Physical properties of the noble gases

Group 0 contains non-metal elements placed in the vertical column on the far right of the periodic table. The elements in group 0 are called the noble gases. They exist as single atoms.

Group 0 is on the far right-hand side of the periodic table

The noble gases show trends in their physical properties.

Boiling points

The noble gases all have low boiling points:

• helium, at the top of group 0, has the lowest boiling point of any element
• boiling point increases going down the group

The boiling points of group 0 elements

This is because, going down group 0:

• the atoms become larger
• the intermolecular forces between the atoms become stronger
• more energy is needed to overcome these forces

Question

Radon is situated below xenon in group 0. Predict the likely boiling point of radon.

Reveal answer

The actual boiling point of radon is -61.7˚C. An estimate would lie midway between -100˚C and -50˚C based on the shape of the graph.

Densities

The density of a substance is its mass per unit volume. For example, a small piece of a substance with a high mass has a high density.

The particles in gases are widely spaced, so the noble gases have low densities:

• helium, at the top of group 0, has the lowest density in the group
• density increases going down the group

The densities of group 0 elements