Group 0: The Noble Gases

Introduction to Noble Gases

The noble gases make up Group 0 of the periodic table. These elements include helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), and radon (Rn). They are often called inert gases because they are very unreactive.

This low reactivity is due to their full outer electron shell. Unlike other elements, noble gases have a complete set of electrons in their outermost shell, which makes them stable and unlikely to gain, lose, or share electrons. For example, helium has two electrons filling its first shell, making it very stable. Neon has eight electrons filling its second shell, also making it stable.

Physical Properties

• All noble gases are colourless and odourless in their natural state.
• They have very low boiling points, which means they exist as gases at room temperature.
• They are non-flammable, so they do not catch fire or support combustion.

For example, helium boils at −269 °C, which is much lower than most other elements, so it remains a gas under normal conditions.

Chemical Properties

• Noble gases have very low chemical reactivity due to their full outer electron shells.
• They exist as monatomic gases, meaning each gas particle is a single atom, not molecules.
• They do not normally form compounds with other elements under standard conditions.

For instance, neon and argon rarely form compounds, unlike elements in other groups such as the halogens or alkali metals. However, some heavier noble gases like xenon and krypton can form compounds under special conditions, but this is beyond the basic GCSE scope.

The full outer shell means noble gases have little tendency to react because they do not need to gain or lose electrons to become stable. This contrasts with elements that have incomplete outer shells and are more reactive.

Learning example: Helium’s full outer shell means it does not react with oxygen to form compounds like many other gases do. This is why helium balloons do not react or explode easily.

Uses of Noble Gases

• Lighting: Neon is used in neon lights, producing bright coloured light when an electric current passes through the gas.
• Inert atmosphere for welding: Argon is used to provide an inert atmosphere during welding to prevent metals from reacting with oxygen or nitrogen in the air.
• Filling balloons: Helium is used to fill party balloons because it is lighter than air and non-flammable, making it safer than hydrogen.
• Specialized uses: Xenon is used in some specialized lighting and medical imaging applications.

These uses take advantage of the noble gases’ low reactivity and physical properties such as low density and non-flammability.

For instance, if a helium balloon has a volume of 5.0 dm³ and the density of helium is 0.18 g/dm³, then the mass of helium in the balloon is calculated as mass = density × volume = 0.18 g/dm³ × 5.0 dm³ = 0.9 g.