ICl3 Lewis structure

ICl₃ (iodine trichloride) has one iodine atom and three chlorine atoms.

In the ICl₃ Lewis structure, 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.

Alternative method: Lewis structure of ICl₃

Rough sketch

• First, determine the total number of valence electrons

In the periodic table, both iodine and chlorine lie in group 17.

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

Learn how to find: Chlorine valence electrons

• 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

Lone pair

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.

Also remember that iodine is a period 5 element, so it can keep more than 8 electrons in its last shell. And chlorine is a period 3 element, so it can keep more than 8 electrons in its last shell.

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:

Formal charge

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.

Final structure

The final structure of ICl₃ includes a central iodine atom connected to three chlorine atoms through single covalent bonds. Within this layout, the iodine atom serves as an exception to the octet rule, employing an expanded valence shell to accommodate ten electrons through three bonding pairs and two lone pairs. Each chlorine atom satisfies its octet by retaining three lone pairs alongside its single shared bond with the central iodine. This configuration is the most stable because it results in formal charges of zero for every atom, representing the most energetically favorable state for the molecule. Therefore, this specific electronic distribution serves as the definitive and most accurate Lewis representation of iodine trichloride.

Next: NOF Lewis structure

External video

• A step-by-step explanation of how to draw the ICl3 Lewis Structure – YouTube • Wayne Breslyn

External links

• https://techiescientist.com/icl3-lewis-structure/
• https://lambdageeks.com/icl3-lewis-structure/
• https://www.thegeoexchange.org/chemistry/bonding/Lewis-Structures/ICl3-lewis-structure.html
• https://sciedutut.com/icl3-lewis-structure/