ICl3 (iodine trichloride) has one iodine atom and three chlorine atoms. In the lewis structure of ICl3, there are three single bonds around the iodine atom, with three chlorine atoms attached to it. Each chlorine atom has three lone pairs, and the iodine atom has two lone pairs.
Here’s how you can draw the ICl3 lewis structure step by step.
Step #1: draw sketch
Step #2: mark lone pairs
Step #3: mark charges (if there are)
Let’s break down each step in detail.
#1 Draw Sketch
- First, determine the total number of valence electrons
Hence, both iodine and chlorine have seven valence electrons.
Since ICl3 has one iodine atom and three chlorine atoms, so…
Valence electrons of one iodine atom = 7 × 1 = 7
Valence electrons of three chlorine atoms = 7 × 3 = 21
And the total valence electrons = 7 + 21 = 28
- Second, find the total electron pairs
We have a total of 28 valence electrons. And when we divide this value by two, we get the value of total electron pairs.
Total electron pairs = total valence electrons ÷ 2
So the total electron pairs = 28 ÷ 2 = 14
- Third, determine the central atom
We have to place the least electronegative atom at the center.
Since iodine is less electronegative than chlorine, assume that the central atom is iodine.
Therefore, place iodine in the center and chlorines on either side.
- And finally, draw the rough sketch
#2 Mark Lone Pairs
Here, we have a total of 14 electron pairs. And three I — Cl bonds are already marked. So we have to only mark the remaining eleven electron pairs as lone pairs on the sketch.
Always start to mark the lone pairs from outside atoms. Here, the outside atoms are chlorines.
So for each chlorine, there are three lone pairs, and for iodine, there are two lone pairs.
Mark the lone pairs on the sketch as follows:
#3 Mark Charges
Use the following formula to calculate the formal charges on atoms:
Formal charge = valence electrons – nonbonding electrons – ½ bonding electrons
For iodine atom, formal charge = 7 – 4 – ½ (6) = 0
For each chlorine atom, formal charge = 7 – 6 – ½ (2) = 0
Here, both iodine and chlorine atoms do not have charges, so no need to mark the charges.
And in the above structure, you can see that the central atom (iodine) forms an octet. Hence, the octet rule is satisfied.
Therefore, this structure is the stable lewis structure of ICl3.
Next: NOF Lewis Structure