Haloid salts: properties, nomenclature, how they are formed, examples

Haloidal salts are also formed by the reaction of a hydracid with a metal. For example: the reaction of magnesium with hydrochloric acid to form magnesium chloride (MgCl 2 ). As can be seen, the chlorides are the most representative haloid salts. However, they are not the only ones.

Halite, sodium chloride in its natural state, is the prime example of a haloid salt. Source: / Public domain

Haloid salts, according to some definitions, comprise compounds that contain halogens in their structure; that is to say: fluorine, chlorine, bromine and iodine, which is why they are considered synonymous with halides or halides.

Properties of haloid salts

Haloid salts are a group of compounds whose properties are difficult to establish. 

Strong ionic bonds

In general, they consist of solids with strong ionic bonds between ions of two elements: M + X  , where M + corresponds to the metal cation, and X  the anion derived from the non-metal.

High melting, boiling and sublimation points

They tend to have very high melting, boiling and sublimation points, precisely due to the strength of their crystalline structure.

Conduction of electricity

In solid state they are poor conductors of electricity, but in aqueous solution when ionized, or when they melt, they become good conductors.


They are crystalline solids that, when fragmented into powder, can turn white. However, many haloid salts can have a different coloration. For example, nickel chloride is green in color, while ferric chloride has a color ranging from green to red.


Most halide salts are soluble in water, with the exception of silver, lead (II) and mercury (I) halides.


Because they are not volatile compounds, haloid salts do not have strong odors. Also, due to their composition, they can have sour, salty, bitter or sweet flavors.

Haloid salts are named by placing the name of the anion with the suffix uro, followed by the name of the metal directly, preceded by the conjunction of . In the event that the metal has more than one valence, the metal is placed with the suffix bear or ico, depending on its valence.

The metal name can also be placed without a suffix and with the oxidation number in parentheses.

For example: iron (III) chloride, or ferric chloride, FeCl 3 .

How are haloid salts formed?

Haloid salts are formed mainly by three reactions: neutralization, reaction of acid with a metal, and the reaction of a metal with a metalloid or a nonmetal acting with a negative valence.

Neutralization reaction

It is the reaction of an acid with a base, producing the salt and a water molecule. For instance:

HCl + NaOH → NaCl + H 2 O

This example was mentioned at the beginning.

Reaction of an acid with a metal

A strong acid can react with a metal, causing a salt and releasing hydrogen (H 2 ). For example: hydrochloric acid reacts with zinc (Zn) to form zinc chloride (ZnCl 2 ):

Zn + HCl → ZnCl 2       + H 2

Combination of a metal with a metalloid or a nonmetal

These haloid salts result from the combination of a metal with a metalloid or a nonmetal other than halogens. For example: in aluminum phosphide, phosphor with valence -3 is combined with aluminum with valence +3. However, this “combination” is due to specific production reactions for each salt.

Uses / applications

Metal halides

Metal halides are used in high intensity lamps, such as modern lamps. They are also used in greenhouses or in rainy climates to supplement natural light. Silver halides are used in film and photographic papers.

Calcium chloride

Appearance of calcium chloride

Calcium chloride is used as a source of calcium in wastewater treatment. It is also used as a source of calcium through its electrolysis. It is used in the treatment of cardiac arrhythmias and in cases of severe hypocalcemia.

Ferric chloride

Ferric chloride is used in wastewater treatment and water purification. It is also used to etch or strip copper and acts as a catalyst in the vinyl chloride synthesis process.

Potassium chloride and bromide

Potassium chloride is used as a fertilizer and in the treatment of hypokalemia or hypokalemia. Potassium bromide, on the other hand, was used as an anticonvulsant, and is currently used in the pharmaceutical industry and as a dressing.

Sodium chloride and sulfide

The crystal structure of sodium chloride, NaCl, a typical ionic compound. The __ purple spheres represent sodium cations, Na +, and the __ green spheres represent chloride anions, Cl−.

Sodium chloride is used as a food flavoring, in preserving meat, as an antiseptic, in severe hyponatremia, etc. Sodium sulfide is used in nuclear reactors in the production of heavy water, in the removal of hairs from hides, and in the manufacture of rubbers, dyes, and paints.

Phosphides and nitrides

Aluminum phosphide is used as a broadband semiconductor and as an insecticide. Meanwhile, gallium nitride is used as a semiconductor.

Examples of haloid salts

Apart from the examples mentioned in the previous section, other haloid salts with their respective formulas and names will be listed below:

-NaCl: Sodium chloride

-KCl: Potassium chloride

-CaCl 2 : Calcium chloride

-MgCl 2 : Magnesium chloride

-CsCl: Cesium chloride

-BaCl 2 : Barium chloride

-FeCl 2 : Ferrous Chloride

-FeCl 3 : Ferric chloride

-NiCl 2 : Nickel chloride

-CuCl: Cuprous chloride

-CuCl 2 : Cupric chloride

-AgCl: Silver chloride

-ZnCl 2 : Zinc chloride

-CdCl 2 : Cadmium chloride

-HgCl 2 : Mercuric chloride

-AlCl 3 : Aluminum chloride

-NaBr: Sodium bromide

-KBr: Potassium bromide

-CsBr: Cesium bromide

-CdBr: Cadmium bromide

-MgBr 2 : Magnesium bromide

-SrBr 2 : Strontium (II) bromide

-KI: Potassium iodide

-NaI: Sodium iodide

-CsI: Cesium iodide

-AlI 3 : Aluminum iodide

-PbI 2 : Lead (II) iodide

-NaF: Sodium fluoride

-LiF: Lithium fluoride

-CaF 2 : Calcium fluoride

-PtF 2 : Platinum (II) fluoride

-NaS 2 : Sodium sulfide

-Li 4 C: Lithium carbide

-Mg 2 C: Magnesium carbide

-AlP: Aluminum phosphide

-Si 3 N 4 : Silicon nitride

-TiN: Titanium nitride

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