HCl Lewis Structure in 6 Steps (With Images)

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

Let me explain the above image in short.

HCl lewis structure has one Hydrogen atom (H) and one Chlorine atom (Cl) which contain a single bond between them. There are 3 lone pairs on the Chlorine atom (Cl).

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

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

Steps of drawing HCl lewis structure

Step 1: Find the total valence electrons in HCl molecule

In order to find the total valence electrons in HCl (hydrogen chloride) molecule, first of all you should know the valence electrons present in a single hydrogen 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 hydrogen as well as chlorine using a periodic table.

Total valence electrons in HCl molecule

→ Valence electrons given by hydrogen atom:

Hydrogen is group 1 element on the periodic table. ^[1] Hence the valence electron present in hydrogen is 1.

You can see that only 1 valence electron is present in the hydrogen 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 HCl molecule = valence electrons given by 1 hydrogen atom + valence electrons given by 1 chlorine atom = 1 + 7 = 8.

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 the given molecule is HCl (hydrogen chloride). It has only two atoms, so you can select any of the atoms as a center atom.

Let’s assume the chlorine atom as a central atom (Because we have to keep hydrogen outside in any lewis structure).

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

Now in the HCl molecule, you have to put the electron pairs between the hydrogen atom (H) and chlorine atom (Cl).

This indicates that the hydrogen (H) atom and chlorine (Cl) atom are chemically bonded with each other in a HCl 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 atom.

Here in the sketch of HCl molecule, we have assumed the chlorine atom as a center atom. So the hydrogen is the outer atom.

Hence you have to make the hydrogen atom stable.

You can see in the below image that the hydrogen atom is forming a duplet and hence it is stable.

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

The HCl molecule has a total 8 valence electrons and out of these, only 2 valence electrons are used in the above sketch.

So the number of electrons which are left = 8 – 2 = 6.

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

Now let’s proceed to the next step.

Step 5: Check the octet on the central atom

In this step, you have to check whether the central chlorine atom (Cl) is stable or not.

In order to check the stability of the central chlorine (Cl) atom, we have to check whether it is forming an octet or not.

You can see from the above picture that the chlorine atom is forming an octet. That means it has 8 electrons.

And hence the central chlorine atom is stable.

Now let’s proceed to the final step to check whether the lewis structure of HCl is stable or not.

Step 6: 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 HCl.

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 hydrogen (H) atom as well as chlorine (Cl) atoms present in the HCl 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 HCl molecule in the image given below.

For Hydrogen (H) atom:
Valence electron = 1 (because hydrogen is in group 1)
Bonding electrons = 2
Nonbonding electrons = 0

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
H	=	1	–	2/2	–	0	=	0
Cl	=	7	–	2/2	–	6	=	0

From the above calculations of formal charge, you can see that the hydrogen (H) atom as well as chlorine (Cl) atom has a “zero” formal charge.

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

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

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:

H2 lewis structure	N3- lewis structure
BH3 lewis structure	C2H6 lewis structure
COCl2 lewis structure	BrF5 lewis structure