Structure, Geometry, and Hybridization of NH3 Lewis

NH3 denotes the chemical formula for ammonia, which is the simplest binary hydride composed of nitrogen and hydrogen. All atoms are covalently linked to achieve a reactive state in this stable pnictogen hydride. Ammonia is lighter than air, odourless, and has no colour.

It is a frequent nitrogenous waste produced by aquatic creatures and a vital nutritional component for terrestrial animals. In addition, ammonia is regarded both corrosive and dangerous when stored in much larger volumes.

The lewis structure, also known as an electron dot structure, is primarily a graphical representation of an atom’s valence electrons.

The diagram is created by encircling atom symbols with numerous pairs of dots. In addition, the lines indicate the formation of bonds between atoms, with the number of lines indicating whether a single, double, or triple bond has been created.

In addition, the lewis structure can be utilised to determine the presence of a pair of electrons that are not participating in the creation of a bond. Atomic symbols are filled with electrons in accordance with the octet rule.

This graphic depicts the Lewis Structure of a single atom of nitrogen and hydrogen.

Nitrogen has an atomic number of seven, making its electronic configuration 1s2 2s2 2p3. As the p shell can only host a maximum of six electrons, three electrons are scarce.

The result is that a single nitrogen atom has five valence electrons. In addition, the hydrogen atom has an atomic number of one, and its electronic configuration is 1s1.

As the s shell requires two electrons, there is a shortage of one electron. Consequently, the hydrogen atom typically possesses one valence electron.

What do valence electrons consist of?

valence electrons refer to the number of electrons present in the outermost shell of an atom, i.e. free electrons. These valence electrons participate in bond formation by absorbing valence electrons from another atom or by contributing valence electrons themselves.

As each atom strives to attain a stable state by completing its octet, the valence electrons behave largely in this manner.

In addition, since the outermost shell of the atom has the weakest hold on the nucleus due to its extreme distance, the valence electrons react to the presence of surrounding valence electrons.

NH3 Octet Rule

The maximum number of valence electrons that can be drawn around the symbol of an atom, according to the octet rule, is eight.

The Lewis structure of NH3 satisfies and balances the lack of one valence electron in each hydrogen atom (total of three hydrogen atoms) and three valence electrons in the nitrogen atom.

NH3 Lewis Structure

The Lewis structure of an atom of nitrogen and an atom of hydrogen reveals a total of eight valence electrons participating in bond formation to make a single NH3 molecule with four atoms.

Here, we must investigate the Lewis structure of the NH3 molecule:

Check the number of total valence electrons: It takes eight NH3 molecules to make one molecule.

Find the total number of electrons required: According to the octet rule, six ammonia (NH3) molecules equal one molecule. 1 Nitrogen atom requires 3 electrons and all three Hydrogen atoms require 1 additional electron to be stable.

Determine the total number of bonds that are forming: There are three individual covalent connections between every oxygen and hydrogen atom.

Determine the core atom: Nitrogen will serve as the primary atom.

Draw the following Lewis diagram:

Structure Geometrical of Ammonia (NH3)

The binding angle between the hydrogen, nitrogen, and hydrogen atoms is 107°. It is evident that the geometric structure of NH3 would be deformed.

It is explained using the Valence Shell Electron Pair Repulsion (VSEPR) theory, which states that the presence of a lone pair on the nitrogen atom causes the entire structure of NH3 to be curved, resulting in a bond angle of 107 degrees.

The optimal bond angle for the bent geometrical diagram is 109.5°, which may come as a surprise.

Ammonia’s (NH3) molecular geometry is trigonal pyramidal or deformed tetrahedral. Due to the presence of a single pair of non-bonding, lone electrons on the nitrogen atom, which repel the bonding orbitals.

Observe that the majority of non-bonding, lone pairs of electrons are located at the apex.

Therefore, the pressure imposed by the lone pair of electrons’ repulsion impacts the nitrogen-hydrogen atom (N-H) bond on the other side.

It reduces the bond angle from 109.5 degrees to 107 degrees.

Due to its initial pyramidal form, ammonia is polar in nature because its atoms have uneven charges. Examine the informative article that has already been written about the polarity of ammonia.

Molecular Hybridization of Ammonia (NH3)

Each covalent link between nitrogen and hydrogen atoms consists of just sigma () bonds and no pi () bonds.

Pi () bonds are only present in double or triple bonds, whereas ammonia (NH3) only possesses single bonds.

Sigma () bonds are the most stable and robust of all covalent bonds. Nevertheless, the existence of a single electron pair at the apex makes all the difference.

The nitrogen hybridization in ammonia (NH3) is sp3. It can be seen from the graphical representation of hybridization in NH3 that the nitrogen atom contains one 2s orbital and three 2p orbitals that combine and overlap to form four hybrid orbitals with equal energy.

Three bonding hybrid orbitals and one non-bonding hybrid orbital contribute to the ammonia’s sp3 hybridization (NH3).

The illustration of orbital overlap in the ammonia (NH3) molecule.

The bond-forming orbitals of NH3 undergo sp3 hybridization.

Molecular orbital diagram of ammonia (NH3) molecule

The molecular orbital diagram is a graphical illustration of how chemical bonding inside molecules occurs.

In the instance of ammonia (NH3), the molecular orbital diagram assists in comprehending the formation of sigma bonds.

Moreover, it assists in figuring out how the lone pair of electrons affect the overall structure and energy distribution of the molecule.

The s orbital of the three hydrogen atoms is utilised from sigma, together with anti-bonding combinations of the 1s orbitals of hydrogen and the sp3 orbitals of nitrogen.

In addition, orbitals of nitrogen with the same energy generate both bonding and antibonding interactions.

Nitrogen’s higher energy orbital reacts with the lower energy orbital’s bonding orbital to form non-bonding orbitals.

It is noteworthy to note that a single NH3 molecule exhibits 75% p orbital features and 25% s orbital characteristics.

This is because p orbitals are more energetically active during bond formation than s orbitals.


The Lewis structure of the NH3 molecule consists of three single sigma bonds between the nitrogen and hydrogen atoms. In addition, the bent geometrical structure of the NH3 molecule is caused by the presence of a single pair of lone electrons on the nitrogen atom.

This is the reason why the bond angle is 107° rather than 109.5°. In addition, the hybridization of ammonia (NH3) is sp3 due to the overlap of three p orbitals and one s orbital, which produces four hybrid orbitals with identical energies.

Read more: MO Diagram, NF3 Lewis Structure, Molecular Geometry, Hybridization, and Polarization

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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