Chemical compound composed of a halogen atom and some other element
In chemistry , a halide (rarely halogenide [1] ) is a binary chemical 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.[citation needed ]
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− ).[clarification needed ] 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 .
Tests
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.
Uses
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 .
Silver halides are used in photographic films and papers . When the film is developed , the silver halides which have been exposed to light are reduced to metallic silver, forming an image.
Halides are also used in solder paste , commonly as a Cl or Br equivalent.[3]
Synthetic organic chemistry often incorporates halogens into organohalide compounds.
Compounds
Exhibit of halide minerals in the Museum of Geology, South Dakota
Examples of halide compounds are:
Silicon
See also
References