Is CO Polar or Nonpolar? (Why? & How?)

Is CO Polar or Nonpolar

CO (Carbon monoxide) is a POLAR molecule.

But why? 

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

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

CO (Carbon monoxide) is a POLAR molecule because any two bonding atoms whose electronegativity difference is between 0.4 to 2.0 forms a polar bond.
Here in CO molecule, the electronegativity difference of Carbon atom (C = 2.55) and Oxygen atom (O = 3.44) is 0.89 (i.e 3.44 – 2.55 = 0.89). This value (0.89) is between 0.4 and 2.0, hence the CO molecule is a polar molecule.

Didn’t understand what is written above?

Let me explain this in a short and simple way (with 3D images).

Why is CO a Polar molecule? (Explained!)

CO is a polar molecule because it has a partial positive charge (ẟ+) on the Carbon atom and partial negative charge (ẟ-) on the Oxygen atom.

In short, the CO molecule forms a pole of positive charge and negative charge on it. Hence CO is a polar molecule.

Is CO Polar or Nonpolar

But wait, let me give you some detailed information about the polarity of CO molecule.

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 CO molecule.

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

From the above image;

  • Electronegativity of Carbon (C) = 2.55 [6]
  • Electronegativity of Oxygen (O) = 3.44 [7]

So for CO, the electronegativity difference (ΔEN) = 3.44 – 2.55 = 0.89

This value lies between 0.4 to 1.7, which indicates that the bond between Carbon (C) and Oxygen (O) is polar covalent bond.

Hence, CO is a polar molecule.

How CO becomes a Polar molecule?

In a CO molecule, there is one carbon atom (C) and one oxygen atom (O). Both these atoms are covalently bonded with each other by sharing three electron pairs between them.

Is CO Polar or Nonpolar

If we compare the electronegativity of carbon and oxygen, then oxygen is more electronegative than carbon.

This means that the oxygen atom has more tendency to attract the shared electron pair towards itself.

Is CO Polar or Nonpolar

As the electron pair remains attracted towards the oxygen atom, the partial negative charge (ẟ-) appears on the Oxygen atom (O) and partial positive charge (ẟ+) appears on the Carbon atom (C).

Is CO Polar or Nonpolar

In this way the partial positive and partial negative charges are generated on the CO molecule and hence CO becomes a polar molecule.

I hope you have understood the reason behind the polarity of Carbon monoxide (i.e CO) molecule.

See the polarity of other molecules to make your concepts clear:
Is CH3F Polar or Nonpolar?
Is NOCl Polar or Nonpolar?
Is BrF5 Polar or Nonpolar?
Is C2H2 Polar or Nonpolar?
Is NCl3 Polar or Nonpolar? 


Jay is an educator and has helped more than 100,000 students in their studies by providing simple and easy explanations on different science-related topics. With a desire to make learning accessible for everyone, he founded Knords Learning, an online learning platform that provides students with easily understandable explanations.

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