By Michael Judge. Updated Mar 24, 2022

Copper(I) iodide (CuI) is an ionic solid composed of copper cations (Cu⁺) and iodide anions (I⁻). Its unique properties make it valuable in several industrial processes.

Ionic Compounds

In an ionic bond, one atom donates electrons to another, creating oppositely charged ions that attract each other. This arrangement stabilizes the compound, as seen in everyday table salt (NaCl).

Copper(I) Iodide Overview

CuI crystallizes in a cubic lattice and is the simplest example of a copper(I) halide. The copper center has a +1 oxidation state, indicating it has lost one electron during bond formation.

Physical & Chemical Properties

• Appearance: White crystalline powder.
• Density: 5.7 g cm⁻³.
• Melting point: 606 °C.
• Solubility: Practically insoluble in water.
• Natural occurrence: Marshite.

Industrial Applications

CuI is employed in a range of synthetic chemistry reactions as a catalyst or reagent. Its addition to nylon improves resistance to heat and ultraviolet light. It also serves as a reagent for detecting mercury vapor and has historically been used in cloud‑seeding experiments to induce rainfall.