BrO2- Lewis structure

BrO₂^– (bromite) has one bromine atom and two oxygen atoms.

In the BrO₂^– Lewis structure, there is one double bond and one single bond around the bromine atom, with two oxygen atoms attached to it. The oxygen atom with a double bond has two lone pairs, the oxygen atom with a single bond has three lone pairs, and the bromine atom has two lone pairs.

Also, there is a negative (-1) charge on the oxygen atom with a single bond.

Alternative method: Lewis structure of BrO₂^–

Rough sketch

• First, determine the total number of valence electrons

In the periodic table, bromine lies in group 17, and oxygen lies in group 16.

Hence, bromine has seven valence electrons and oxygen has six valence electrons.

Since BrO₂^– has one bromine atom and two oxygen atoms, so…

Valence electrons of one bromine atom = 7 × 1 = 7
Valence electrons of two oxygen atoms = 6 × 2 = 12

Now the BrO₂^– has a negative (-1) charge, so we have to add one more electron.

So the total valence electrons = 7 + 12 + 1 = 20

Learn how to find: Bromine valence electrons and Oxygen valence electrons

• Second, find the total electron pairs

We have a total of 20 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 = 20 ÷ 2 = 10

• Third, determine the central atom

We have to place the least electronegative atom at the center.

Since bromine is less electronegative than oxygen, assume that the central atom is bromine.

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

• And finally, draw the rough sketch

Lone pair

Here, we have a total of 10 electron pairs. And two Br — O bonds are already marked. So we have to only mark the remaining eight 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 oxygen 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 oxygens.

So for each oxygen, 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 (4) = +1

For each oxygen atom, formal charge = 6 – 6 – ½ (2) = -1

Here, both bromine and oxygen atoms have charges, so mark them on the sketch as follows:

The above structure is not a stable Lewis structure because both bromine and oxygen atoms have charges. Therefore, reduce the charges (as below) by converting lone pairs to bonds.

Convert a lone pair of the oxygen atom to make a new Br — O bond with the bromine atom as follows:

Final structure

The final structure of BrO₂^– consists of a central bromine atom connected to two oxygen atoms. Within this layout, bromine utilizes an expanded valence shell to minimize formal charges, resulting in one double bond to one oxygen and a single bond to the second oxygen. The bromine atom satisfies its electronic requirements by maintaining two lone pairs alongside these three bonding pairs. The double-bonded oxygen atom fulfills its octet with two lone pairs, while the single-bonded oxygen carries three lone pairs. This specific configuration is the most stable resonance contributor because it results in a formal charge of zero for the bromine and the double-bonded oxygen, leaving the necessary -1 charge on the more electronegative single-bonded oxygen. Accordingly, this electronic distribution serves as the definitive and most accurate Lewis representation of the bromite ion.

To complete the representation, draw square brackets around the entire Lewis structure and place a “-” or “-1” sign as a superscript outside the upper right bracket. This notation signifies that the negative charge is a property of the whole ion.

Next: PBr₅ Lewis structure

External video

• How to Draw the Lewis Dot Structure for BrO2 – – YouTube • Wayne Breslyn

External links

• https://www.thegeoexchange.org/chemistry/bonding/Lewis-Structures/BrO2-lewis-structure.html
• https://topblogtenz.com/bro2-lewis-structure-molecular-geometry-shape-hybridization/
• https://www.chemistryscl.com/general/BrO2–lewis-structure/index.php
• https://lambdageeks.com/bro2-lewis-structure/
• https://socratic.org/questions/what-is-the-lewis-dot-structure-for-bro-2-and-what-are-the-formal-charges-on-eac