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 than the halogen, to make a fluoride, chloride, bromide, iodide, or astatide compound. Many salts are halides. All Group 1 metals form halides with the halogens and they are white solids.

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.

Contents 1 Test for Halide ions 2 Halides in lighting 3 Halide compounds 4 See also 5 References

[edit] Test for Halide ions

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 colour as follow:
AgF - No Precipitate
AgCl - White
AgBr - Creamy (Pale Yellow)
AgI - Yellow

[edit] Halides in lighting

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.

HID (High-intensity discharge) lamps however, contribute highly to light pollution. Sodium-vapor are favored for this reason.

[edit] Halide compounds

Examples of halide compounds are:

• sodium chloride (NaCl)
• potassium chloride (KCl)
• potassium iodide (KI)
• lithium chloride (LiCl)
• copper(II) chloride (CuCl₂)
• chlorine fluoride (ClF)
• Bromomethane (CH₃Br)
• Iodoform (CHI₃)
• silver chloride (AgCl)

[edit] See also

• Salinity
• Functional groups
• Hydrogen halide

[edit] References