---
title: "A student investigates the lattice energies and melting points of four crystalline ionic compounds: \\(\\text{MgO}\\), \\(\\text{CaO}\\), \\(\\text{NaF}\\), and \\(\\text{NaCl}\\). The ionic radii of the constituent ions are given in the table below.  | Ion | Ionic radius (pm) | |—|—| | \\(\\text{Mg}^{2+}\\) | \\(72\\) | | \\(\\text{Ca}^{2+}\\) | \\(100\\) | | \\(\\text{Na}^{+}\\) | \\(102\\) | | \\(\\text{F}^{-}\\) | \\(133\\) | | \\(\\text{Cl}^{-}\\) | \\(181\\) | | \\(\\text{O}^{2-}\\) | \\(140\\) |  Based on Coulomb’s law and the data provided, which of the following correctly ranks the compounds in order of melting point from greatest to least?"
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date_modified: "2026-09-28T11:59:53+00:00"
---

# A student investigates the lattice energies and melting points of four crystalline ionic compounds: \(\text{MgO}\), \(\text{CaO}\), \(\text{NaF}\), and \(\text{NaCl}\). The ionic radii of the constituent ions are given in the table below.

| Ion | Ionic radius (pm) |
|—|—|
| \(\text{Mg}^{2+}\) | \(72\) |
| \(\text{Ca}^{2+}\) | \(100\) |
| \(\text{Na}^{+}\) | \(102\) |
| \(\text{F}^{-}\) | \(133\) |
| \(\text{Cl}^{-}\) | \(181\) |
| \(\text{O}^{2-}\) | \(140\) |

Based on Coulomb’s law and the data provided, which of the following correctly ranks the compounds in order of melting point from greatest to least?

A student investigates the lattice energies and melting points of four crystalline ionic compounds: \(\text{MgO}\), \(\text{CaO}\), \(\text{NaF}\), and \(\text{NaCl}\). The ionic radii of the constituent ions are given in the table below.

| Ion | Ionic radius (pm) |
|---|---|
| \(\text{Mg}^{2+}\) | \(72\) |
| \(\text{Ca}^{2+}\) | \(100\) |
| \(\text{Na}^{+}\) | \(102\) |
| \(\text{F}^{-}\) | \(133\) |
| \(\text{Cl}^{-}\) | \(181\) |
| \(\text{O}^{2-}\) | \(140\) |

Based on Coulomb's law and the data provided, which of the following correctly ranks the compounds in order of melting point from greatest to least?

- **A.** \(\text{CaO} > \text{MgO} > \text{NaF} > \text{NaCl}\)
- **B.** \(\text{CaO} > \text{MgO} > \text{NaCl} > \text{NaF}\)
- **C.** \(\text{MgO} > \text{CaO} > \text{NaCl} > \text{NaF}\)
- **D.** \(\text{MgO} > \text{CaO} > \text{NaF} > \text{NaCl}\)

*The answer key and step-by-step explanation are available to logged-in users at https://nerd-notes.com/ubq/123480/*