BrCl3 Lewis structure

BrCl₃ (bromine trichloride) has one bromine atom and three chlorine atoms.

In the BrCl₃ Lewis structure, there are three single bonds around the bromine atom, with three chlorine atoms attached to it. Each chlorine atom has three lone pairs, and the bromine atom has two lone pairs.

Alternative method: Lewis structure of BrCl₃

Rough sketch

• First, determine the total number of valence electrons

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

Hence, both bromine and chlorine have seven valence electrons.

Since BrCl₃ has one bromine atom and three chlorine atoms, so…

Valence electrons of one bromine 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: Bromine valence electrons and 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 bromine is less electronegative than chlorine, assume that the central atom is bromine.

Therefore, place bromine 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 Br — 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 bromine is a period 4 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 bromine, 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 bromine atom, formal charge = 7 – 4 – ½ (6) = 0

For each chlorine atom, formal charge = 7 – 6 – ½ (2) = 0

Here, both bromine and chlorine atoms do not have charges, so no need to mark the charges.

Final structure

The final structure of BrCl₃ involves a central bromine atom connected to three chlorine atoms through single covalent bonds. In this layout, the bromine atom serves as an exception to the octet rule, utilizing an expanded valence shell to accommodate ten electrons, which include three bonding pairs and two lone pairs. Each chlorine atom fulfills its octet by maintaining three lone pairs of its own alongside the single shared bond. This arrangement is the most stable because it results in formal charges of zero for every atom involved, representing the most energetically favorable state for the molecule. Consequently, this specific electronic distribution serves as the definitive and most accurate Lewis representation of BrCl₃.

Next: NO₂Cl Lewis structure

External video

• BrCl3 Lewis Structure: How to Draw the Lewis Structure for BrCl3 (Bromine Trichloride) – YouTube • Wayne Breslyn

External links

• https://techiescientist.com/brcl3-lewis-structure/
• https://www.thegeoexchange.org/chemistry/bonding/Lewis-Structures/BrCl3-lewis-structure.html
• https://lambdageeks.com/brcl3-lewis-structure/