Chemical properties of the noble gases

Compared to other elements, the noble gases in group 0 are inert - they are extremely unreactive.

Explaining the inertness of noble gases

When elements react, their atoms complete their outer shells by losing, gaining, or sharing electrons. The atoms of noble gases already have complete outer shells. They have no tendency to lose, gain, or share electrons. This is why the noble gases are inert and do not take part in chemical reactions.

The table summarises the electron arrangements of elements in groups 1, 7 and 0. See that:

  • atoms of group 1 and 7 elements have incomplete outer shells (so they are reactive)
  • atoms of group 0 elements have complete outer shells (so they are unreactive)
The electron structures of helium, lithium, fluorine, neon, sodium, chlorine, argon and potassium.

Properties and uses of noble gases

The main properties of the noble gases include:

Many uses of the noble gases are linked to one or more of these properties. Argon is used as a ‘shield gas’ when welding pieces of metal together. Argon is:

  • denser than air, so it stops air getting to the metal
  • inert, so the hot metal cannot oxidise and spoil the weld
Question

Filament lamps contain thin metal wires. These become very hot and glow brightly when an electric current is passed through them. Explain why argon, krypton or xenon are used in these lamps.

A filament lamp

The hot metal wires will burn away if any oxygen from the air is present in the lamp. Argon, krypton and xenon are very unreactive. They replace the air inside the lamp, preventing the metal wire burning away.