Is CHBr3 Polar or Nonpolar? (And Why?)

CHBr3 is a POLAR molecule.

But why? 

And how can you say that CHBr3 is a polar molecule?

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

CHBr3 is a POLAR molecule because the C-Br bonds present in the molecule are polar, which causes the partial positive (ẟ+) and partial negative (ẟ-) charge to appear on the molecule. These ẟ+ and ẟ- charges are responsible to make the entire CHBr3 molecule polar.

Let me explain this in detail with the help of CHBr3 lewis structure and its 3D geometry.

Why is CHBr3 a Polar molecule? (Explained in 2 Steps)

CHBr3 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 2 steps!

Step #1: Draw the lewis structure

Here is a skeleton of CHBr3 lewis structure and it contains one C-H bond and three C-Br bond.

(Note: If you want to know the steps of drawing the CHBr3 lewis dot structure, then visit this article: CHBr3 lewis structure, Or you can also watch this short 2 minute video).

So from the above diagram we have come to know that the CHBr3 molecule has one C-H bond and three C-Br bonds.

Now in the next step we have to check whether the C-H bond and C-Br bonds are polar or nonpolar.

And we also have to check the molecular geometry of CHBr3.

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] [5]}

Now let’s come to the example of CHBr3 molecule. It has one C-H bond and three C-Br bonds.

You can see the electronegativity values of Carbon (C), Hydrogen (H) and Bromine (Br) atoms from the periodic table given below.

From the above image;

• Electronegativity of Carbon (C) = 2.55 ^[6]
• Electronegativity of Hydrogen (H) = 2.2 ^[7]
• Electronegativity of Bromine (Br) = 2.96 ^[8]

Now let’s see the polarity of each bond.

For C-H bond;
The electronegativity difference (ΔEN) = 2.55 – 2.2 = 0.35 
This value is less than 0.4, which indicates that the bond between Carbon (C) and Hydrogen (H) is nonpolar.
Hence, each C-H bond is a nonpolar covalent bond.

For C-Br bond;
The electronegativity difference (ΔEN) = 2.96 – 2.55 = 0.41
This value lies between 0.4 to 1.7, which indicates that the bond between Carbon (C) and Bromine (Br) is polar.
Hence, the C-Br bond is a polar covalent bond.

You can see in the above image that because of large electronegativity difference of Carbon and Bromine atom, the partial positive charge (ẟ+) appears on the Carbon atom (C) and partial negative charge (ẟ-) appears on the Bromine atoms (Br).

From this, you can easily get the idea that the CHBr3 molecule is a polar molecule.

But let’s also see its 3D molecular geometry for better understanding.

Have a look at this 3D structure of CHBr3. The more electronegative bromine atom (Br) has a tendency to pull the shared electron pair towards itself, which results in partial positive charge on carbon atom (C) and partial negative charge on bromine atoms (Br).

Because of this, there are positive and negative poles of charges on the overall molecule of CHBr3.

Hence, the CHBr3 molecule is a polar molecule.

I hope you have understood the reason behind the polar nature of CHBr3 molecule.

See the polarity of other molecules to make your concepts clear:
Is ICl4- Polar or Nonpolar?
Is XeCl2 Polar or Nonpolar?
Is AsF3 Polar or Nonpolar?
Is SCl4 Polar or Nonpolar?
Is NI3 Polar or Nonpolar?