogen trichloride, and not all of them are suitable for everyone.

The following are a few of the methods:

Chlorine forms nitrogen trichloride droplets when it combines with an ammonium salt.

When ammonia reacts with trichloroisocyanuric acid, chloramines are formed, which can be used to make trichloramine or nitrogen trichloride.

Nitrogen trichloride is produced via electrolysis of ammonium chloride.

Nitrogen Trichloride Lewis Structure (NCl3)

The Lewis structure is the first step in learning about a molecule’s physical and chemical properties.

Before drawing the Lewis structure for nitrogen trichloride, it is necessary to analyse the Lewis structures of the component atoms.

Nitrogen and chlorine have atomic numbers of 7 and 17, respectively. It gives them the following electronic configuration:

1s2 2s2 2p3 nitrogen

1s2 2s2 2p6 3s2 3p5 chlorine

It is apparent that the valence electrons in nitrogen and chlorine are 5 and 7, respectively. To complete their octet, nitrogen requires three extra valence electrons, while chlorine just requires one.

Let’s have a look at how to draw the Lewis structure of nitrogen trichloride:

Step 1: Count how many valence electrons are already present in one nitrogen trichoride molecule:

It’s 26 since 5 come from the nitrogen atom and 21 from three chlorine atoms.

Step 2: Calculate how many more valence electrons are needed to complete the octets in a single nitrogen trichloride molecule:

It’s six since the nitrogen atom requires three and each chlorine atom requires one. Because there are three chlorine atoms, they require a total of three valence electrons.

Step 3: Locate the main atom:

The centre atom is the atom that exists as a single entity. Furthermore, the centre atom is the element with the lowest electronegativity value, as it is required to form the most bonds.

As a result, nitrogen is the most important atom.

Step 4: Draw the skeleton in its most basic form: Place nitrogen in the middle and chlorine atoms on three sides of it.

Place available valence electrons in pairs around each atom and adjust their positions to complete each atom’s octet.

Step 5: Determine the type of bond that forms between the chemicals involved:

Because each chlorine atom only requires one valence electron whereas nitrogen requires three to complete its octets, it will be a single bond.

Step 6: This is the Lewis structure of nitrogen trichloride:

What are Valence Electrons, and what do they do?

We know that an atom’s structure is very similar to that of our solar system, with the nucleus at the centre and electrons orbiting in their own shell around it.

Each atom moves in its orbit due to a force of attraction exerted by the nucleus. Each shell has a smaller pull, with the outermost having the smallest. As a result, electrons at the outermost shell have the least pull and are more easily involved in bond formation.

Valence electrons are electrons that are found in the outermost shell.

It’s important to remember that valence electrons can also be found in the outer two or three shells. Valence electrons always follow the octet rule, which limits them to a maximum of eight.

Nitrogen Trichloride Molecular Geometry (NCl3)

Because it comprises three chlorine atoms bound to a single nitrogen atom with one lone pair of valence electrons, nitrogen trichloride is a tetratomic molecule.

It gives nitrogen trichloride a trigonal pyramidal molecular shape. The Valence Shell Electron Pair Repulsion (VSEPR) Theory can be used to investigate it further.

The nitrogen trichloride has a steric number of 4 and one lone pair of valence electrons, according to the article. Only a trigonal pyramidal form is acceptable for both criteria.

The number of atoms linked to the core atom and the number of lone pairs of electrons are added to get the steric number.

Furthermore, it is critical to recognise that the lone pair of electrons on the nitrogen atom give the molecule its bent conformation and reduce the bond angle from 120 degrees to 109.5 degrees.

Because no lone pair of electrons are present on any of the chlorine atoms, the lone pair of electrons exert pressure in the direction of the chlorine atoms, which is not counteracted.

The length of the link between nitrogen and chlorine is 1.759.

Nitrogen Trichloride Hybridization (NCl3)

Nitrogen The core atom of trichloride is nitrogen, with three chlorine atoms encircling it from three sides. As a result, its hybridization structure is AX3N, which corresponds to the central atom’s sp3 hybridization.

The single lone pair of electrons on the nitrogen atom is represented as N.

One 2s orbital and three 2p orbitals interact and intermix to form four new hybrid orbitals with identical energy levels for the nitrogen atom.

Two valence electrons acquire the 2s shell in the excited state, which corresponds to the lone pair of valence electrons. Furthermore, each of the 2p shells is occupied by the three left valence electrons.

The nitrogen trichloride molecule is made up of three single bonds, each of which connects nitrogen to one chlorine element.

Because single bonds can only be created via sigma bonds, there is no pi bond in the nitrogen trichloride molecule.

The molecule experiences sp3-sp3 head-on overlapping as a result of this and the position of orbitals in the nitrogen trichloride during the excited state.

It is the most powerful sort of bond formation, resulting in a structure that is extremely stable and not readily available for bond formation with any atom placed nearby.

Nitrogen Trichloride Polarity (NCl3)

Polarity refers to an atom’s capacity to attract a shared pair of valence electrons to form a bond and construct a new molecule.

Polarity is a property that occurs when an atom’s electric charge is separated, resulting in the production of one positive and one negative end.

When an atom with a shared pair of valence electrons comes into touch with another atom with a shared pair of valence electrons, it begins to behave like a magnet and generates either a strong force of attraction or repulsion.

Because their electronegativity values differ by more than 0.4, nitrogen trichloride is a polar molecule. Nitrogen and chlorine have electronegativity values of 3.04 and 3.16, respectively, with a difference of 0.12.

It’s vital to note that formal charge distribution on the nitrogen trichloride molecule cannot be used to confirm the polar behaviour of nitrogen trichloride.

Valence electrons – Unbonded electrons – 12 Bonded electrons = Formal charge


5 – 2 – 1/26 = 0 nitrogen

7- 6-1/22 = 0 Chlorine

As a result, the overall formal charge distribution on nitrogen trichloride is zero, indicating that it is a nonpolar molecule.

It is critical to understand that each molecule does not adhere to all of the polarity criteria.

The 0.6D dipole moment is caused by the existence of a lone pair of electrons on a nitrogen atom, which generates a dipole cloud on the molecule.

This dipole cloud forms on the nitrogen atom, implying that any future bond formation will occur through the nitrogen atom.

Let’s look at some nitrogen trichloride applications (NCl3)

NCl3’s Applications

It has the ability to act as a bleaching agent.

It is used as a flour for ageing.

It’s employed as a tearing agent.

It has the capability of being utilised as an immediate explosive.

To summarise!

The tetratomic molecule nitrogen trichloride possesses three sigma bonds and one lone pair of electrons. The molecule’s anomaly is caused by this lone pair of electrons, which manifests itself in the form of a reduced bond angle and polar behaviour.

When no new lone pair of electrons is available to neutralise the influence of an existing one, the overall structure of the molecule alters. The structure should have been trigonal planar in theory, but the lone pair of electrons transforms it into trigonal pyramidal in practise.

Because one 2s and three 2p orbitals mix to form new orbitals of similar energy, the hybridization of the nitrogen atom in nitrogen trichloride is sp3.

Read more: Is SiCl4 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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