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(klōr`īd, klôr`–), chemical compound containing chlorine. Most chlorides are salts that are formed either by direct union of chlorine with a metal or by reaction of hydrochloric acid (a water solution of hydrogen chloridehydrogen chloride,
chemical compound, HCl, a colorless, poisonous gas with an unpleasant, acrid odor. It is very soluble in water and readily soluble in alcohol and ether. It fumes in moist air. It is not flammable, and the liquid is a poor conductor of electricity.
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) with a metal, a metal oxide, or an inorganic base. Chloride salts include sodium chloridesodium chloride,
NaCl, common salt. Properties

Sodium chloride is readily soluble in water and insoluble or only slightly soluble in most other liquids. It forms small, transparent, colorless to white cubic crystals.
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 (common salt), potassium chloridepotassium chloride,
chemical compound, KCl, a colorless or white, cubic, crystalline compound that closely resembles common salt (sodium chloride). It is soluble in water, alcohol, and alkalies.
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, calcium chloridecalcium chloride,
CaCl2, chemical compound that is crystalline, lumpy, or flaky, is usually white, and is very soluble in water. The anhydrous compound is hygroscopic; it rapidly absorbs water and is used to dry gases by passing them through it.
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, and ammonium chlorideammonium chloride
, chemical compound, NH4Cl, a white or colorless, odorless, water-soluble, cubic crystalline salt with a biting taste, commonly known as sal ammoniac.
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. Most chloride salts are readily soluble in water, but mercurous chloridemercurous chloride,
 mercury (I) chloride,
or calomel,
chemical compound, Hg2Cl2, a white crystalline powder, very slightly soluble in water.
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 (calomel) and silver chloridesilver chloride,
chemical compound, AgCl, a white cubic crystalline solid. It is nearly insoluble in water but is soluble in a water solution of ammonia, potassium cyanide, or sodium thiosulfate ("hypo").
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 are insoluble, and lead chloride is only slightly soluble. Some chlorides, e.g., antimony chloride and bismuth chloride, decompose in water, forming oxychlorides. Many metal chlorides can be melted without decomposition; two exceptions are the chlorides of gold and platinum. Most metal chlorides conduct electricity when fused or dissolved in water and can be decomposed by electrolysiselectrolysis
, passage of an electric current through a conducting solution or molten salt that is decomposed in the process. The Electrolytic Process

The electrolytic process requires that an electrolyte, an ionized solution or molten metallic salt, complete an
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 to chlorine gas and the metal. Chlorine forms compounds with the other halogens and with oxygen; when chlorine is the more electronegative element in the compound, the compound is called a chloride. Thus, compounds with bromine and iodine are bromine chloride, BrCl, and iodine chloride, ICI, but compounds with oxygen or fluorine (which are more electronegative than chlorine) are oxides (e.g., chlorine dioxide, ClO2) or fluorides (e.g., chlorine fluoride, ClF) respectively. Many organic compounds contain chlorine, as is indicated by common names such as carbon tetrachloride, methylene chloride, and methyl chloride. However, in the nomenclature system for organic chemistry adopted by the International Union of Pure and Applied Chemistry (IUPAC), the presence in a compound of chlorine bonded to a carbon atom is indicated by the prefix or infix chloro; thus, carbon tetrachloride is tetrachloromethane, methylene chloride is dichloromethane, and methyl chloride is chloromethane.



any one of a group of compounds of chlorine with all elements possessing lower electronegativity, that is, with all metals and nonmetals except oxygen and fluorine. (The chlorides of nitrogen constitute another exception; they are named thus, although the electronegativity of nitrogen is greater than that of chorine.)

Metal chlorides (or salts of hydrochloric acid) are solids, most of which melt or vaporize without decomposition. Most are readily soluble in water except AgCl, CuCl, HgCl2, TlCl, and PbCl2, which are poorly soluble. The chlorides of alkali and alkaline-earth metals are neutral. Solutions of chlorides of other metals are acidic as a result of hydrolysis; for example, AlCl3 + 3H2O = Al(OH)3 + 3HCl.

Chlorides of nonmetals may be gases (HCl), liquids (PCl3), or solids (PCl5). Such compounds are hydrolyzed by water; for example, PCl5 + 4H2O = H3PO4 + 5HCl.

Sodium chloride, potassium chloride, magnesium chloride, and calcium chloride are common in nature (see).

For information on the properties, production, and uses of chlorides, seePOTASSIUM CHLORIDE; SODIUM CHLORIDE; MAGNESIUM CHLORIDE; CALCIUM CHLORIDE; and TITANIUM HALIDE.


A compound which is derived from hydrochloric acid and contains the chlorine atom in the -1 oxidation state.
In general, any binary compound containing chloride.


1. any salt of hydrochloric acid, containing the chloride ion Cl--
2. any compound containing a chlorine atom, such as methyl chloride (chloromethane), CH3Cl
References in periodicals archive ?
That single amino acid change reduced the channel's ability to shuttle chloride ions across the cell membrane by about half.
Researchers at the University of Toronto, under an FHWA contract, developed a new method for predicting chloride ion penetration in bridges and pavements.
Genzyme's research will include the development of high-throughput screens to identify compounds with the potential to improve chloride ion transport or repair the particular protein defect that causes cystic fibrosis in most patients.
Thus, nitrate ions are "exchanged" for natural chloride ions from salt.
The CFTR gene provides instructions for making a channel that transports negatively charged particles called chloride ions into and out of cells.
Cystic fibrosis is caused by a defect in the Cystic Fibrosis Transmembrane Regulator (CFTR) protein, which transports chloride ions across the membrane of epithelial cells lining several organs in the body such as the lungs and the pancreas.
Most scientists believe that mutant versions of cftr encode defective proteins that cannot properly transport chloride ions into lung cells, thus creating a buildup of salt outside them.
Chloride ions reach the reinforcing steel by penetrating the concrete via the pore water and through cracks in the concrete.
Tests being presented are those for the detection of direct bilirubin, magnesium, uric acid, total protein, inorganic phosphorous, glucose, albumin, blood ammonia, simultaneous detection of sodium, potassium and chloride ions, creatine kinase, and creatine kinase MB.
It is the chloride ions that do much of the environmental damage.
They knew that the defect in the cftr gene prevents the channel that normally carries chloride ions into cells from forming.
Sealers and penetrants are used primarily to prevent the corrosion of reinforcing steel caused by aggressive chloride ions when concrete bridge members are exposed to deicers or marine environments.