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Atomic Structure

What is an Ammonia Molecule?

Nitrogen and hydrogen are both non-metals.
A nitrogen atom has 5 electrons in its outer shell.
Nitrogen is in group 5 of the periodic table.
A hydrogen atom has 1 electron in its outer shell.
Hydrogen can only form 1 bond.

Three hydrogen atoms each share their 1 electron with
nitrogen to form three covalent bonds
and make an ammonia molecule  (NH₃).

This is a picture of an ammonia molecule.

By sharing the two electrons where the shells touch
each hydrogen atom can count 2 electrons in its outer shell
and the nitrogen atom can count 8 electrons in its outer shell.
These full outer shells with their shared electrons
are now stable, and the NH₃ molecule will
not react further with other hydrogen or nitrogen atoms.

The molecule can also be shown
without the circles for the shells.

Note the 3 pairs (6 electrons) shared between the atoms.
Each electron pair is one bond.
This is called a single covalent bond.
Ammonia has three single covalent bonds.

The structural formula of an ammonia molecule is written

There are no ions present (no + or - charges)
in ammonia gas because the electrons are shared,
not transferred from one atom to another.
Ammonia does make some hydroxide ions
when it is dissolved in water to form a weak alkali.

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