---
title: "A student investigating the properties of ionic solids compiles the experimental data shown in the table below.  | Compound | Cation | Anion | Interionic distance (\\(\\text{pm}\\)) | Melting point (\\(^\\circ\\text{C}\\)) | | :— | :— | :— | :— | :— | | \\(\\text{MgO}\\) | \\(\\text{Mg}^{2+}\\) | \\(\\text{O}^{2-}\\) | \\(212\\) | \\(2852\\) | | \\(\\text{MgF}_2\\) | \\(\\text{Mg}^{2+}\\) | \\(\\text{F}^-\\)| \\(199\\) | \\(1263\\) |  Which of the following statements correctly compares the lattice energies of \\(\\text{MgO(s)}\\) and \\(\\text{MgF}_2\\text{(s)}\\) and provides the best justification for the difference in their melting points?"
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url: "https://nerd-notes.com/ubq/121483/"
date_modified: "2026-08-23T05:04:48+00:00"
---

# A student investigating the properties of ionic solids compiles the experimental data shown in the table below.

| Compound | Cation | Anion | Interionic distance (\(\text{pm}\)) | Melting point (\(^\circ\text{C}\)) |
| :— | :— | :— | :— | :— |
| \(\text{MgO}\) | \(\text{Mg}^{2+}\) | \(\text{O}^{2-}\) | \(212\) | \(2852\) |
| \(\text{MgF}_2\) | \(\text{Mg}^{2+}\) | \(\text{F}^-\)| \(199\) | \(1263\) |

Which of the following statements correctly compares the lattice energies of \(\text{MgO(s)}\) and \(\text{MgF}_2\text{(s)}\) and provides the best justification for the difference in their melting points?

A student investigating the properties of ionic solids compiles the experimental data shown in the table below.

| Compound | Cation | Anion | Interionic distance (\(\text{pm}\)) | Melting point (\(^\circ\text{C}\)) |
| :--- | :--- | :--- | :--- | :--- |
| \(\text{MgO}\) | \(\text{Mg}^{2+}\) | \(\text{O}^{2-}\) | \(212\) | \(2852\) |
| \(\text{MgF}_2\) | \(\text{Mg}^{2+}\) | \(\text{F}^-\)| \(199\) | \(1263\) |

Which of the following statements correctly compares the lattice energies of \(\text{MgO(s)}\) and \(\text{MgF}_2\text{(s)}\) and provides the best justification for the difference in their melting points?

- **A.** \(\text{MgO}\) has a greater lattice energy than \(\text{MgF}_2\) because the larger \(\text{O}^{2-}\) ion is more polarizable than the \(\text{F}^-\text{ ion}\), resulting in stronger London dispersion forces throughout the crystal lattice.
- **B.** \(\text{MgO}\) has a greater lattice energy than \(\text{MgF}_2\) because the product of the ionic charges is greater in \(\text{MgO}\), resulting in stronger Coulombic attractions that outweigh the effect of its slightly larger interionic distance.
- **C.** \(\text{MgF}_2\) has a greater lattice energy than \(\text{MgO}\) because the shorter interionic distance between \(\text{Mg}^{2+}\) and \(\text{F}^-\) produces stronger Coulombic attractions between adjacent ions.
- **D.** \(\text{MgF}_2\) has a greater lattice energy than \(\text{MgO}\) because each formula unit contains three ions rather than two, requiring more individual ionic interactions to be overcome upon melting.

*The answer key and step-by-step explanation are available to logged-in users at https://nerd-notes.com/ubq/121483/*