Is BeH2 Polar or Nonpolar? (And Why?)

BeH2 is a NONPOLAR molecule.

But why? 

And how can you say that BeH2 is a nonpolar molecule?

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

BeH2 is a NONPOLAR molecule because both the bonds (Be-H bonds) are identical and BeH2 has symmetrical geometry which cancels out the bond polarity.

Let me explain this in detail with the help of BeH2 lewis structure and its 3D geometry.

Why is BeH2 a Nonpolar molecule? (Explained in 3 Steps)

BeH2 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 BeH2 lewis structure and it contains two Be-H bonds.

(Note: If you want to know the steps of drawing the BeH2 lewis dot structure, then visit this article: BeH2 lewis structure, Or you can also watch this short 2 minute video).

So from the above diagram we have come to know that the BeH2 molecule has two Be-H bonds.

Now in the next step we have to check whether these two Be-H 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 BeH2 molecule. It has two Be-H bonds.

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

From the above image;

• Electronegativity of Beryllium (Be) = 1.57 ^[6]
• Electronegativity of Hydrogen (H) = 2.2 ^[7]

Now let’s see the polarity of each bond.

For Beryllium-Hydrogen bond;
The electronegativity difference (ΔEN) = 2.2 – 1.57 = 0.63
This value lies between 0.4 to 1.7, which indicates that the bond between Beryllium (Be) and Hydrogen (H) is polar.
Hence, each Beryllium-Hydrogen 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 Hydrogen atoms (H).

But wait, this alone won’t tell you whether the entire BeH2 molecule is polar or nonpolar.

So let’s proceed to the next step to check the symmetry of the BeH2 molecule.

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

Have a look at this 3D structure of BeH2. You can see that the structure of BeH2 is symmetrical. 

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

As both the bonds (Be-H) are symmetrical and the BeH2 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 BeH2.

Hence, the BeH2 molecule is a nonpolar molecule.

I hope you have understood the reason behind the nonpolar nature of BeH2 molecule.

See the polarity of other molecules to make your concepts clear:
Is Cyclohexane (C6H12) Polar or Nonpolar?
Is IOF5 Polar or Nonpolar?
Is NH2Cl Polar or Nonpolar?
Is HNO3 Polar or Nonpolar?
Is IBr3 Polar or Nonpolar?