---
title: "The potential energy curves for three neutral homonuclear diatomic molecules in the gas phase, \\(\\text{N}_2\\text{(g)}\\), \\(\\text{O}_2\\text{(g)}\\), and \\(\\text{F}_2\\text{(g)}\\), are shown in the graph below as a function of internuclear distance.  Which of the following correctly identifies the curve corresponding to \\(\\text{O}_2\\text{(g)}\\) and provides the best justification based on the graph and principles of chemical bonding?"
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url: "https://nerd-notes.com/ubq/123840/"
date_modified: "2026-09-28T12:30:30+00:00"
---

# The potential energy curves for three neutral homonuclear diatomic molecules in the gas phase, \(\text{N}_2\text{(g)}\), \(\text{O}_2\text{(g)}\), and \(\text{F}_2\text{(g)}\), are shown in the graph below as a function of internuclear distance.

Which of the following correctly identifies the curve corresponding to \(\text{O}_2\text{(g)}\) and provides the best justification based on the graph and principles of chemical bonding?

The potential energy curves for three neutral homonuclear diatomic molecules in the gas phase, \(\text{N}_2\text{(g)}\), \(\text{O}_2\text{(g)}\), and \(\text{F}_2\text{(g)}\), are shown in the graph below as a function of internuclear distance.

Which of the following correctly identifies the curve corresponding to \(\text{O}_2\text{(g)}\) and provides the best justification based on the graph and principles of chemical bonding?

![A grayscale line graph displays potential energy in \(\text{kJ/mol}\) on the vertical axis versus internuclear distance in \(\text{pm}\) on the horizontal axis. A horizontal dashed zero line is marked at \(0\text{ kJ/mol}\). Three distinct smooth curves (Curve 1, Curve 2, Curve 3) are plotted. All three curves rise steeply toward positive potential energy at internuclear distances below \(60\text{ pm}\), reach a well minimum at a negative potential energy, and approach \(0\text{ kJ/mol}\) asymptotically as internuclear distance exceeds \(300\text{ pm}\). Curve 1 (solid line) has its minimum at \((110\text{ pm}, -945\text{ kJ/mol})\). Curve 2 (dashed line) has its minimum at \((121\text{ pm}, -498\text{ kJ/mol})\). Curve 3 (dotted line) has its minimum at \((142\text{ pm}, -155\text{ kJ/mol})\). A legend in the upper right identifies: solid line = Curve 1, dashed line = Curve 2, dotted line = Curve 3. No other curves, data points, labels, text, or annotations appear.](https://nerd-notes.com/wp-content/uploads/ubq-frq-generated/stem-fig-1-1790598630-r9LoFw.jpg)

- **A.** Curve 1, because \(\text{O}_2\) has a greater effective nuclear charge than \(\text{N}_2\), which draws the bonding electrons closer to the nuclei and creates the shortest bond distance and greatest bond energy.
- **B.** Curve 3, because the nonbonding electron pairs on the oxygen atoms create significant electrostatic repulsions that weaken the bond, resulting in the longest bond distance and smallest bond dissociation energy.
- **C.** Curve 2, because \(\text{O}_2\) has a bond order of \(2\), resulting in an equilibrium bond length and bond dissociation energy intermediate between \(\text{N}_2\) (bond order \(3\), Curve 1) and \(\text{F}_2\) (bond order \(1\), Curve 3).
- **D.** Curve 2, because the molar mass of \(\text{O}_2\) is greater than that of \(\text{N}_2\) but less than that of \(\text{F}_2\), and covalent bond energy is proportional to molecular mass.

*The answer key and step-by-step explanation are available to logged-in users at https://nerd-notes.com/ubq/123840/*