Question

The boiling points of the elements helium, neon, argon, krypton, and xenon increase in that order. Which of the following statements accounts for this increase?

(A) The London (dispersion) forces increase.
(B) The hydrogen bonding increases.
(C) The dipole-dipole forces increase.
(D) The chemical reactivity increases.
(E) The number of nearest neighbors increases.

Answer 1

The correct statement accounting for the increase in the boiling points of noble gases from helium to xenon is the increase in London (dispersion) forces due to greater polarizability of larger atoms.

Step-by-step explanation:

The increase in boiling points of the elements helium, neon, argon, krypton, and xenon is due to the increase in London (dispersion) forces. These forces become more pronounced as atomic and molecular masses increase, which is related to the polarizability of a substance. Larger, heavier atoms tend to be more polarizable than lighter ones, suggesting the outer electrons can be easily perturbed, creating momentary dipoles that influence intermolecular attraction. This perturbation is lesser in smaller atoms like helium where electrons are held closer to the nucleus. The increase in the molar mass, surface area, and number of electrons leads to stronger London dispersion forces and higher boiling points.