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Atomic Structure

What is a Water Molecule?

Oxygen and hydrogen are both non-metals.
An oxygen atom has 6 electrons in its outer shell.
Oxygen is in group 6 of the periodic table.
A hydrogen atom has 1 electron in its outer shell.
Hydrogen can only form 1 bond.

Two hydrogen atoms each share their 1 electron
with oxygen to form two covalent bonds
and make a water molecule  (H₂O).

This is a picture of a water molecule.

By sharing the two electrons where the shells touch
each hydrogen atom can count 2 electrons in its outer shell
and the oxygen atom can count 8 electrons in its outer shell.
These full outer shells with their shared electrons
are now stable, and the H₂O molecule will
not react further with other oxygen or hydrogen atoms.

Note the 2 pairs (4 electrons) shared between the atoms.
Each electron pair is one bond.
This is called a single covalent bond.
Water has two single covalent bonds.

The structural formula of a water molecule is written

Note the shape of the water molecule,
with both hydrogens on the same side of the oxygen atom.

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