Question

Why are the boiling points of noble gases very low?

Hint:

{Noble gases = Monoatomic + weak forces} Weak dispersion forces → Very low boiling points.

Answer 1

Concept: Boiling point depends largely on the strength of intermolecular forces between particles. Substances with weak intermolecular attractions require very little energy to separate particles, resulting in low boiling points.
Explanation: Noble gases (He, Ne, Ar, Kr, Xe, Rn) exhibit very low boiling points due to the following reasons:

• Monoatomic nature: Noble gases exist as single atoms rather than molecules, so there are no strong intermolecular interactions like hydrogen bonding or dipole-dipole forces.
• Non-polar atoms: They have completely filled valence shells, making them chemically inert and non-polar.
• Weak van der Waals forces: The only attractive forces present are weak London dispersion forces.
• Low intermolecular attraction: Very little energy is required to separate atoms during boiling.

Trend: Boiling points increase down the group (He → Xe) because atomic size and polarizability increase, strengthening dispersion forces slightly. Conclusion: Thus, noble gases have very low boiling points because they are monoatomic and experience only weak van der Waals forces between atoms.