Question

unit 3 college board questions
3.
the diagram above is a molecular model of a gaseous diatomic element that is just above its boiling point. intermolecular forces between the gas molecules will cause them to condense into the liquid phase if the temperature is lowered. which of the following best describes how the model is limited in its depiction of the phenomenon?
(a) it does not show how hydrogen bonds are constantly forming, breaking, and reforming, which results in a net force of attraction between the molecules.
(b) it does not show how the interactions between ions and the induced molecular dipoles result in a net force of attraction between the molecules.
(c) it does not show how the interacting permanent dipoles of the molecules result in a net force of attraction between the molecules.
(d) it does not show how the temporary fluctuating dipoles of the molecular electron clouds result in a net force of attraction between the molecules.

Explanation:

• For option A: Hydrogen bonds occur between molecules with \(H\) bonded to \(N\), \(O\), or \(F\). Since it's a diatomic element (not \(H_2O\), \(NH_3\), \(HF\) etc.), hydrogen bonds are not present.
• For option B: The model is of a diatomic element (neutral molecules), not ions. So, interactions between ions and induced molecular dipoles (ion - dipole forces) are not relevant.
• For option C: Diatomic elements (e.g., \(N_2\), \(O_2\)) are non - polar. They do not have permanent dipoles.
• For option D: All molecules (including non - polar diatomic molecules) have London dispersion forces. London dispersion forces arise from temporary fluctuating dipoles in the molecular electron clouds. The model does not show this aspect of intermolecular forces.

Answer:

D. It does not show how the temporary fluctuating dipoles of the molecular electron clouds result in a net force of attraction between the molecules.