---
title: "A student uses the potential-energy curves shown to compare the bonds in two halogen molecules. The zero of potential energy represents atoms that are completely separated from each other.  Which statement best interprets the graph and explains why the relative bond strengths do not follow the relative equilibrium bond lengths?"
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url: "https://nerd-notes.com/ubq/119511/"
date_modified: "2026-08-19T12:40:57+00:00"
---

# A student uses the potential-energy curves shown to compare the bonds in two halogen molecules. The zero of potential energy represents atoms that are completely separated from each other.

Which statement best interprets the graph and explains why the relative bond strengths do not follow the relative equilibrium bond lengths?

A student uses the potential-energy curves shown to compare the bonds in two halogen molecules. The zero of potential energy represents atoms that are completely separated from each other.

Which statement best interprets the graph and explains why the relative bond strengths do not follow the relative equilibrium bond lengths?

![Draw a grayscale graph of potential energy versus internuclear distance. The horizontal axis is labeled \(r\) (pm), extends from 80 to 400, and has marked ticks at 142 and 199. The vertical axis is labeled potential energy (kJ/mol), extends from \(-300\) to \(+300\), and has marked ticks at \(-243\), \(-155\), and 0. A legend maps a solid curve to \(\text{F}_2\) and a long-dashed curve to \(\text{Cl}_2\). Use light gridlines through the marked ticks. Each curve rises steeply above \(+300\) at small separations, descends smoothly to one minimum, and approaches 0 from below at large separations. The solid minimum is exactly at \((142,-155)\); the long-dashed minimum is exactly at \((199,-243)\). Place one open circular marker at each minimum. No other curves, labels, text, or annotations appear.](https://nerd-notes.com/wp-content/uploads/ubq-frq-generated/stem-fig-1-1787143256-dflEre.jpg)

- **A.** The \(\text{F}-\text{F}\) bond is shorter and weaker than the \(\text{Cl}-\text{Cl}\) bond because shorter equilibrium separations always produce shallower potential-energy wells.
- **B.** The \(\text{F}-\text{F}\) bond is shorter and weaker than the \(\text{Cl}-\text{Cl}\) bond because the small \(\text{F}\) atoms place their nonbonding electron pairs close together, increasing repulsion and reducing the stabilization from bond formation.
- **C.** The \(\text{F}-\text{F}\) bond is shorter and stronger than the \(\text{Cl}-\text{Cl}\) bond because the shorter separation increases the attraction between the nuclei and the bonding electrons.
- **D.** The \(\text{Cl}-\text{Cl}\) bond is shorter and stronger than the \(\text{F}-\text{F}\) bond because the lower minimum represents both a smaller equilibrium separation and a larger bond dissociation energy.

*The answer key and step-by-step explanation are available to logged-in users at https://nerd-notes.com/ubq/119511/*