Is IOF5 Polar or Nonpolar? (And Why?)

IOF5 is a POLAR molecule.

But why? 

And how can you say that IOF5 is a polar molecule?

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

IOF5 is a POLAR molecule because the I-F bonds and I=O bond present in the molecule are polar and it has asymmetric geometry 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 IOF5 molecule polar.

Let me explain this in detail with the help of IOF5 lewis structure and its 3D geometry.

Why is IOF5 a Polar molecule? (Explained in 3 Steps)

IOF5 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 IOF5 lewis structure and it contains five I-F bonds and one I=O bond.

So from the above diagram we have come to know that the IOF5 molecule has five I-F bonds and one I=O bond.

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

And we also have to check the molecular geometry of IOF5.

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 IOF5 molecule. It has five I-F bonds and one I=O bond.

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

From the above image;

• Electronegativity of Iodine (I) = 2.66 ^[6]
• Electronegativity of Oxygen (O) = 3.44 ^[7]
• Electronegativity of Fluorine (F) = 3.98 ^[8]

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, each I-F bond is a polar covalent bond.

For I=O bond;
The electronegativity difference (ΔEN) = 3.44 – 2.66 = 0.78 
This value lies between 0.4 to 1.7, which indicates that the bond between Iodine (I) and Oxygen (O) is polar.
Hence, the I=O bond is a polar covalent bond.

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

(Note: There is more negative charge on fluorine atoms as compared to oxygen atom, because fluorine is more electronegative than oxygen.)

But wait, we also have to look at the molecular geometry of IOF5 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 IOF5. The Iodine atom (I) is at the center and it is surrounded by 5 Fluorine atoms (F) and 1 Oxygen atom (O).

It has asymmetric geometry because of different bond lengths and difference in electronegativity of I-F bonds and I=O bond.

Because of this, there are positive and negative poles of charges on the overall molecule of IOF5.

Hence, the IOF5 molecule is a polar molecule.

I hope you have understood the reason behind the polar nature of IOF5 molecule.

See the polarity of other molecules to make your concepts clear:
Is NH2Cl Polar or Nonpolar?
Is HNO3 Polar or Nonpolar?
Is IBr3 Polar or Nonpolar?
Is NH2- Polar or Nonpolar?
Is KrF2 Polar or Nonpolar?