Last updated
IUPAC name
3D model (JSmol)
ECHA InfoCard 100.123.477
EC Number 215-285-9
PubChem CID
Molar mass 67.452
Conjugate acid Chlorous acid
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

The chlorite ion, or chlorine dioxide anion, is ClO
. A chlorite (compound) is a compound that contains this group, with chlorine in oxidation state +3. Chlorites are also known as salts of chlorous acid.

An ion is an atom or molecule that has a non-zero net electrical charge. Since the charge of the electron is equal and opposite to that of the proton, the net charge of an ion is non-zero due to its total number of electrons being unequal to its total number of protons. A cation is a positively charged ion, with fewer electrons than protons, while an anion is negatively charged, with more electrons than protons. Because of their opposite electric charges, cations and anions attract each other and readily form ionic compounds.

Chlorine Chemical element with atomic number 17

Chlorine is a chemical element with symbol Cl and atomic number 17. The second-lightest of the halogens, it appears between fluorine and bromine in the periodic table and its properties are mostly intermediate between them. Chlorine is a yellow-green gas at room temperature. It is an extremely reactive element and a strong oxidising agent: among the elements, it has the highest electron affinity and the third-highest electronegativity, behind only oxygen and fluorine.

The oxidation state, sometimes referred to as oxidation number, describes the degree of oxidation of an atom in a chemical compound. Conceptually, the oxidation state, which may be positive, negative or zero, is the hypothetical charge that an atom would have if all bonds to atoms of different elements were 100% ionic, with no covalent component. This is never exactly true for real bonds.



The free acid, chlorous acid HClO2, is the least stable oxoacid of chlorine and has only been observed as an aqueous solution at low concentrations. Since it cannot be concentrated, it is not a commercial product. The alkali metal and alkaline earth metal compounds are all colorless or pale yellow, with sodium chlorite (NaClO2) being the only commercially important chlorite. Heavy metal chlorites (Ag+, Hg+, Tl+, Pb2+, and also Cu2+ and NH+
) are unstable and decompose explosively with heat or shock. [1]

Chlorous acid chemical compound

Chlorous acid is an inorganic compound with the formula HClO2. It is a weak acid. Chlorine has oxidation state +3 in this acid. The pure substance is unstable, disproportionating to hypochlorous acid (Cl oxidation state +1) and chloric acid (Cl oxidation state +5):

Aqueous solution solution in which the solvent is water

An aqueous solution is a solution in which the solvent is water. It is mostly shown in chemical equations by appending (aq) to the relevant chemical formula. For example, a solution of table salt, or sodium chloride (NaCl), in water would be represented as Na+(aq) + Cl(aq). The word aqueous (comes from aqua) means pertaining to, related to, similar to, or dissolved in, water. As water is an excellent solvent and is also naturally abundant, it is a ubiquitous solvent in chemistry. Aqueous solution is water with a pH of 7.0 where the hydrogen ions (H+) and hydroxide ions (OH-) are in Arrhenius balance (10-7).

Alkali metal Group of highly-reactive chemical elements

The alkali metals are a group (column) in the periodic table consisting of the chemical elements lithium (Li), sodium (Na), potassium (K), rubidium (Rb), caesium (Cs), and francium (Fr). This group lies in the s-block of the periodic table of elements as all alkali metals have their outermost electron in an s-orbital: this shared electron configuration results in their having very similar characteristic properties. Indeed, the alkali metals provide the best example of group trends in properties in the periodic table, with elements exhibiting well-characterised homologous behaviour.

Sodium chlorite is derived indirectly from sodium chlorate, NaClO3. First, the explosively unstable gas chlorine dioxide, ClO2 is produced by reducing sodium chlorate in a strong acid solution with a suitable reducing agent (for example, sodium chloride, sulfur dioxide, or hydrochloric acid).

Sodium chlorate chemical compound

Sodium chlorate is an inorganic compound with the chemical formula NaClO3. It is a white crystalline powder that is readily soluble in water. It is hygroscopic. It decomposes above 300 °C to release oxygen and leave sodium chloride. Several hundred million tons are produced annually, mainly for applications in bleaching paper.

Chlorine dioxide chemical compound

Chlorine dioxide is a chemical compound with the formula ClO2. This yellowish-green gas crystallizes as bright orange crystals at −59 °C. As one of several oxides of chlorine, it is a potent and useful oxidizing agent used in water treatment and in bleaching.

Structure and properties

The chlorite ion adopts a bent molecular geometry, due to the effects of the lone pairs on the chlorine atom, with an O–Cl–O bond angle of 111° and Cl–O bond lengths of 156 pm. [1] Chlorite is the strongest oxidiser of the chlorine oxyanions on the basis of standard half cell potentials. [2]

Bent molecular geometry

In chemistry, the term "bent" can be applied to certain molecules to describe their molecular geometry. Certain atoms, such as oxygen, will almost always set their two (or more) covalent bonds in non-collinear directions due to their electron configuration. Water (H2O) is an example of a bent molecule, as well as its analogues. The bond angle between the two hydrogen atoms is approximately 104.45°. Nonlinear geometry is commonly observed for other triatomic molecules and ions containing only main group elements, prominent examples being nitrogen dioxide (NO2), sulfur dichloride (SCl2), and methylene (CH2).

Lone pair pair of valence electrons that are not shared with another atom; concept used in valence shell electron pair repulsion theory (VSEPR theory) which explains the shapes of molecules

In chemistry, a lone pair refers to a pair of valence electrons that are not shared with another atom and is sometimes called an unshared pair or non-bonding pair. Lone pairs are found in the outermost electron shell of atoms. They can be identified by using a Lewis structure. Electron pairs are therefore considered lone pairs if two electrons are paired but are not used in chemical bonding. Thus, the number of lone pair electrons plus the number of bonding electrons equals the total number of valence electrons around an atom.

IonAcidic reactionE° (V)Neutral/basic reactionE° (V)
Hypochlorite H+ + HOCl + e12 Cl2(g) + H2O1.63ClO + H2O + 2 e → Cl + 2 OH0.89
Chlorite3 H+ + HOClO + 3 e12 Cl2(g) + 2 H2O1.64ClO
+ 2 H2O + 4 e → Cl + 4 OH
Chlorate 6 H+ + ClO
+ 5 e12 Cl2(g) + 3 H2O
+ 3 H2O + 6 e → Cl + 6 OH
Perchlorate 8 H+ + ClO
+ 7 e12 Cl2(g) + 4 H2O
+ 4 H2O + 8 e → Cl + 8 OH


The most important chlorite is sodium chlorite (NaClO2); this is used in the bleaching of textiles, pulp, and paper, however despite its strongly oxidizing nature it is often not used directly being instead used to generate the neutral species chlorine dioxide (ClO2), normally via a reaction with HCl:

Sodium chlorite chemical compound

Sodium Chlorite (NaClO2) is a chemical compound used in the manufacturing of paper and as a disinfectant.

5 NaClO2 + 4 HCl → 5 NaCl + 4 ClO2 + 2 H2O

Other oxyanions

Several oxyanions of chlorine exist, in which it can assume oxidation states of −1, +1, +3, +5, or +7 within the corresponding anions Cl, ClO, ClO
, ClO
, or ClO
, known commonly and respectively as chloride, hypochlorite, chlorite, chlorate, and perchlorate. These are part of a greater family of other chlorine oxides.

An oxyanion, or oxoanion, is an ion with the generic formula A
. Oxyanions are formed by a large majority of the chemical elements. The formulae of simple oxyanions are determined by the octet rule. The corresponding oxyacid of an oxyanion is the compound H
. The structures of condensed oxyanions can be rationalized in terms of AOn polyhedral units with sharing of corners or edges between polyhedra. The phosphate and polyphosphate esters adenosine monophosphate (AMP), adenosine diphosphate (ADP) and adenosine triphosphate (ATP) are important in biology.

Chlorine oxide index of chemical compounds with the same name

Chlorine and oxygen can bond in many ways:

oxidation state−1+1+3+5+7
anion named chloride hypochlorite chlorite chlorate perchlorate
structure Chloride-ion-3D-vdW.png Hypochlorite-3D-vdW.png Chlorite-3D-vdW.png Chlorate-3D-vdW.png Perchlorate-3D-vdW.png

See also

Related Research Articles

Ionic bonding chemical bond involving electron transfer

Ionic bonding is a type of chemical bonding that involves the electrostatic attraction between oppositely charged ions, and is the primary interaction occurring in ionic compounds. It is one of the main bonds along with Covalent bond and Metallic bonding. Ions are atoms that have gained one or more electrons and atoms that have lost one or more electrons. This transfer of electrons is known as electrovalence in contrast to covalence. In the simplest case, the cation is a metal atom and the anion is a nonmetal atom, but these ions can be of a more complex nature, e.g. molecular ions like NH+
or SO2−
. In simpler words, an ionic bond is the transfer of electrons from a metal to a non-metal in order to obtain a full valence shell for both atoms.

Perchloric acid chemical compound

Perchloric acid is a mineral acid with the formula HClO4. Usually found as an aqueous solution, this colorless compound is a stronger acid than sulfuric acid and nitric acid. It is a powerful oxidizer when hot, but aqueous solutions up to approximately 70% by weight at room temperature are generally safe, only showing strong acid features and no oxidizing properties. Perchloric acid is useful for preparing perchlorate salts, especially ammonium perchlorate, an important rocket fuel component. Perchloric acid is dangerously corrosive and readily forms potentially explosive mixtures.

Aqua regia mixture

Aqua regia is a mixture of nitric acid and hydrochloric acid, optimally in a molar ratio of 1:3. Aqua regia is a yellow-orange fuming liquid, so named by alchemists because it can dissolve the noble metals gold and platinum, though not all metals.

The chloride ion is the anion Cl. It is formed when the element chlorine gains an electron or when a compound such as hydrogen chloride is dissolved in water or other polar solvents. Chloride salts such as sodium chloride are often very soluble in water. It is an essential electrolyte located in all body fluids responsible for maintaining acid/base balance, transmitting nerve impulses and regulating fluid in and out of cells. Less frequently, the word chloride may also form part of the "common" name of chemical compounds in which one or more chlorine atoms are covalently bonded. For example, methyl chloride, with the standard name chloromethane is an organic compound with a covalent C−Cl bond in which the chlorine is not an anion.

Sodium hypochlorite chemical compound

Sodium hypochlorite is a chemical compound with the formula NaOCl or NaClO, comprising a sodium cation and a hypochlorite anion. It may also be viewed as the sodium salt of hypochlorous acid. The anhydrous compound is unstable and may decompose explosively. It can be crystallized as a pentahydrate NaOCl·5H
, a pale greenish-yellow solid which is not explosive and is stable if kept refrigerated.

Manganese dioxide chemical compound

Manganese(IV) oxide is the inorganic compound with the formula MnO
. This blackish or brown solid occurs naturally as the mineral pyrolusite, which is the main ore of manganese and a component of manganese nodules. The principal use for MnO
is for dry-cell batteries, such as the alkaline battery and the zinc-carbon battery. MnO
is also used as a pigment and as a precursor to other manganese compounds, such as KMnO
. It is used as a reagent in organic synthesis, for example, for the oxidation of allylic alcohols. MnO
in the α polymorph can incorporate a variety of atoms in the "tunnels" or "channels" between the manganese oxide octahedra. There is considerable interest in α-MnO
as a possible cathode for lithium ion batteries.

Chlorate anion

The chlorate anion has the formula ClO
. In this case, the chlorine atom is in the +5 oxidation state. "Chlorate" can also refer to chemical compounds containing this anion; chlorates are the salts of chloric acid. "Chlorate", when followed by a Roman numeral in parentheses, e.g. chlorate(VII), refers to a particular oxyanion of chlorine.

Hypochlorite anion

In chemistry, hypochlorite is an ion with the chemical formula ClO. It combines with a number of cations to form hypochlorites, which may also be regarded as the salts of hypochlorous acid. Common examples include sodium hypochlorite and calcium hypochlorite.

Chloric acid chemical compound

Chloric acid, HClO3, is an oxoacid of chlorine, and the formal precursor of chlorate salts. It is a strong acid (pKa ≈ −1) and oxidizing agent.

Manganese(II) chloride chemical compound

Manganese(II) chloride describes a series of compounds with the formula MnCl2(H2O)x, where the value of x can be 0, 2, or 4. The tetrahydrate is the most common form of "manganese(II) chloride" and is the tetrahydrate with the formula MnCl2·4H2O. The anhydrous form and a dihydrate MnCl2·2H2O are also known. Like many Mn(II) species, these salts are pink, with the paleness of the color being characteristic of transition metal complexes with high spin d5 configurations.

Sodium perchlorate chemical compound

Sodium perchlorate is the inorganic compound with the chemical formula NaClO4. It is a white crystalline, hygroscopic solid that is highly soluble in water and in alcohol. It usually encountered as the monohydrate. The compound is noteworthy as the most water-soluble of the common perchlorate salts.

In chemical nomenclature, the IUPAC nomenclature of inorganic chemistry is a systematic method of naming inorganic chemical compounds, as recommended by the International Union of Pure and Applied Chemistry (IUPAC). It is published in Nomenclature of Inorganic Mating. Ideally, every inorganic compound should have a name from which an unambiguous formula can be determined. There is also an IUPAC nomenclature of organic chemistry.

An oxyacid, or oxoacid, is an acid that contains oxygen. Specifically, it is a compound that contains hydrogen, oxygen, and at least one other element, with at least one hydrogen

Calcium chlorate is the calcium salt of chloric acid, with the chemical formula Ca(ClO3)2. Like other chlorates, it is a strong oxidizer.

Barium chlorate chemical compound

Barium chlorate, Ba(ClO3)2, is a white crystalline solid, the barium salt of chloric acid. It is an irritant and toxic, as are all soluble barium compounds. It is sometimes used in pyrotechnics to produce a green color. It also finds use in the production of chloric acid.


  1. 1 2 Greenwood, N.N.; Earnshaw, A. (2006). Chemistry of the elements (2nd ed.). Oxford: Butterworth-Heinemann. p. 861. ISBN   0750633654.
  2. Cotton, F. Albert; Wilkinson, Geoffrey (1988), Advanced Inorganic Chemistry (5th ed.), New York: Wiley-Interscience, p. 564, ISBN   0-471-84997-9