---
title: "The table below provides information about three crystalline ionic compounds containing ions that are isoelectronic with \\(\\text{Ne}\\).  | Compound | Cation | Anion | |—|—|—| | \\(\\text{NaF}\\) | \\(\\text{Na}^+\\) | \\(\\text{F}^-\\) | | \\(\\text{MgO}\\) | \\(\\text{Mg}^{2+}\\) | \\(\\text{O}^{2-}\\) | | \\(\\text{AlN}\\) | \\(\\text{Al}^{3+}\\) | \\(\\text{N}^{3-}\\) |  Which of the following correctly ranks the compounds in order of decreasing melting point, and provides the best justification?"
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url: "https://nerd-notes.com/ubq/123463/"
date_modified: "2026-09-28T11:59:50+00:00"
---

# The table below provides information about three crystalline ionic compounds containing ions that are isoelectronic with \(\text{Ne}\).

| Compound | Cation | Anion |
|—|—|—|
| \(\text{NaF}\) | \(\text{Na}^+\) | \(\text{F}^-\) |
| \(\text{MgO}\) | \(\text{Mg}^{2+}\) | \(\text{O}^{2-}\) |
| \(\text{AlN}\) | \(\text{Al}^{3+}\) | \(\text{N}^{3-}\) |

Which of the following correctly ranks the compounds in order of decreasing melting point, and provides the best justification?

The table below provides information about three crystalline ionic compounds containing ions that are isoelectronic with \(\text{Ne}\).

| Compound | Cation | Anion |
|---|---|---|
| \(\text{NaF}\) | \(\text{Na}^+\) | \(\text{F}^-\) |
| \(\text{MgO}\) | \(\text{Mg}^{2+}\) | \(\text{O}^{2-}\) |
| \(\text{AlN}\) | \(\text{Al}^{3+}\) | \(\text{N}^{3-}\) |

Which of the following correctly ranks the compounds in order of decreasing melting point, and provides the best justification?

- **A.** \(\text{NaF} > \text{MgO} > \text{AlN}\), because the greatest electronegativity difference between the constituent elements produces the strongest individual ionic bonds.
- **B.** \(\text{NaF} > \text{MgO} > \text{AlN}\), because smaller ionic charges minimize repulsive electron-electron interactions between adjacent cations in the crystal lattice.
- **C.** \(\text{AlN} > \text{MgO} > \text{NaF}\), because \(\text{AlN}\) has the greatest molar mass and total number of protons, resulting in stronger London dispersion forces throughout the solid.
- **D.** \(\text{AlN} > \text{MgO} > \text{NaF}\), because the magnitude of the product of ionic charges (\(|q_1 q_2|\)) is greatest in \(\text{AlN}\), resulting in the strongest Coulombic attractions between ions of similar size.

*The answer key and step-by-step explanation are available to logged-in users at https://nerd-notes.com/ubq/123463/*