Is Ammonium ion (NH4+) Polar or Nonpolar? (And Why?)

Ammonium ion (NH4+) is a NONPOLAR ion.

But why? 

And how can you say that NH4+ is a nonpolar ion?

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

Ammonium ion (or NH4+ ion) is a NONPOLAR ion because all the four bonds (N-H bonds) are identical and NH4+ has symmetrical geometry.

Let me explain this in detail with the help of NH4+ lewis structure and its 3D geometry.

Why is NH4+ a Nonpolar ion? (Explained in 2 Steps)

NH4+ is a nonpolar ion 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 NH4+ lewis structure and it contains four N-H bonds.

(Note: If you want to know the steps of drawing the NH4+ lewis dot structure, then visit this article: NH4+ lewis structure, Or you can also watch this short 2 minute video).

So from the above diagram we have come to know that the NH4+ ion has four N-H bonds.

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

And we also have to check the molecular geometry of NH4+ ion.

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 NH4+ ion. It has four N-H bonds.

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

From the above image;

• Electronegativity of Nitrogen (N) = 3.04 ^[6]
• Electronegativity of Hydrogen (H) = 2.2 ^[7]

Now let’s see the polarity of each bond.

For N-H bond;
The electronegativity difference (ΔEN) = 3.04 – 2.2 = 0.84
This value lies between 0.4 to 1.7, which indicates that the bond between Nitrogen (N) and Hydrogen (H) is polar.
Hence, the N-H bond is a polar covalent bond.

But let’s keep this discussion aside.

Because we also have to look at the molecular geometry of NH4+ ion to know whether it has a symmetric shape or not.

Have a look at this 3D structure of NH4+ ion. You can see that the structure of NH4+ is symmetrical. 

The nitrogen atom is at the center and it is surrounded by 4 hydrogen atoms which are equidistant as well as at equal angles.

As the NH4+ ion has a symmetrical geometry, there are no positive and negative poles of charges on the overall NH4+ ion.

Hence, the NH4+ ion is a nonpolar ion.

I hope you have understood the reason behind the nonpolar nature of NH4+ ion.

See the polarity of other molecules to make your concepts clear:
Is CH3NH2 Polar or Nonpolar?
Is SO3 2- Polar or Nonpolar?
Is AsF5 Polar or Nonpolar?
Is ClF Polar or Nonpolar?
Is CH3OCH3 Polar or Nonpolar?