Cl3- 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.

Cl3- lewis structure has three Chlorine atoms (Cl). There are 2 single bonds between each Chlorine atom (Cl). There are 3 lone pairs on all the three Chlorine atom. There is a -1 formal charge on the central Chlorine atom (Cl).

If you haven’t understood anything from the above image of Cl3- lewis structure, then just stick with me and you will get the detailed step by step explanation on drawing a lewis structure of Cl3- ion.

So let’s move to the steps of drawing the lewis structure of Cl3- ion.

Steps of drawing Cl3- lewis structure

Step 1: Find the total valence electrons in Cl3- ion

In order to find the total valence electrons in Cl3- ion, first of all you should know the valence electrons present in a single 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 chlorine using a periodic table.

Total valence electrons in Cl3- ion

→ Valence electrons given by chlorine atom:

Chlorine is group 17 element on the periodic table. ^[1] 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 Cl3- ion = valence electrons given by 3 chlorine atoms + 1 more electron is added due to 1 negative charge = 7(3) + 1 = 22.

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 Cl3. All the three atoms are same, so you can select any of the atoms as a center atom.

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

Now in the Cl3 molecule, you have to put the electron pairs between all three chlorine atoms (Cl).

This indicates that all three chlorine (Cl) atoms are chemically bonded with each other in an Cl3 molecule.

Step 4: Make the outer atoms stable. Place the remaining valence electrons pair on the central atom.

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

Here in the sketch of Cl3 molecule, you can see that the outer atoms are chlorine atoms only.

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 Cl3- ion.

The Cl3- ion has a total 22 valence electrons and out of these, only 16 valence electrons are used in the above sketch.

So the number of electrons which are left = 22 – 16 = 6.

You have to put these 6 electrons on the central chlorine atom in the above sketch of Cl3 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 Cl3.

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 all the chlorine (Cl) atoms present in the Cl3 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 Cl3 molecule in the image given below.

For central Chlorine (Cl) atom:
Valence electrons = 7 (because chlorine is in group 17)
Bonding electrons = 4
Nonbonding electrons = 6

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

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

From the above calculations of formal charge, you can see that the central chlorine (Cl) atom has -1 charge and the outer chlorine atoms has 0 charges.

So let’s keep these charges on the respective atoms in the Cl3 molecule.

This overall -1 charge on the Cl3 molecule is represented in the image given below.

In the above lewis dot structure of Cl3- ion, you can also represent each bonding electron pair (:) as a single bond (|). By doing so, you will get the following lewis structure of Cl3- 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:

PCl2- Lewis Structure	AsO2- Lewis Structure
SBr4 Lewis Structure	BrCl5 Lewis Structure
CFCl3 Lewis Structure	NCl2- Lewis Structure