Lewis Structure of Br3- (With 5 Simple Steps to Draw!)

I’m super excited to teach you the lewis structure of Br3- ion in just 5 simple steps.

Infact, I’ve also given the step-by-step images for drawing the lewis dot structure of Br3- ion.

So, if you are ready to go with these 5 simple steps, then let’s dive right into it!

Lewis structure of Br3- ion contains two single bonds between each Bromine (Br) atom. All the three Bromine atoms have three lone pairs on it, and the central bromine atom has -1 formal charge.

Let’s draw and understand this lewis dot structure step by step.

(Note: Take a pen and paper with you and try to draw this lewis structure along with me. I am sure you will definitely learn how to draw lewis structure of Br3- ion).

6 Steps to Draw the Lewis Structure of Br3-

Step #1: Calculate the total number of valence electrons

Here, the given ion is Br3^–. In order to draw the lewis structure of Br3^– ion, first of all you have to find the total number of valence electrons present in the Br3^– ion.
(Valence electrons are the number of electrons present in the outermost shell of an atom).

So, let’s calculate this first.

Calculation of valence electrons in Br3^– ion

• For Bromine:

Bromine is a group 17 element on the periodic table. ^[1]

Hence, the valence electrons present in bromine is 7 (see below image).

Hence in a Br3^– ion, 

Valence electrons given by each Bromine (Br) atom = 7
Electron due to -1 charge, 1 more electron is added
So, total number of Valence electrons in Br3^– ion = 7(3) + 1 = 22

Step #2: Select the center atom

While selecting the atom, you have to put the least electronegative atom at the center. 

But here in the Br3- ion, all three atoms are same. So you can simply put any bromine atom at center and place other bromine atoms surrounding it.

Step #3: Put two electrons between the atoms to represent a chemical bond

Now in the above sketch of Br3 molecule, put the two electrons (i.e electron pair) between all the three bromine atoms to represent a chemical bond between them.

These pair of electrons present between the Bromine (Br) atoms form a chemical bond, which bonds all the bromine atoms with each other in a Br3- ion.

Step #4: Complete the octet (or duplet) on outside atoms. If the valence electrons are left, then put the valence electrons pair on the central atom

Don’t worry, I’ll explain!

In the Lewis structure of Br3^– ion, the outer atoms are bromine atoms only.

So now, you have to complete the octet on these bromine atoms (because bromine requires 8 electrons to have a complete outer shell).

Also, only 16 valence electrons of Br3- ion are used in the above structure.

But there are total 22 valence electrons in Br3- ion (as calculated in step #1).

So the number of electrons left to be kept on the central atom = 22 – 16 = 6.

So let’s keep these six electrons (i.e three electron pairs) on the central bromine atom.

Now, let’s move to the next step.

Step #5: Check the formal charge

Now, you have come to the final step and here you have to check the formal charge on Br3- ion. 

For that, you need to remember the formula of formal charge;

Formal charge = Valence electrons – Nonbonding electrons – (Bonding electrons)/2

• For central Bromine:
  Valence electrons = 7 (as it is in group 17)
  Nonbonding electrons = 6
  Bonding electrons = 4
• For outer Bromine:
  Valence electron = 7 (as it is in group 17)
  Nonbonding electrons = 6
  Bonding electrons = 2

Formal charge	=	Valence electrons	–	Nonbonding electrons	–	(Bonding electrons)/2
Central Br	=	7	–	6	–	4/2	=	-1
Outer Br	=	7	–	6	–	2/2	=	0

Let’s keep these charges on the atoms in the above lewis structure of Br3 molecule.

As you can see in the above sketch, there is one -ve charge on the central bromine atom, which indicates the -1 formal charge on the Br3 molecule.

Hence, the above lewis structure of Br3- ion is the stable lewis structure.

Each electron pair (:) in the lewis dot structure of Br3- ion represents the single bond ( | ). So the above lewis dot structure of Br3- ion can also be represented as shown below.

Related lewis structures for your practice:
Lewis Structure of H3O+
Lewis Structure of CH3NO2
Lewis Structure of AsH3
Lewis Structure of SeF6
Lewis Structure of AsF3 

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