Is N2H4 Polar or Nonpolar? (And Why?)

N2H4 is a POLAR molecule.

But why? 

And how can you say that N2H4 is a polar molecule?

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

N2H4 is a POLAR molecule because the Nitrogen (N) present in the molecule is more electronegative and both the Nitrogen 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 N2H4 molecule polar.

Let me explain this in detail with the help of N2H4 lewis structure and its 3D geometry.

Why is N2H4 a Polar molecule? (Explained in 3 Steps)

N2H4 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 N2H4 lewis structure and it contains four N-H bonds and one N-N bond.

(Note: If you want to know the steps of drawing the N2H4 lewis dot structure, then visit this article: N2H4 lewis structure, Or you can also watch this short 2 minute video).

So from the above diagram we have come to know that the N2H4 molecule has four N-H bonds and one N-N 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 N2H4.

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] [5]}

Now let’s come to the example of N2H4 molecule. It has four N-H bonds and one N-N bond.

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, each N-H bond is a polar covalent bond.

For Nitrogen-Nitrogen bond;
The electronegativity difference (ΔEN) = 3.04 – 3.04 = 0 
This value is less than 0.4, which indicates that the N-N is nonpolar.
Hence, the N-N bond is a nonpolar covalent bond.

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

But wait, we also have to look at the molecular geometry of N2H4 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 N2H4. The two Nitrogen atoms (N) are at the center and it is surrounded by Hydrogen atoms (H).

It also has one lone pair on each Nitrogen atom (N).

Due to the lone pair on the nitrogen atoms (N), its molecular geometry becomes asymmetric.

Because of this, there are positive and negative poles of charges on the overall molecule of N2H4.

Hence, the N2H4 molecule is a polar molecule.

I hope you have understood the reason behind the polar nature of N2H4 molecule.

See the polarity of other molecules to make your concepts clear:
Is SeCl2 Polar or Nonpolar?
Is BeI2 Polar or Nonpolar?
Is TeF4 Polar or Nonpolar?
Is AlBr3 Polar or Nonpolar?
Is KrF4 Polar or Nonpolar?