BrF3 Lewis Structure

BrF3 Lewis Structure

BrF3 (bromine trifluoride) has one bromine atom and three fluorine atoms. In the lewis structure of BrF3, there are three single bonds around the bromine atom, with three fluorine atoms attached to it. Each fluorine atom has three lone pairs, and the bromine atom has two lone pairs.


Here’s how you can draw the BrF3 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

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

Hence, both bromine and fluorine have seven valence electrons.

Since BrF3 has one bromine atom and three fluorine atoms, so…

Valence electrons of one bromine atom = 7 × 1 = 7
Valence electrons of three fluorine 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 bromine is less electronegative than fluorine, assume that the central atom is bromine.

Therefore, place bromine in the center and fluorines on either side.

  • And finally, draw the rough sketch
BrF3 Lewis Structure (Step 1)

#2 Mark Lone Pairs

Here, we have a total of 14 electron pairs. And three Br — F 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 fluorine is a period 2 element, so it can not keep more than 8 electrons in its last shell.

Always start to mark the lone pairs from outside atoms. Here, the outside atoms are fluorines.

So for each fluorine, there are three lone pairs, and for boron, there are two lone pairs.

Mark the lone pairs on the sketch as follows:

BrF3 Lewis Structure (Step 2)

#3 Mark Charges

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 fluorine atom, formal charge = 7 – 6 – ½ (2) = 0

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

And in the above structure, you can see that the central atom (bromine) forms an octet. Hence, the octet rule is satisfied.

Therefore, this structure is the stable lewis structure of BrF3.

Next: SF2 Lewis Structure

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