HCl Lewis structure

HCl (hydrogen chloride) has one hydrogen atom and one chlorine atom.

In the HCl Lewis structure, there is a single bond between hydrogen atom and chlorine atom, and on the chlorine atom, there are three lone pairs.

Alternative method: Lewis structure of HCl

Rough sketch

• First, determine the total number of valence electrons

In the periodic table, hydrogen lies in group 1, and chlorine lies in group 17.

Hence, hydrogen has one valence electron and chlorine has seven valence electrons.

Since HCl has one hydrogen atom and one chlorine atom, so…

Valence electrons of one hydrogen atom = 1 × 1 = 1
Valence electrons of one chlorine atom = 7 × 1 = 7

And the total valence electrons = 1 + 7 = 8

Learn how to find: Hydrogen valence electrons and Chlorine valence electrons

• Second, find the total electron pairs

We have a total of 8 valence electrons. And when we divide this value by two, we get the value of total electron pairs.

Total electron pairs = total valence electrons ÷ 2

So the total electron pairs = 8 ÷ 2 = 4

• Third, determine the central atom

Here hydrogen can not be the central atom. Because the central atom is bonded with at least two other atoms, and hydrogen has only one electron in its last shell, so it can not make more than one bond.

Hence, here we have to assume that the central atom is chlorine.

• And finally, draw the rough sketch

Lone pair

Here, we have a total of 4 electron pairs. And one H — Cl bond is already marked. So we have to only mark the remaining three electron pairs as lone pairs on the sketch.

Also remember that hydrogen is a period 1 element, so it can not keep more than 2 electrons in its last shell. And chlorine is a period 3 element, so it can keep more than 8 electrons in its last shell.

Always start to mark the lone pairs from outside atoms. Here, the outside atom is hydrogen. But no need to mark on hydrogen, because hydrogen already has two electrons.

So for chlorine, there are three lone pairs.

Mark the lone pair on the sketch as follows:

Formal charge

Use the following formula to calculate the formal charges on atoms:

Formal charge = valence electrons – nonbonding electrons – ½ bonding electrons

For hydrogen atom, formal charge = 1 – 0 – ½ (2) = 0

For chlorine atom, formal charge = 7 – 6 – ½ (2) = 0

Here, both hydrogen and chlorine atoms do not have charges, so no need to mark the charges.

Final structure

The final structure of HCl has a single covalent bond between the hydrogen and chlorine atoms. In this arrangement, the chlorine atom satisfies the octet rule by possessing three lone pairs of electrons, while the hydrogen atom achieves its stable duet through the shared pair. This configuration results in formal charges of zero for both atoms, ensuring the maximum stability of the molecule. Consequently, this simple linear arrangement represents the most accurate and stable Lewis representation for hydrogen chloride.

Next: H₂ Lewis structure

External video

• How to Draw the Lewis Dot Structure for Hydrogen chloride – YouTube • Wayne Breslyn

External links

• https://www.chemistryscl.com/general/HCl-lewis-structure/index.php
• https://techiescientist.com/hcl-lewis-structure/
• https://socratic.org/questions/what-is-the-lewis-electron-dot-structure-for-a-molecule-of-hydrogen-chloride
• https://lambdageeks.com/hcl-lewis-structure/
• https://www.thegeoexchange.org/chemistry/bonding/hcl-lewis-structure.html