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Atomic Structure

What is a Hydrogen Chloride Molecule?

Chlorine and hydrogen are both non-metals.
A chlorine atom has 7 electrons in its outer shell.
Chlorine is in group 7 of the periodic table.
A hydrogen atom has 1 electron in its outer shell.
Hydrogen can only form 1 bond.

The hydrogen atom will share its 1 electron
with chlorine to form one covalent bond
and make a hydrogen chloride molecule  (HCl).

This is a picture of a hydrogen chloride molecule.

By sharing the two electrons where the shells touch
the hydrogen atom can count 2 electrons in its outer shell
and the chlorine atom can count 8 electrons in its outer shell.
These full outer shells with their shared electrons are
now stable, and the HCl molecule will not
react further with other chlorine or hydrogen atoms.  

The pair of shared electrons between the
chlorine and hydrogen atoms form a single covalent bond.

The structural formula of a hydrogen chloride molecule is written

There are no ions present (no + or - charges)
in hydrogen chloride gas because the electrons are shared,
not transferred from one atom to another.
Hydrogen chloride does form hydrogen ions and chloride ions
when it is dissolved in water to become hydrochloric acid.

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