Is C2H2 Polar or Nonpolar? (And Why?)

C2H2 is a NONPOLAR molecule.

But why? 

And how can you say that C2H2 is a nonpolar molecule?

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

C2H2 is a NONPOLAR molecule because all the individual bonds are nonpolar and C2H2 has symmetrical geometry.
In other words, the electronegativity difference of these bonds is very less. Hence the C2H2 molecule is a nonpolar molecule.

Let me explain this in detail with the help of C2H2 lewis structure and its 3D geometry.

Why is C2H2 a Nonpolar molecule? (Explained in 2 Steps)

C2H2 is a nonpolar molecule because it does not have any pole of positive charge and negative charge on it.

Let me explain this to you in just 2 steps!

Step #1: Draw the lewis structure

Here is a skeleton of C2H2 lewis structure and it contains one Carbon-Carbon bond and two C-H bonds.

(Note: If you want to know the steps of drawing the C2H2 lewis dot structure, then visit this short 2 minute video).

So from the above diagram we have come to know that the C2H2 molecule has one Carbon-Carbon bond and two C-H 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 C2H2.

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 C2H2 molecule. It has Carbon-Carbon bond as well as C-H bonds.

You can see the electronegativity values of Carbon (C) and Hydrogen (H) 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]

Now let’s see the polarity of each bond.

For Carbon-Carbon bond;
The electronegativity difference (ΔEN) = 2.55 – 2.55 = 0 
This value is less than 0.4, which indicates that the Carbon-Carbon is nonpolar.
Hence, the Carbon-Carbon bond is a nonpolar covalent 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.

As Carbon-Carbon bond and C-H bonds are nonpolar, there will not be any partial positive charge (ẟ+) or partial negative charge (ẟ-) on the carbon and hydrogen atoms.

From this, you can easily get the idea that the C2H2 molecule is a nonpolar molecule.

But let’s also see whether this C2H2 molecule has a symmetric geometry or not.

Have a look at this 3D structure of C2H2. You can see that the structure of C2H2 is symmetrical. 

The two carbon atoms are at the center and they are surrounded by hydrogen atoms which are equidistant as well as at equal angles.

As all the bonds are nonpolar and the C2H2 molecule has a symmetrical geometry, there are no positive and negative poles of charges on the overall molecule of C2H2.

Hence, the C2H2 molecule is a nonpolar molecule.

I hope you have understood the reason behind the nonpolar nature of C2H2 molecule.

See the polarity of other molecules to make your concepts clear:
Is NCl3 Polar or Nonpolar?
Is SF2 Polar or Nonpolar?
Is C2H4 Polar or Nonpolar?
Is XeF2 Polar or Nonpolar?
Is ClF3 Polar or Nonpolar?