Is BeI2 Polar or Nonpolar? (And Why?)

BeI2 is a NONPOLAR molecule.

But why? 

And how can you say that BeI2 is a nonpolar molecule?

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

BeI2 is a NONPOLAR molecule because both the bonds (Be-I bonds) are identical and BeI2 has symmetrical geometry which cancels out the bond polarity.

Let me explain this in detail with the help of BeI2 lewis structure and its 3D geometry.

Why is BeI2 a Nonpolar molecule? (Explained in 3 Steps)

BeI2 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 BeI2 lewis structure and it contains two Be-I bonds.

(Note: If you want to know the steps of drawing the BeI2 lewis dot structure, then visit this article: BeI2 lewis structure, Or you can also watch this short 2 minute video).

So from the above diagram we have come to know that the BeI2 molecule has two Be-I bonds.

Now in the next step we have to check whether these two Be-I 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 BeI2 molecule. It has two Be-I bonds.

You can see the electronegativity values of Beryllium (Be) and Iodine (I) atoms from the periodic table given below.

From the above image;

• Electronegativity of Beryllium (Be) = 1.57 ^[6]
• Electronegativity of Iodine (I) = 2.66 ^[7]

Now let’s see the polarity of each bond.

For Be-I bond;
The electronegativity difference (ΔEN) = 2.66 – 1.57 = 1.09
This value lies between 0.4 to 1.7, which indicates that the bond between Beryllium (Be) and Iodine (I) is polar.
Hence, each Be-I 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 Beryllium atom (Be) and partial negative charge (ẟ-) appears on the Iodine atoms (I).

But wait, this alone won’t tell you whether the entire BeI2 molecule is polar or nonpolar.

So let’s proceed to the next step to check the symmetry of the BeI2 molecule.

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

Have a look at this 3D structure of BeI2. You can see that the structure of BeI2 is symmetrical. 

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

As both the bonds (Be-I) are symmetrical and the BeI2 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 BeI2.

Hence, the BeI2 molecule is a nonpolar molecule.

I hope you have understood the reason behind the nonpolar nature of BeI2 molecule.

See the polarity of other molecules to make your concepts clear:
Is TeF4 Polar or Nonpolar?
Is AlBr3 Polar or Nonpolar?
Is KrF4 Polar or Nonpolar?
Is NBr3 Polar or Nonpolar?
Is SO2Cl2 Polar or Nonpolar?