HNO3 Lewis Structure, Molecular Geometry, Hybridization, and MOT


Nitric acid (HNO3) acts as an oxidizing agent in the manufacturing of nylon. The strongest oxidizing agent, nitric acid, widely known as engraver’s acid, targets all metals with the obvious exceptions of gold and platinum. It is among the few strong acids that wholly dissociate when dissolved in water. It seems to have a pH equivalent to 3.01.

This article is all about in-depth information about the hno3 Lewis structure, molecular geometry, shape, hybridization, bond angle, MO diagram, and physiochemical characteristics of the Nitric acid (HNO3) molecule is explored in this blog post.

The nitric acid (HNO3) seems to have a freezing point of 42 °C and a boiling temperature of 83 °C. It is a routine laboratory reagent and an industrial chemical used in the production of a variety of polymers, explosives, and fertilizers.

Nitric acid is a STRONG OXIDIZER that promotes the ignition of other compounds even if it is not combustible itself.

Facts About HNO3

Another name for nitric acid is “spirit of nitre.” Nearly 68 % of the nitric acid that is sold has been dissolved in water. Because of its corrosive nature, nitric acid swiftly causes serious chemical burns.

 Health dangers from inhaling nitric acid mists include mucous membrane damage and possibly death. The cornea could become permanently damaged if nitric acid comes into touch with the eyes.

Name of Molecule Nitric acid
Molecular Geometry trigonal planar
Hybridization Sp2
Molecular Formula HNO3
Molecular Weight 63.01 g/mol
Bond Pairs 5
Lone Pairs 7

Valence Electrons

Valence electrons are the electrons that make up an atom’s top energy level or outermost shell.

  • The number of valence electrons in each atom is the first thing we count while calculating the formal charges.

 characteristics of valence electrons

  • For the main group elements, the valence electron only exists in the outermost electron shell.
  • A valence electron may be present in a transition metal’s inner shell.
  • If an atom has a closed shell, valence electrons are often chemically inactive.
  • For valence electron transition, energy will either be absorbed or released in the form of a photon.
  • Valence electrons also have a role in determining an element’s electrical conductivity. Element types include metal, non-metal, and metalloid depending on their nature.

Formal Charges

The charge that would be present on an atom in a molecule if all of the bonding electrons were distributed equally is known as the formal charge of the atom. It is employed to evaluate stability.

HNO3 Lewis Structure

HNO3 Nitric Acid

A Lewis structure can be used to visualize how the valence electrons are positioned around specific molecules’ atoms.

Lewis structure does not attempt to describe how bonds are formed, how electrons are shared among atoms or the geometry of molecules. The most constrained theory of electrical structure is this one.

Steps to Draw HNO3 Lewis Structure 

1. Choosing the central atom

The first step while drawing the HNO3 Lewis Structure is to arrange the trivalent nitrogen atom, which has the maximum valence, in the middle of the system. N should be surrounded by divalent oxygen.

2. Determine the Total no. of Valence Electrons

The second thing you must determine number of valence electrons:

Nitrogen has 5 electrons, Oxygen has 6 electrons and Hydrogen has 1 electron

5 + 3 x 6 + 1 = 24

3. Indicate the Total Lone Pair and Bond Pair of Electrons

Now we will count the number of electrons surrounding each atom in the HNO3 Lewis Structure:

    • The nitrogen atom contains four bonds and no lone pairs.
    • The oxygen atom has two bonding and four non-bonding electrons.
    • The hydroxyl oxygen atom has two bonds and four non-bonding electrons.
    • Six non-bonding electrons and one bond are present on the other oxygen atom.
    • The hydrogen atom contains one bond and no lone pairs

4. Connect electrons to form bonds

In the second last step of drawing the HNO3 Lewis Structure, join electrons to create the following bonds:

  • Create a bond on either side from nitrogen to oxygen.
  • Include a double bond connecting oxygen and nitrogen.
  • Create a connection between hydrogen and oxygen. This functional group, which consists of oxygen bound to hydrogen by a single link, is known as hydroxyl.

So far, we have created five bonds using 10 electrons. The remaining 14 electrons (24 – 10 = 14) will be found in 7 lone pairs.

HNO3 Lewis Structure

5. Show Atomic Charges

In the final step of drawing the HNO3 Lewis Structure, we should know that the formal charges and total charges are displayed on Lewis structures. The molecule of nitric acid is neutral. However, it has nitrogen with a formal charge of +1 and oxygen with a formal charge of -1 in its structure.

  • For nitrogen, 5 – (0 + 4) = 1
  • For the hydroxyl oxygen, 6 – (4 + 2) = 0
  • For the other oxygen, 6 – (6 + 1) = -1
  • For the hydrogen, 1 – (0 + 1) = 0
  • As expected, the formal charges add to zero for a neutral molecule: 1 + 0 + -1 + 0 = 0

 Importance of Lewis Structure in Chemistry

  • Lewis Structure’s main objective is to make it easier for scientists and students to speculate about the most stable structure that a molecule can have while establishing interactions with other molecules.
  • Using the Lewis method to depict molecular structures has many other advantages.
  • It uses straightforward graphical representations of the valence electrons present in the outermost shell of atoms to estimate the type and quantity of bonds, the formation of chemical bonds, the total formal charge, and the characteristics of molecules.

 Importance of HNO3 Lewis Structure 

  • The Lewis structure of a molecule represents its electron distribution and helps in understanding its chemical behavior.
  • Nitric acid (HNO3) is an important molecule in various industrial processes, including the production of fertilizers, explosives, and dyes.
  • The HNO3 Lewis Structure shows that it consists of one hydrogen atom, one nitrogen atom, and three oxygen atoms.
  • In the HNO3 Lewis Structure nitrogen atom is in the center of the molecule, and each of the oxygen atoms is bonded to the nitrogen atom.
  • One of the oxygen atoms is also bonded to the hydrogen atom.
  • The HNO3 Lewis Structure also shows that the molecule has a trigonal planar geometry with a bent shape.
  • The bent shape of HNO3 is due to the lone pair of electrons on the nitrogen atom, which repels the bonded electron pairs, causing the molecule to bend.
  • The HNO3 Lewis Structure helps in predicting the polarity of the molecule and its reactivity towards other molecules.

Molecular Geometry and Shape of the HNO3

HNO3 Nitric Acid

The three-dimensional configuration of atoms within a molecule is known as molecular geometry. The several atom varieties and the interaction of their electrons enable molecules to form in a specified manner, and their forms can be estimated by using molecular geometry.

 We can understand the molecular geometry of HNO3 using the Valence Shell Electron Pair Repulsion theory or VSEPR. According to the VSEPR theory, a pair of electrons or bonds should be as far apart as possible to maintain the least amount of repulsion.

As a result, the molecules give a fixed form. The HNO3 molecule has a trigonal planar form.

The Geometry of HNO3 Molecule by AXN Notion

The HNO3 molecule’s shape according to the AXN idea

The AXN approach is employed when implementing the VSEPR theory. Since

  • N shows lone pair on the center atom
  • A is the primary atom
  • X is an atom that is bound to A

HNO3’s triangular planar geometry, which is made up of branching atoms, represents a perfect plane (no lone pair of electrons). Trigonal planar is similar to an AX3 system in the system of molecular geometry.

Shape & Bond Angle and of HNO3

HNO3 Nitric Acid

A trigonal planar molecular geometry model is said to have one atom in the middle and three others at each corner of an equilateral triangle, all in the same plane, according to VSPER theory. In a perfect trigonal planar species, all three atoms have 120° bond angles and are identical to one another.

HNO3 has a trigonal planar overall shape with 120-degree bond angles.

Polarity of HNO3

Polarity of HNO3 Nitric Acid

A compound’s polarity is a measurement of the strength of the attraction between its atoms. One atom or molecule may have a greater “pull” than another due to this attraction, which can result in a variation in electronegativity and give rise to polar molecules.

HNO3 is an asymmetrical molecule, as we can see. On the opposing sides of each other, we have an atom of hydrogen and oxygen. Since HNO3 is a polar molecule, there will be two opposite poles as a result of the difference in electronegativity.

Read Also: Sulfur Difluoride (SF2): Lewis Structure, Molecular Geometry, Hybridization, Properties, and Uses

HCN Lewis Structure, Molecular Geometry, Hybridization, and Polarity

SF6 Lewis Structure, Molecular Geometry, Shapes, and Polarity

Factors Influencing Polarity

  1. Participating in Atom Relative Electronegativity

A more electronegative element will be able to draw the electrons more strongly toward itself because the bond polarity entails dragging the electrons toward itself.

The different electronegativity of the atoms that make up the molecule is one of the key elements. A highly polar molecule results from an unequal electron sharing that increases with a difference. The relative electronegativity of the involved atoms will determine the extent of shifting.

N has an E.N of 3.04, O of 3.44, and H of 2.2. There is a 2.2211D dipole moment overall.

  1. Molecular Shape

  • The polarization of a molecule is highly reliant on the form of the molecule. If the arrangement is symmetrical and the length of the arrows is equal, the molecule will be nonpolar.
  • The arrangement will be uneven if the arrows are different lengths since the molecule is polar and they will not balance one another.

Whether a molecule is polar or non-polar will depend on its general form. The arrangement is asymmetrical in the case of HNO3, which has a polar molecule and a trigonal pyramidal shape.

They have a 120-degree bond angle.

  1. Dipole Moment

Dipole moment of HNO3 Nitric Acid

Dipole moment establishes as a result of unequal sharing of electrons. Dipole moments happen if there is a separation of charge.

The difference in electronegativity will be greater if the dipole moment is larger. We can measure the dipole moment thanks to the molecule’s polarity.

HNO3 is a polar molecule because its three bonds result in four dipoles that do not cancel one another out. They combine to create a net dipole moment of around 2.22111 Debye.

Hybridization of HNO3

Hybridization of HNO3 Nitric Acid

Hybridization is the process through which atomic orbitals combine to create newly hybridized orbitals, which in turn affects molecule geometry and bonding characteristics. A valence bond theory expansion, this procedure (VBT).

HNO3 is a molecule made up of two atomic orbitals that hybridized to form its Lewis structure. As is well known, oxygen in the OH ion has a steric number of 4, whereas nitrogen has a steric number of 3.                                                     

 In HNO3, the O atom is present in SP2 hybridization and the N atom is present in SP2 hybridization.

Nitric acid, therefore, possesses 13 (3 + 4 + 2*3) hybrid orbitals prior to bonding, while only six hybrid orbitals are visible after the bonding.  

Molecular Orbital theory of HNO3

MOT of HNO3 Nitric Acid

A nitrogen atom’s 2sp2 orbital and an O atom’s hybrid orbital atom combine to generate the sigma bonds between N and O atoms. As a result, three-dimensional sigma bonding orbitals and antibonding orbitals are created.

The hydrogen and oxygen single sigma bond utilizes the hydrogen’s 1s orbital and the oxygen’s 2sp3 orbital. A sigma bonding and antibonding orbital are formed as a consequence.

Together, the atoms of nitrogen and oxygen form three pi orbitals. The 2sp2 orbitals on an oxygen atom are not involved in bonding.

Characteristics of HNO3

  • Nitric corrosive is an extraordinary acid that turns blue litmus reddish. On remaining, nitric acid corrodes and transforms into earthy-coloured nitrogen dioxide.

This serves as justification for why it eventually turns a hearty brownish colour. Nitrogen dioxide, which is earthy in colour, is formed when nitric acid corrodes. This explains why it turns caramel over time even though fresh nitric acid is colourless.          

                                  4HNO3 → 4NO2 + O2 + 2H2O

  • With metals above hydrogen in the metal action series, nitric acid is corrosive and releases hydrogen gas.

                               Mg + 2HNO3 → Mg(NO3)2 + H2

                               Mn + 2HNO3 → Mn(NO3)2 + H2

Uses of Nitric Acid

  • It carries ammonium nitrates, which are used to make plastic, variety, and manures (fertilizers).
  • It’s utilized as a material doping expert in electrochemistry; it’s used in the production of explosives like TNT; it’s used as an oxidizer in liquid-fueled rockets.


The Lewis structure of HNO3 and its significance in chemistry are the topics of the essay. Science places a great deal of attention on HNO3; its Lewis structure, subatomic calculations, and hybridization help us learn a great deal about this important compound.

We have concentrated on the Lewis structure of HNO3, its molecular geometry, hybridization, and its formal charge in this paper. Understanding these facts will help us better understand the form and characteristics of this chemical.


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