---
title: "The potential energy curves for two diatomic halogen molecules, \\(\\text{Cl}_2\\text{(g)}\\) and \\(\\text{Br}_2\\text{(g)}\\), as a function of internuclear distance are shown in the graph below.  Which curve corresponds to \\(\\text{Cl}_2\\text{(g)}\\), and which statement provides the correct justification?"
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url: "https://nerd-notes.com/ubq/119725/"
date_modified: "2026-08-21T08:12:09+00:00"
---

# The potential energy curves for two diatomic halogen molecules, \(\text{Cl}_2\text{(g)}\) and \(\text{Br}_2\text{(g)}\), as a function of internuclear distance are shown in the graph below.

Which curve corresponds to \(\text{Cl}_2\text{(g)}\), and which statement provides the correct justification?

The potential energy curves for two diatomic halogen molecules, \(\text{Cl}_2\text{(g)}\) and \(\text{Br}_2\text{(g)}\), as a function of internuclear distance are shown in the graph below.

Which curve corresponds to \(\text{Cl}_2\text{(g)}\), and which statement provides the correct justification?

![A grayscale plot showing Potential Energy on the vertical y-axis versus Internuclear Distance on the horizontal x-axis. The y-axis is labeled 'Potential Energy (kJ/mol)' and has a horizontal dashed zero line near the top. The x-axis is labeled 'Internuclear Distance (pm)' with an arrow to the right. Two distinct curves are plotted: Curve 1 is drawn as a solid black line; it begins high in the positive potential energy region at very short internuclear distance, descends rapidly to a deep potential energy minimum at a smaller internuclear distance, and then rises asymptotically toward the horizontal dashed zero line. Curve 2 is drawn as a dashed black line; it begins at short internuclear distance, descends to a shallower potential energy minimum located at a greater internuclear distance than Curve 1's minimum, and rises asymptotically toward the horizontal dashed zero line. A small legend in the upper-right corner indicates: solid line = Curve 1, dashed line = Curve 2. No other particles, labels, text, or annotations appear.](https://nerd-notes.com/wp-content/uploads/ubq-frq-generated/stem-fig-1-1787299929-bwbYXf.jpg)

- **A.** Curve 2, because \(\text{Br}\) atoms have larger electron clouds than \(\text{Cl}\) atoms, resulting in greater polarizability and a stronger covalent bond.
- **B.** Curve 2, because the bonding electrons in \(\text{Cl}_2\) experience greater electron-electron repulsion, resulting in a longer equilibrium bond length and a less stable molecule.
- **C.** Curve 1, because \(\text{Cl}\) atoms have fewer electron shells than \(\text{Br}\) atoms, which allows the nuclei to be closer to the shared bonding electrons, resulting in a shorter bond length and stronger electrostatic attraction.
- **D.** Curve 1, because \(\text{Cl}_2\) has a higher molar mass than \(\text{Br}_2\), which increases the London dispersion forces between the two bonded atoms and deepens the potential energy well.

*The answer key and step-by-step explanation are available to logged-in users at https://nerd-notes.com/ubq/119725/*