Is IF3 Polar or Nonpolar? (And Why?)

IF3 is a POLAR molecule.

But why? 

And how can you say that IF3 is a polar molecule?

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

IF3 is a POLAR molecule because the Fluorine (F) present in the molecule is more electronegative, which causes the partial positive (ẟ+) and partial negative (ẟ-) charge to appear on the molecule. These ẟ+ and ẟ- charges are responsible to make the entire IF3 molecule polar.

Let me explain this in detail with the help of IF3 lewis structure and its 3D geometry.

Why is IF3 a Polar molecule? (Explained in 3 Steps)

IF3 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 IF3 lewis structure and it contains three I-F bonds.

(Note: If you want to know the steps of drawing the IF3 lewis dot structure, then visit this article: IF3 lewis structure, Or you can also watch this short 2 minute video).

So from the above diagram we have come to know that the IF3 molecule has three I-F bonds.

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

And we also have to check the molecular geometry of IF3.

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 IF3 molecule. It has three I-F bonds.

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

From the above image;

• Electronegativity of Iodine (I) = 2.66 ^[6]
• Electronegativity of Fluorine (F) = 3.98 ^[7]

Now let’s see the polarity of each bond.

For I-F bond;
The electronegativity difference (ΔEN) = 3.98 – 2.66 = 1.32
This value lies between 0.4 to 1.7, which indicates that the bond between Iodine (I) and Fluorine (F) is polar.
Hence, the I-F bond is a polar covalent bond.

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

But wait, we also have to look at the molecular geometry of IF3 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 IF3. The Iodine atom (I) is at the center and it is surrounded by 3 Fluorine atoms (F).

It also has two lone pairs on the Iodine atom (I).

Due to the lone pairs on the iodine atom (I), its molecular geometry becomes asymmetric.

Because of this, there are positive and negative poles of charges on the overall molecule of IF3.

Hence, the IF3 molecule is a polar molecule.

I hope you have understood the reason behind the polar nature of IF3 molecule.

See the polarity of other molecules to make your concepts clear:
Is ClF5 Polar or Nonpolar?
Is SCN- Polar or Nonpolar?
Is ICl5 Polar or Nonpolar?
Is CO3 2- Polar or Nonpolar?
Is COF2 Polar or Nonpolar?