Lewis structure

Lewis structure of HCl

8 valence electrons. One Cl-H single bond, with three lone pairs on Cl.

Molecule or ion

HClHydrogen chloride

Linear

Cl: 1 sigma bond, 3 lone pairs

i

Two atoms always lie on a line. Many books describe the H-Cl bond as an overlap of the H 1s and a Cl 3p orbital without hybridisation.

8 valence electrons

Formal charges: none

Cl has 7 valence electrons. It uses one in one single bond to H, so six are left as three lone pairs.
Steric number = one sigma bond + three lone pairs = 4, so Cl is sp³ hybridised.
Four electron pairs point to the corners of a tetrahedron (tetrahedral electron geometry). With only two atoms, the molecule itself is a straight line.
Two atoms always lie on a straight line, so there is no bond angle.
The two atoms are different, so the bond is polar and so is HCl.

Working

How to draw it

Count the valence electrons: Cl 7 + H 1 = 8 valence electrons, 4 pairs.
Put Cl in the middle and join it to the other atom with single bonds.
Give each outer atom lone pairs until it has an octet (H needs only two electrons), then put any electrons left over on the central atom.
Result: one Cl-H single bond, with three lone pairs on Cl.
Formal charge = valence electrons − lone pair electrons − number of bonds. Here: none.

Class 11, Chapter 4 Chemical Bonding and Molecular Structure.

Questions

How many valence electrons are in HCl?

Cl 7 + H 1 = 8 valence electrons, 4 pairs.

What are the formal charges in the Lewis structure of HCl?

Every atom has a formal charge of zero.

How many lone pairs are in the Lewis structure of HCl?

3 in all, 3 of them on the central Cl.