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(ăn`ī'ən), atom or group of atoms carrying a negative charge. The charge results because there are more electrons than protons in the anion. Anions can be formed from nonmetals by reduction (see oxidation and reductionoxidation and reduction,
complementary chemical reactions characterized by the loss or gain, respectively, of one or more electrons by an atom or molecule. Originally the term oxidation
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) or from neutral acids (see acids and basesacids and bases,
two related classes of chemicals; the members of each class have a number of common properties when dissolved in a solvent, usually water. Properties
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) or polar compounds by ionization. Anionic species include Cl, SO4−−, and CH3COO. Highly colored intermediates in organic reactions are often radical anions (anions containing an unpaired electron). Saltssalt,
chemical compound (other than water) formed by a chemical reaction between an acid and a base (see acids and bases). Characteristics and Classification of Salts

The most familiar salt is sodium chloride, the principal component of common table salt.
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 are made up of anions and cationscation
, atom or group of atoms carrying a positive charge. The charge results because there are more protons than electrons in the cation. Cations can be formed from a metal by oxidation (see oxidation and reduction), from a neutral base (see acids and bases) by protonation, or
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. See ionion,
atom or group of atoms having a net electric charge. Positive and Negative Electric Charges

A neutral atom or group of atoms becomes an ion by gaining or losing one or more electrons or protons.
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An ion that is negatively charged.


a negatively charged ion; an ion that is attracted to the anode during electrolysis


(1) (IDL On the Net) See IDL.

(2) (ION) An NVIDIA graphics platform typically used in Atom-based netbooks. See Intel Atom.

(3) An ion is an atom with fewer or greater electrons than normal as a result of radiation or chemical reaction. A positive ion, called a "cation" (pronounced "cat-eye-en"), has one or more electrons stripped out, which means it has fewer electrons in its electron shells than it has protons in its nucleus. A negative ion, called an "anion" (pronounced "an-eye-en"), is an atom that has one or more electrons forcibly added.

Cations, Anions, Cathodes and Anodes
Although one might think cations are in cathodes and anions are in anodes, the opposite is true. When the terms were coined, the concept was that positive cations were attracted to the negative cathode, and negative anions were attracted to the positive anode.

Batteries Contain Positive and Negative Ions
In a battery, there are positive ions on one side and negative ions on the other. When a conductor is placed in between to complete the circuit, the electrons flow from the negative ions to the positive side where they join the positive ions. See ion deposition.
References in periodicals archive ?
The global Anionic Agricultural Surfactants Market is likely to exhibit steady growth over the forecast period, according to the latest report on Wise Guy Research (WGR).
Modified palatability of commercial products or higher herd dry matter intake or lesser inclusion level of anionic salt would be the outcome for unaffected feed intake (Hutjens, 1991; Oetzel et al., 1991; DeGroot et al., 2010).
The final clay concentration in each tube was ~0.6 g [L.sup.-1], and the PAM concentrations were 0, 20, 40, 60, 80, and 100 mg [L.sup.-1] for anionic and non-ionic PAM, and 0, 10, 20, 30, 40, 50, and 60 mg [L.sup.-1] for cationic PAM.
Polyacrylamides of high commercial interest are copolymers of acrylamide (1, In Figure 1) with sodium or ammonium salts of acrylic acid (4) or 2-acrylamldo tert-butylsulfonic acid (ATBS) (5) to produce anionic polymers or with acryloyloxyethyltrimethylammonlum chloride (AETAC, 6), to produce cationic polymers.
Radical copolymerization of AM and AMPS with a variation in monomeric feed ratio was carried out in aqueous solution in order to obtain copolymers containing anionic groups (Scheme 1).
The formation process of PPy by chemical oxidation has been studied during the polymerization of pyrrole in the presence of anionic surfactants, such as sodium dodecyl sulfate (SDS) and sodiumdodecylbenzenesulfonate (SDBS) (12-15).
In their latest paper, published in Food Chemistry, Bazinet and his colleagues describe how the new system allowed them to simultaneously digest a large protein--[beta]-1actoglobulin, the main component of whey protein--and extract both cationic and anionic peptides from it, including some with activity against high cholesterol and blood pressure.
These drawbacks to anionic exchange columns promoted the development and use of membrane adsorber chromatography.
For clays modified with zwitterion, nonionic and anionic surfactants (TMG, HEC, TRITON X-100, LABSA and SLES), it was seen that the liquid limit and plasticity index increased when surfactant percentage was increased.
They indicated that PSS-794 has a notable ability to selectively target anionic cells in living animals.
It is compatible with most anionic, cationic, and non-ionic dispersants.
In general, surfactants are divided into four classes: amphoteric, with zwitterionic head groups; anionic, with negatively charged head groups; cationic, with positively charged head groups; and nonionic, with uncharged hydrophilic head groups.