Structure, Molecular Geometry, and Hybridization of NO3

NO3 is a polyatomic, negatively charged ion. Consequently, it is also known as nitrogen oxoanion. Nitrate is the scientific term for the substance generated when nitric acid loses a proton.

Nitrate is an essential nitrogen and oxygen source. It is utilised in agricultural farms as fertilisers (such as ammonium, salt, and potassium) to increase solubility and biodegradability. It also relieves heartache.

Nitrogen and oxygen are essential to an ecosystem consisting of vegetation and wildlife.

NO3 is readily soluble in water, but excessive concentrations in drinking water are hazardous to human health because they interfere with oxygen transport in the blood.

Gilbert N. Lewis, an American chemist, invented the concept of electron dot structure in 1916.

Following are rules for constructing the Lewis dot structure of any compound.

Follow the octet rule, which states that an atom’s outermost shell should have a total of 8 electrons. (Exceptions include the elements hydrogen and boron)

Calculate the total number of valence electrons in a compound based on the number of atoms present.

Then, determine the number of bonded and lone pairs. (Bonding pairs involve the quantity of electrons that contribute to bonding between atoms, whereas lone pairs consist of electrons that do not contribute to bonding)

After determining the core atom, surround it with the most electronegative atoms.

  1. Form a single bond and count the number of electrons involved.

Calculate the electron lone pair using the following formula.

Lone pairs electrons = Valence electrons – Bonding electrons

Assign the lone pairs to the terminal atoms and ensure that each atom has eight electrons in its last shell.

The atom at the centre must complete its octet. Create double or triple bonds based on the number of electrons present on the core atom.

Development of NO3 Lewis Dot Structure

There is one atom of nitrogen and three atoms of oxygen in the ion NO3. It has one negative charge as well.

In the periodic table, nitrogen and oxygen correspond to periods 5A and 6A, respectively. Therefore, oxygen has six valence electrons and nitrogen has five in their outer shells.

Observe the quantity of valence electrons.

Nitrogen: 5

Oxygen containing 3 atoms – 6 * 3 = 18

Due to the presence of a negative charge, an extra valence electron is added: 1

5 + 18 + 1 = 24 are total valence electrons

For an atom to occupy the centre position, it must be less electronegative. According to the periodic table, nitrogen is less electronegative than oxygen, hence it is the centre atom of the structure.

  1. Begin the nitrate’s frame dot structure by forming three single bonds between three oxygen and nitrogen atoms. There are 6 valence electrons used.
  2. Based on the above data, the structure has

bond pairs – three (6 electrons)

lone pairs – 9 pairings (18 electrons)

  1. To begin, finish the octet of the terminal atoms. Arrange the remaining 18 valence electrons such that each oxygen atom receives six valence electrons and three lone pairs are formed.

Upon observation, nitrogen has only six valence electrons. Remove two electrons from one of the oxygen atoms and convert a single bond into a double bond to complete its octet.

As depicted in the picture below, the structure results in two single bonds and one double bond between nitrogen and oxygen atoms.

What is an official fee?

Every atom has a formal charge somewhere. Formal charge is a crucial component of Lewis dot structure.

It maintains a trace of the electrons assuming that they are distributed equally throughout the atoms of the molecule. It is not concerned with the electronegativity of the atom, but rather represents the electron count.

If the atom has acquired an electron, it will have a negative charge, and if it has lost electrons, it will have a positive charge.

There are three distinct approaches to calculating the formal charge: a mathematical formula, a graphic, and intuition.

The statutory charge of NO3

To mathematically determine the formal charge of a single atom, the formula is

The formal charge (F.C) equals (Number of valence electrons) minus (Number of non-bonding pair electrons) minus (Number of bonding pair electrons / 2)

The F.C of oxygen forms a double bond with the nitrogen atom.

F.C = 6 – 4 – (4/2) = 0; therefore, this atom has no formal charge.

F.C. of an atom of nitrogen

F.C = 5 – 0 – (8/2) = 1, indicating that nitrogen has a positive formal charge.

F.C. of oxygen forming a single bond with an atom of nitrogen

F.C = 6 – 6 – (2/2) = -1, which indicates that both oxygen atoms in a single bond with nitrogen have a negative formal charge.

To compute the overall charge of the nitrate ion, a pair of positive and negative formal charges on the oxygen atom are cancelled, leaving a single negative formal charge.

Therefore, the formal charge of the ion is negative.

Combination of FO3

Hybridization is a method for determining the number of atoms linked to an atom’s central and lone pair. It explores the process of how atoms within molecules are positioned in three separate dimensions.

The most essential aspect of hybridization is determining the chemical configuration of a molecule formed by a () bond and a pi () bond.

The very first bond in a dot structure is always a sigma bond, while the second or third bond is a pi bond.

The VSEPR theory states that the number of bond pairs can be determined by calculating the number of sigma () bonds and lone pair of the centre atom, i.e. the steric number, which is the number of electron-dense regions surrounding the atom.

Since the steric number is three, there are three single sigma bonds and no lone pairs, which results in sp2 hybridization.

The structure itself demonstrates that three sp2 orbitals of nitrogen overlap with one oxygen 1s orbital. Oxygen’s 2p orbitals combine to form a lone pair.

The p orbital of nitrogen forms a covalent link with three oxygen atoms.

NO3 Molecular Geometry

The VSEPR theory leads you to the conclusion that NO3 is sp2-hybridized.

The model also asserts that the molecular architecture of the compound is trigonal planar, with each orbital equally spaced at 120 degrees (bond angle) on a plane.

A is the centre atom, X is the atom linked to A, (n) is the number of bonded atoms, and N is the number of nonbonding electron pairs, according to the formula AX(n) N.

AX is the formula if N is disregarded as there is no lone pair of electrons (3).

Therefore, the formula specifies the trigonal planar shape.

The trigonal planar form of the NO3 molecule generates symmetry across the NO bonds; as a result, the three dipoles created by the NO bonds cancel each other out, resulting in a dipole of zero for NO3.

Consequently, NO3 is a nonpolar molecule.


The nitrate ion has only a negative charge, thus high levels of nitrate in any environment source are hazardous.

  1. The nitrate ion is non-polar and has a net dipole moment of zero.

The periodic table is of tremendous assistance in determining the Lewis dot structure of NO3, as it provides information on the atomic numbers and electronegativity of the elements.

Read more: Structure, Molecular Geometry, and Hybridization of SO3.

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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