Is KrF2 Polar or Nonpolar? (And Why?)

KrF2 is a NONPOLAR molecule.

But why? 

And how can you say that KrF2 is a nonpolar molecule?

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

KrF2 is a NONPOLAR molecule because both the bonds (Kr-F bonds) are identical and KrF2 has symmetrical geometry which cancels out the bond polarity.

Let me explain this in detail with the help of KrF2 lewis structure and its 3D geometry.

Why is KrF2 a Nonpolar molecule? (Explained in 3 Steps)

KrF2 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 3 steps!

Step #1: Draw the lewis structure

Here is a skeleton of KrF2 lewis structure and it contains two Kr-F bonds.

(Note: If you want to know the steps of drawing the KrF2 lewis dot structure, then visit this article: KrF2 lewis structure, Or you can also watch this short 2 minute video).

So from the above diagram we have come to know that the KrF2 molecule has two Kr-F bonds.

Now in the next step we have to check whether these two Kr-F bonds are polar or nonpolar.

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 KrF2 molecule. It has two Kr-F bonds.

You can see the electronegativity values of Krypton (Kr) and Fluorine (F) atoms from the periodic table given below.

From the above image;

• Electronegativity of Krypton (Kr) = 3 ^[6]
• Electronegativity of Fluorine (F) = 3.98 ^[7]

Now let’s see the polarity of each bond.

For Kr-F bond;
The electronegativity difference (ΔEN) = 3.98 – 3 = 0.98
This value lies between 0.4 to 1.7, which indicates that the bond between Krypton (Kr) and Fluorine (F) is polar.
Hence, each Kr-F bond is a polar covalent bond.

You can see in the above image that because of electronegativity difference, the partial positive charge (ẟ+) appears on the Krypton atom (Kr) and partial negative charge (ẟ-) appears on the Fluorine atoms (F).

But wait, this alone won’t tell you whether the entire KrF2 molecule is polar or nonpolar.

So let’s proceed to the next step to check the symmetry of the KrF2 molecule.

Step #3: Check whether the molecule is symmetric or not

Have a look at this 3D structure of KrF2. You can see that the structure of KrF2 is symmetrical. 

The krypton atom is at the center and it is surrounded by 2 fluorine atoms which are equidistant as well as at equal angles.

Also the three lone pairs are arranged symmetrically.

As both the bonds (Kr-F) are symmetrical and the KrF2 molecule has a symmetrical geometry, their bond polarity gets canceled with each other.

Because of this, there are no positive and negative poles of charges on the overall molecule of KrF2.

Hence, the KrF2 molecule is a nonpolar molecule.

I hope you have understood the reason behind the nonpolar nature of KrF2 molecule.

See the polarity of other molecules to make your concepts clear:
Is BrCl5 Polar or Nonpolar?
Is ClO2- Polar or Nonpolar?
Is XeCl4 Polar or Nonpolar?
Is NOBr Polar or Nonpolar?
Is GeH4 Polar or Nonpolar?