BrCl4- 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.

BrCl4- lewis structure has an Bromine atom (Br) at the center which is surrounded by four Chlorine atoms (Cl). There are 4 single bonds between the Bromine atom (Br) and each Chlorine atom (Cl). There are 2 lone pairs on the Bromine atom (Br) and 3 lone pairs on all the four Chlorine atoms (Cl).

If you haven’t understood anything from the above image of BrCl4- lewis structure, then just stick with me and you will get the detailed step by step explanation on drawing a lewis structure of BrCl4- ion.

So let’s move to the steps of drawing the lewis structure of BrCl4- ion.

Steps of drawing BrCl4- lewis structure

Step 1: Find the total valence electrons in BrCl4- ion

In order to find the total valence electrons in BrCl4- ion, first of all you should know the valence electrons present in bromine atom as well as chlorine 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 bromine as well as chlorine using a periodic table.

Total valence electrons in BrCl4- ion

→ Valence electrons given by bromine atom:

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

→ Valence electrons given by chlorine atom:

Chlorine is group 17 element on the periodic table. ^[2] Hence the valence electrons present in chlorine is 7.

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

Hence, 

Total valence electrons in BrCl4- ion = valence electrons given by 1 bromine atom + valence electrons given by 1 chlorine atom + 1 more electron is added due to 1 negative charge = 7 + 7(4) + 1 = 36.

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 ion is BrCl4- ion and it contains bromine atom (Br) and chlorine atoms (Cl).

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

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

So here the bromine atom (Br) is the center atom and the chlorine atoms (Cl) are the outside atoms.

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

Now in the BrCl4 molecule, you have to put the electron pairs between the bromine atom (Br) and chlorine atoms (Cl).

This indicates that the bromine (Br) and chlorine (Cl) are chemically bonded with each other in a BrCl4 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 BrCl4 molecule, you can see that the outer atoms are chlorine atoms.

These outer chlorine 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 BrCl4- ion.

The BrCl4- ion has a total 36 valence electrons and out of these, only 32 valence electrons are used in the above sketch.

So the number of electrons which are left = 36 – 32 = 4.

You have to put these 4 electrons on the central bromine atom in the above sketch of BrCl4 molecule.

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 BrCl4.

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 bromine (Br) atom as well as chlorine (Cl) atoms present in the BrCl4 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 BrCl4 molecule in the image given below.

For Bromine (Br) atom:
Valence electron = 7 (because bromine is in group 17)
Bonding electrons = 8
Nonbonding electrons = 4

For Chlorine (Cl) atom:
Valence electron = 7 (because chlorine is in group 17)
Bonding electrons = 2
Nonbonding electrons = 6

Formal charge	=	Valence electrons	–	(Bonding electrons)/2	–	Nonbonding electrons
Br	=	7	–	8/2	–	4	=	-1
Cl	=	7	–	2/2	–	6	=	0

From the above calculations of formal charge, you can see that the bromine (Br) atom has -1 charge, while the chlorine atom has 0 charge.

So let’s keep these charges on the respective atoms in the BrCl4 molecule.

This overall -1 charge on the BrCl4 molecule is represented in the image given below.

In the above lewis dot structure of BrCl4- ion, you can also represent each bonding electron pair (:) as a single bond (|). By doing so, you will get the following lewis structure of BrCl4- ion.

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:

ICN Lewis Structure	P2H4 Lewis Structure
SI6 Lewis Structure	CBr2F2 Lewis Structure
SiH3- Lewis Structure	AsBr3 Lewis Structure