Halides

A halide is a binary compound, of which one part is a halogen atom and the other part is an element or radical that is less electronegative (or more electropositive) than the halogen, to make a fluoride, chloride, bromide, iodide, astatide, or theoretically tennesside compound. The alkali metals combine directly with halogens under appropriate conditions forming halides of the general formula, MX (X = F, Cl, Br or I). Many salts are halides; the hal- syllable in halide and halite reflects this correlation. All Group 1 metals form halides that are white solids at room temperature.

A halide ion is a halogen atom bearing a negative charge. The halide anions are fluoride (F⁻), chloride (Cl⁻), bromide (Br⁻), iodide (I⁻) and astatide (At⁻). Such ions are present in all ionic halide salts. Halide minerals contain halides.

All these halides are colourless, high melting crystalline solids having high negative enthalpies of formation.

Halide compounds such as KCl, KBr and KI can be tested with silver nitrate solution, AgNO₃. The halogen will react with Ag⁺ and form a precipitate, with varying colour depending on the halogen:

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