Is KrF4 Polar or Nonpolar? (And Why?)

KrF4 is a NONPOLAR molecule.

But why? 

And how can you say that KrF4 is a nonpolar molecule?

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

KrF4 is a NONPOLAR molecule because all the four bonds (Kr-F bonds) are identical and KrF4 has symmetrical geometry which cancels out the bond polarity.

Let me explain this in detail with the help of KrF4 lewis structure and its 3D geometry.

Why is KrF4 a Nonpolar molecule? (Explained in 3 Steps)

KrF4 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 KrF4 lewis structure and it contains four Kr-F bonds.

(Note: If you want to know the steps of drawing the KrF4 lewis dot structure, then visit this article: KrF4 lewis structure, Or you can also watch this short 2 minute video).

So from the above diagram we have come to know that the KrF4 molecule has four Kr-F bonds.

Now in the next step we have to check whether these four 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]}

Now let’s come to the example of KrF4 molecule. It has four 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 ^[5]
• Electronegativity of Fluorine (F) = 3.98 ^[6]

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 KrF4 molecule is polar or nonpolar.

So let’s proceed to the next step to check the symmetry of the KrF4 molecule.

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

Have a look at this 3D structure of KrF4. You can see that the structure of KrF4 is symmetrical. 

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

As all the four bonds (Kr-F) are symmetrical and the KrF4 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 KrF4.

Hence, the KrF4 molecule is a nonpolar molecule.

I hope you have understood the reason behind the nonpolar nature of KrF4 molecule.

See the polarity of other molecules to make your concepts clear:
Is NBr3 Polar or Nonpolar?
Is SO2Cl2 Polar or Nonpolar?
Is SbF3 Polar or Nonpolar?
Is SeF2 Polar or Nonpolar?
Is C2Cl4 Polar or Nonpolar?