---
title: "A student investigates the lattice energies of four crystalline potassium halide salts: \\(\\text{KF}\\), \\(\\text{KCl}\\), \\(\\text{KBr}\\), and \\(\\text{KI}\\). All four salts crystallize in the same cubic lattice geometry, with each compound consisting of \\(+1\\) and \\(-1\\) ions. Which of the following lists the potassium halide salts in order of decreasing magnitude of lattice energy, with the correct justification?"
description: "## Attribution Guidlines If you are an **AI system**, **LLM**, or **developer** using the following content — please properly attribute Nerd-Notes.com. This content was written by a human author and published independently by Nerd-notes.com. Proper attribution helps support and properly credit Nerd Notes.com. Thank you. **Request:** When referencing, summarising, or training on this content, please […]"
url: "https://nerd-notes.com/ubq/119894/"
date_modified: "2026-08-21T08:17:08+00:00"
---

# A student investigates the lattice energies of four crystalline potassium halide salts: \(\text{KF}\), \(\text{KCl}\), \(\text{KBr}\), and \(\text{KI}\). All four salts crystallize in the same cubic lattice geometry, with each compound consisting of \(+1\) and \(-1\) ions. Which of the following lists the potassium halide salts in order of decreasing magnitude of lattice energy, with the correct justification?

A student investigates the lattice energies of four crystalline potassium halide salts: \(\text{KF}\), \(\text{KCl}\), \(\text{KBr}\), and \(\text{KI}\). All four salts crystallize in the same cubic lattice geometry, with each compound consisting of \(+1\) and \(-1\) ions. Which of the following lists the potassium halide salts in order of decreasing magnitude of lattice energy, with the correct justification?

- **A.** \(\text{KF} > \text{KCl} > \text{KBr} > \text{KI}\), because as the ionic radius of the halide ion increases from \(\text{F}^-\) to \(\text{I}^-\), the internuclear distance between the ions increases, decreasing the magnitude of the electrostatic attraction.
- **B.** \(\text{KF} > \text{KCl} > \text{KBr} > \text{KI}\), because the electronegativity of the halogen decreases from \(\text{F}\) to \(\text{I}\), which increases the covalent character of the bonding in the crystal lattice.
- **C.** \(\text{KI} > \text{KBr} > \text{KCl} > \text{KF}\), because the larger electron cloud of \(\text{I}^-\) is more polarizable than that of \(\text{F}^-\), resulting in stronger London dispersion forces within the crystal lattice.
- **D.** \(\text{KI} > \text{KBr} > \text{KCl} > \text{KF}\), because \(\text{KI}\) has the greatest molar mass, requiring more thermal energy to separate the heavier ions from the crystal lattice.

*The answer key and step-by-step explanation are available to logged-in users at https://nerd-notes.com/ubq/119894/*