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, or astatide compound. Many salts are halides. All Group 1 metals form halides which 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.
See chloride, bromide, fluoride, and iodide
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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:
For organic compounds containing halides, the Beilstein test is used.
Metal halides are used in high-intensity discharge lamps called metal halide lamps, such as those used in modern street lights. These are more energy-efficient than mercury-vapor lamps, and have much better colour rendition than orange high-pressure sodium lamps. Metal halide lamps are also commonly used in greenhouses or in rainy climates to supplement natural sunlight.
Halides are also used in solder paste, commonly as a Cl or Br equivalent.[1]
Examples of halide compounds are: