Is O3 Polar or Nonpolar? (And Why?)

O3 is a POLAR molecule.

But why? 

And how can you say that O3 is a polar molecule?

Want to know the reason?
Let’s dive into it!

O3 is a POLAR molecule because it has one lone pair of electrons on the central Oxygen atom (O) which causes the entire molecule to bend.
This bending of O3 molecule results in asymmetric geometry, which makes the molecule polar.

Let me explain this in detail with the help of O3 lewis structure and its 3D geometry.

Why is O3 a Polar molecule? (Explained in 2 Steps)

To understand the polar nature of O3 molecule, first of all you should know its lewis structure as well as its molecular geometry.

So let’s see this in the steps below.

Step #1: Draw the lewis structure

Here is a skeleton of O3 lewis structure and it contains one O-O bond and one O=O bond (in short it has two Oxygen-Oxygen bonds).

(Note: If you want to know the steps of drawing the O3 lewis dot structure, then visit this article: O3 lewis structure, Or you can also watch this short 2 minute video).

So from the above diagram we have come to know that the O3 molecule has two Oxygen-Oxygen bonds.

Now in the next step we have to check whether these bonds are polar or nonpolar.

And we also have to check the molecular geometry of O3.

Step #2: Check the bond polarity and molecular geometry

The chemical bonds can be either nonpolar, polar or ionic depending on the difference of the electronegativity values (ΔEN) between the two atoms.

Have a look at the above image.

• If the electronegativity difference (ΔEN) is less than 0.4, then the bond is nonpolar covalent bond.
• If the electronegativity difference (ΔEN) is between 0.4 to 1.7, then the bond is polar covalent bond. 
• If the electronegativity difference (ΔEN) is greater than 1.7, then the bond is an ionic bond. ^{[1] [2] [3] [4]}

Now let’s come to the example of O3 molecule. It has Oxygen-Oxygen bonds.

You can see the electronegativity values of Oxygen (O) atoms from the periodic table given below.

From the above image;

• Electronegativity of Oxygen (O) = 3.44 ^[5]

So for Oxygen-Oxygen bonds, the electronegativity difference (ΔEN) = 3.04 – 3.04 = 0

This value is less than 0.4, which indicates that the bond between both the Oxygen (O) atoms is nonpolar covalent bond.

But let’s keep this discussion aside.

Because we also have to look at the molecular geometry of O3 to know whether it has a symmetric shape or not.

Have a look at this 3D structure of O3. 

The central Oxygen atom (O) has one lone pair of electrons.

Due to the lone pair on the central oxygen atom (O), its molecular geometry becomes asymmetric.

Because of this, there are positive and negative poles of charges on the overall molecule of O3.

Hence, the O3 molecule is a polar molecule.

I hope you have understood the reason behind the polar nature of O3 molecule.

See the polarity of other molecules to make your concepts clear:
Is NO3- Polar or Nonpolar?
Is CH2F2 Polar or Nonpolar?
Is SiCl4 Polar or Nonpolar?
Is F2 Polar or Nonpolar?
Is I2 Polar or Nonpolar?