The Noble Gases

• The elements in group 18 are known as the noble gases (formerly, the inert gases).

• The noble gases have the following properties:

• They are non-metals.

• They exist as individual atoms.

• They have very low melting and boiling points (all are gases at room temperature).

• They have full valence shells (all have eight valence electrons, except helium, which has two).

• They are chemically very unreactive (only xenon, krypton and argon have been found to form compounds).

The elements in group 18 are known as the noble gases.