---
title: "The ions \\(\\text{O}^{2-}\\), \\(\\text{F}^{-}\\), \\(\\text{Na}^{+}\\), and \\(\\text{Mg}^{2+}\\) each contain \\(10\\text{ electrons}\\) with the ground-state electron configuration \\(1s^2\\,2s^2\\,2p^6\\). Which of the following lists the ions in order of decreasing ionic radius and provides the correct explanation?"
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url: "https://nerd-notes.com/ubq/120162/"
date_modified: "2026-08-21T16:02:41+00:00"
---

# The ions \(\text{O}^{2-}\), \(\text{F}^{-}\), \(\text{Na}^{+}\), and \(\text{Mg}^{2+}\) each contain \(10\text{ electrons}\) with the ground-state electron configuration \(1s^2\,2s^2\,2p^6\). Which of the following lists the ions in order of decreasing ionic radius and provides the correct explanation?

The ions \(\text{O}^{2-}\), \(\text{F}^{-}\), \(\text{Na}^{+}\), and \(\text{Mg}^{2+}\) each contain \(10\text{ electrons}\) with the ground-state electron configuration \(1s^2\,2s^2\,2p^6\). Which of the following lists the ions in order of decreasing ionic radius and provides the correct explanation?

- **A.** \(\text{O}^{2-} > \text{F}^{-} > \text{Na}^{+} > \text{Mg}^{2+}\), because the anions occupy more electron shells than the cations.
- **B.** \(\text{O}^{2-} > \text{F}^{-} > \text{Na}^{+} > \text{Mg}^{2+}\), because the increasing nuclear charge exerts a stronger attraction on the valence electrons.
- **C.** \(\text{Mg}^{2+} > \text{Na}^{+} > \text{F}^{-} > \text{O}^{2-}\), because ions with higher nuclear charge have greater electron shielding.
- **D.** \(\text{Mg}^{2+} > \text{Na}^{+} > \text{F}^{-} > \text{O}^{2-}\), because cations experience greater electron-electron repulsions in their valence shells.

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