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anion (ănˈīˌən), 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 reduction) or from neutral acids (see acids and bases) 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). Salts are made up of anions and cations. See ion.
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An ion that is negatively charged.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.


a negatively charged ion; an ion that is attracted to the anode during electrolysis
Collins Discovery Encyclopedia, 1st edition © HarperCollins Publishers 2005


(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.
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References in periodicals archive ?
The uptake of chromate anions at different pH value follows the trend: pH 2 > pH 3 > pH 5 > pH 7 > pH 8.
Now, in a new study appearing in the journal Science, chemists at several institutions, including Caltech and the Jet Propulsion Laboratory, which is managed by Caltech for NASA, as well as the Honda Research Institute and Lawrence Berkeley National Laboratory, have hit on a new way of making rechargeable batteries based on fluoride, the negatively charged form, or anion, of the element fluorine.
NMR titration studies: 1H NMR titrations of L were performed to evaluate its binding affinity for a variety of anions ([F.sup.-], [Cl.sup.-], [Br.sup.-], [I.sup.-], Cl[O.sub.4.sup.-], N[O.sub.3.sup.-], [H.sub.2]P[O.sub.4.sup.-], HS[O.sub.4.sup.-], and S[O.sub.4.sup.2-]) using their tetrabutylammonium salts in DMSO-[d.sub.6].
But if they generate anions and they last long without losing their form, I thought the price was worth it," Kim said.
Due to their toxicity these anions are significant pollutants of soil and water.
For example, Anion gap mEq/L = (Na + K) - (C1+HC03)
Following anion-exchange, these reflections shift toward lower angles, which suggests that the inorganic/ organic inhibitor anions are intercalated in the galleries of LDH layers, in agreement with previous data.
The chain lengths and dipole moments of carboxylic anions were calculated utilizing the Gaussian 98 program [20] and were carried out at the DFT (B3LYP) level of theory with 63-11++G(d,p) basis set.
Effect of Coexisting Anions. The effect of other existing ions on the adsorption capacity was studied by using two different acids for the pH adjustment.
Elevated AG usually represents abnormal accumulation of either endogenous or exogenous unmeasured anions and indicates a primary disorder (a metabolic acidosis), regardless of the pH or the serum bicarbonate (HC[O.sub.3.sup.-]).