Is H2O2 Polar or Nonpolar? (And Why?)

H2O2 is a POLAR molecule.

But why? 

And how can you say that H2O2 is a polar molecule?

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

H2O2 is a POLAR molecule because the Oxygen (O) present in the molecule is more electronegative and both the Oxygen atoms have lone pairs, which results in an asymmetric shape of the molecule.
Because of this, the partial positive (ẟ+) and partial negative (ẟ-) charge appears on the molecule. These ẟ+ and ẟ- charges are responsible to make the entire H2O2 molecule polar.

Let me explain this in detail with the help of H2O2 lewis structure and its 3D geometry.

Why is H2O2 a Polar molecule? (Explained in 3 Steps)

H2O2 is a polar molecule because it has poles of partial positive charge (ẟ+) and partial negative charge (ẟ-) on it.

Let me explain this to you in 3 steps!

Step #1: Draw the lewis structure

Here is a skeleton of H2O2 lewis structure and it contains two O-H bonds and one O-O bond.

(Note: If you want to know the steps of drawing the H2O2 lewis dot structure, then visit this article: H2O2 lewis structure, Or you can also watch this short 2 minute video).

So from the above diagram we have come to know that the H2O2 molecule has two O-H bonds and one O-O bond.

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 H2O2.

Step #2: Check whether individual bonds are polar or nonpolar

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 H2O2 molecule. It has two O-H bonds and one O-O bond.

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

From the above image;

• Electronegativity of Oxygen (O) = 3.44 ^[5]
• Electronegativity of Hydrogen (H) = 2.2 ^[6]

Now let’s see the polarity of each bond.

For O-H bond;
The electronegativity difference (ΔEN) = 3.44 – 2.2 = 1.24
This value lies between 0.4 to 1.7, which indicates that the bond between Oxygen (O) and Hydrogen (H) is polar.
Hence, the O-H bond is a polar covalent bond.

For Oxygen-Oxygen bond;
The electronegativity difference (ΔEN) = 3.44 – 3.44 = 0 
This value is less than 0.4, which indicates that the O-O is nonpolar.
Hence, the O-O bond is a nonpolar covalent bond.

You can see in the above image that because of higher electronegativity of Oxygen atom, the partial positive charge (ẟ+) appears on the Hydrogen atoms (H) and partial negative charge (ẟ-) appears on the Oxygen atoms (O).

But wait, we also have to look at the molecular geometry of H2O2 to know whether it has a symmetric shape or not.

Step #3: Check whether the molecule is symmetric or not

Have a look at this 3D structure of H2O2. The two Oxygen atoms (O) are at the center and it is surrounded by Hydrogen atoms (H).

It also has two lone pairs on each Oxygen atom (O).

Due to the lone pairs on the oxygen atoms (O), its molecular geometry becomes asymmetric.

Because of this, there are positive and negative poles of charges on the overall molecule of H2O2.

Hence, the H2O2 molecule is a polar molecule.

I hope you have understood the reason behind the polar nature of H2O2 molecule.

See the polarity of other molecules to make your concepts clear:
Is Ethyl acetate (C4H8O2) Polar or Nonpolar?
Is CH3Br Polar or Nonpolar?
Is PBr3 Polar or Nonpolar?
Is CF2Cl2 Polar or Nonpolar?
Is C2H6 Polar or Nonpolar?