BBr3 Lewis Structure in 5 Steps (With Images)

So you have seen the above image by now, right?

Let me explain the above image in short.

BBr3 lewis structure has a Boron atom (B) at the center which is surrounded by three Bromine atoms (Br). There are 3 single bonds between the Boron atom (B) and each Bromine atom (Br).

If you haven’t understood anything from the above image of BBr3 lewis structure, then just stick with me and you will get the detailed step by step explanation on drawing a lewis structure of BBr3.

So let’s move to the steps of drawing the lewis structure of BBr3.

Steps of drawing BBr3 lewis structure

Step 1: Find the total valence electrons in BBr3 molecule

In order to find the total valence electrons in BBr3 molecule, first of all you should know the valence electrons present in boron atom as well as bromine atom.
(Valence electrons are the electrons that are present in the outermost orbit of any atom.)

Here, I’ll tell you how you can easily find the valence electrons of boron as well as bromine using a periodic table.

Total valence electrons in BBr3 molecule

→ Valence electrons given by boron atom:

Boron is a group 13 element on the periodic table. ^[1] Hence the valence electrons present in boron is 3.

You can see the 3 valence electrons present in the boron atom as shown in the above image.

→ Valence electrons given by bromine atom:

Bromine is a group 17 element on the periodic table. ^[2] Hence the valence electrons present in bromine is 7.

You can see the 7 valence electrons present in the bromine atom as shown in the above image.

Hence, 

Total valence electrons in BBr3 molecule = valence electrons given by 1 boron atom + valence electrons given by 3 bromine atoms = 3 + 7(3) = 24.

Step 2: Select the central atom

For selecting the center atom, you have to remember that the atom which is less electronegative remains at the center.

Now here the given molecule is BBr3 and it contains boron atom (B) and bromine atoms (Br).

You can see the electronegativity values of boron atom (B) and bromine atom (Br) in the above periodic table.

If we compare the electronegativity values of boron (B) and bromine (Br) then the boron atom is less electronegative.

So here the boron atom (B) is the center atom and the bromine atoms (Br) are the outside atoms.

Step 3: Connect each atoms by putting an electron pair between them

Now in the BBr3 molecule, you have to put the electron pairs between the boron atom (B) and bromine atoms (Br).

This indicates that the boron (B) and bromine (Br) are chemically bonded with each other in a BBr3 molecule.

Step 4: Make the outer atoms stable

Now in this step, you have to check the stability of the outer atoms.

Here in the sketch of BBr3 molecule, you can see that the outer atoms are bromine atoms.

These outer bromine atoms are forming an octet and hence they are stable.

Also, in step 1 we have calculated the total number of valence electrons present in the BBr3 molecule.

The BBr3 molecule has a total 24 valence electrons and all these valence electrons are used in the above sketch of BBr3.

Hence there are no remaining electron pairs to be kept on the central atom. 

So now let’s proceed to the next step.

Step 5: Check the stability of lewis structure

Now you have come to the final step in which you have to check the stability of lewis structure of BBr3.

The stability of lewis structure can be checked by using a concept of formal charge.

In short, now you have to find the formal charge on boron (B) atom as well as bromine (Br) atoms present in the BBr3 molecule.

For calculating the formal charge, you have to use the following formula;

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

You can see the number of bonding electrons and nonbonding electrons for each atom of BBr3 molecule in the image given below.

For Boron (B) atom:
Valence electrons = 3 (because boron is in group 13)
Bonding electrons = 6
Nonbonding electrons = 0

For Bromine (Br) atom:
Valence electron = 7 (because bromine is in group 17)
Bonding electrons = 2
Nonbonding electrons = 6

From the above calculations of formal charge, you can see that the boron (B) atom as well as bromine (Br) atom has a “zero” formal charge.

This indicates that the above lewis structure of BBr3 is stable and there is no further change in the above structure of BBr3.

In the above lewis dot structure of BBr3, you can also represent each bonding electron pair (:) as a single bond (|). By doing so, you will get the following lewis structure of BBr3.

I hope you have completely understood all the above steps.

For more practice and better understanding, you can try other lewis structures listed below.

Try (or at least See) these lewis structures for better understanding:

About author

Jay Rana

Jay is an educator and has helped more than 100,000 students in their studies by providing simple and easy explanations on different science-related topics. He is a founder of Pediabay and is passionate about helping students through his easily digestible explanations.

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