lithiumhalogen

Lithium halides are a family of inorganic compounds with the formula LiX, where X is a halogen: fluorine (F), chlorine (Cl), bromine (Br), or iodine (I). They are typically formed by direct reaction of lithium metal with the halogen, or by metathesis of lithium salts with halide sources.

In the solid state, lithium halides are ionic crystals composed of Li+ and X− ions. The small Li+ ion has high charge density, giving the crystals a high lattice energy and, in the case of LiF, noticeable covalent character due to polarization. They generally have high melting points, with LiF typically the least soluble in water and LiCl, LiBr, and LiI being more soluble. In aqueous solution, Li+ is strongly hydrated, influencing the behavior of these salts in solution and in electrochemical contexts.

Preparation methods include direct halogenation of lithium metal and various salt metatheses that exchange anions to form LiX. They are widely studied for fundamental bonding, solubility trends, and as components in various chemical processes.

Applications vary by halogen. Lithium fluoride (LiF) is used in optics, UV coatings, and as a flux in glass and ceramics; lithium chloride (LiCl) serves as a desiccant and in drying and sample-preparation contexts; lithium bromide (LiBr) is employed as a desiccant in absorption chillers and in some pharmaceutical applications; lithium iodide (LiI) is used as a source of iodide in organic synthesis and, in research, in certain battery-related electrolyte studies.

Safety considerations include moisture sensitivity and potential irritation. They can react with water to form hydrohalic acids and lithium hydroxide, so proper handling, storage in dry conditions, and personal protective equipment are advised.