In
chemistry
Chemistry is the science, scientific study of the properties and behavior of matter. It is a natural science that covers the Chemical element, elements that make up matter to the chemical compound, compounds made of atoms, molecules and ions ...
, a halide (rarely halogenide) is a
binary chemical compound, of which one part is a
halogen
The halogens () are a group in the periodic table consisting of five or six chemically related elements: fluorine (F), chlorine (Cl), bromine (Br), iodine (I), astatine (At), and tennessine (Ts). In the modern IUPAC nomenclature, this group is ...
atom and the other part is an
element or
radical
Radical may refer to:
Politics and ideology Politics
*Radical politics, the political intent of fundamental societal change
*Radicalism (historical), the Radical Movement that began in late 18th century Britain and spread to continental Europe and ...
that is less
electronegative (or more electropositive) than the halogen, to make a
fluoride
Fluoride (). According to this source, is a possible pronunciation in British English. is an inorganic, monatomic anion of fluorine, with the chemical formula (also written ), whose salts are typically white or colorless. Fluoride salts typ ...
,
chloride,
bromide,
iodide,
astatide
Astatine is a chemical element with the symbol At and atomic number 85. It is the rarest naturally occurring element in the Earth's crust, occurring only as the decay product of various heavier elements. All of astatine's isotopes are short-liv ...
, 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
Fluoride (). According to this source, is a possible pronunciation in British English. is an inorganic, monatomic anion of fluorine, with the chemical formula (also written ), whose salts are typically white or colorless. Fluoride salts typ ...
(),
chloride (),
bromide (),
iodide () and
astatide
Astatine is a chemical element with the symbol At and atomic number 85. It is the rarest naturally occurring element in the Earth's crust, occurring only as the decay product of various heavier elements. All of astatine's isotopes are short-liv ...
(). Such ions are present in all
ionic halide salts.
Halide mineral
Halide minerals are those minerals with a dominant halide anion (, , and ). Complex halide minerals may also have polyatomic anions.
Examples include the following:
*Atacamite
* Avogadrite (K,Cs)BF
*Bararite (β)
*Bischofite
* Brüggenite ...
s contain halides.
All these halides are colourless, high melting crystalline solids having high negative
enthalpies of formation.
Tests
Halide compounds such as
,
and
can be tested with
silver nitrate solution, . The halogen will react with and form a
precipitate, with varying colour depending on the halogen:
*
: no precipitate
[ can solve in water.]
*
: white
*
: creamy (pale yellow)
*
: green (yellow)
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 light
A street light, light pole, lamp pole, lamppost, street lamp, light standard, or lamp standard is a raised source of light on the edge of a road or path. Similar lights may be found on a railway platform. When urban electric power distribution ...
s. These are more
energy-efficient than
mercury-vapor lamps, and have much better
colour rendition
A color rendering index (CRI) is a quantitative measure of the ability of a light source to reveal the colors of various objects faithfully in comparison with a natural or standard light source. Light sources with a high CRI are desirable in ...
than
orange high-pressure sodium lamps. Metal halide lamps are also commonly used in
greenhouse
A greenhouse (also called a glasshouse, or, if with sufficient heating, a hothouse) is a structure with walls and roof made chiefly of Transparent ceramics, transparent material, such as glass, in which plants requiring regulated climatic condit ...
s or in rainy climates to supplement natural
sunlight
Sunlight is a portion of the electromagnetic radiation given off by the Sun, in particular infrared, visible, and ultraviolet light. On Earth, sunlight is scattered and filtered through Earth's atmosphere, and is obvious as daylight when t ...
.
Silver halide
A silver halide (or silver salt) is one of the chemical compounds that can form between the element silver (Ag) and one of the halogens. In particular, bromine (Br), chlorine (Cl), iodine (I) and fluorine (F) may each combine with silver to prod ...
s are used in
photographic film
Photographic film is a strip or sheet of transparent film base coated on one side with a gelatin photographic emulsion, emulsion containing microscopically small light-sensitive silver halide crystals. The sizes and other characteristics of th ...
s and
papers
Paper is a thin, flat material produced by the compression of fibres.
Paper(s) or The Paper may also refer to:
Publishing and academia
* Newspaper, a periodical publication
* ''Paper'' (magazine), an American monthly fashion and culture magazin ...
. 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.
Synthetic
organic chemistry often incorporates halogens into
organohalide compounds.
Compounds
Examples of halide compounds are:
*
Sodium chloride
Sodium chloride , commonly known as salt (although sea salt also contains other chemical salts), is an ionic compound with the chemical formula NaCl, representing a 1:1 ratio of sodium and chloride ions. With molar masses of 22.99 and 35.45 g ...
(NaCl)
*
Potassium chloride
Potassium chloride (KCl, or potassium salt) is a metal halide salt composed of potassium and chlorine. It is odorless and has a white or colorless vitreous crystal appearance. The solid dissolves readily in water, and its solutions have a salt ...
(KCl)
*
Potassium iodide (KI)
*
Lithium chloride (LiCl)
*
Copper(II) chloride ()
*
Silver chloride (AgCl)
*
Calcium chloride ()
*
Chlorine fluoride A chlorine fluoride is an interhalogen compound containing only chlorine and fluorine.
{, class="wikitable"
, -
!
! ClF
! ClF3
! ClF5
, -
, Systematic name
, Chlorine monofluoride
, Chlorine trifluoride
, Chlorine pentafluoride
, -
...
(ClF)
*
Organohalides
**
Bromomethane ()
**
Iodoform ()
*
Hydrogen chloride (HCl)
*
Hydrogen bromide(HBr)
Silicon
*
SiF4 (a gas)
*
SiCl4
*
SiB''r''4
*
SiI4
* SiAt
4
* SiTs
4
See also
*
Salinity
Salinity () is the saltiness or amount of salt dissolved in a body of water, called saline water (see also soil salinity). It is usually measured in g/L or g/kg (grams of salt per liter/kilogram of water; the latter is dimensionless and equal ...
*
Organohalide
*
Hydrogen halide
*
Silver halide
A silver halide (or silver salt) is one of the chemical compounds that can form between the element silver (Ag) and one of the halogens. In particular, bromine (Br), chlorine (Cl), iodine (I) and fluorine (F) may each combine with silver to prod ...
References
{{Authority control
Salts