Dictionary.com Unabridged (v 1.1) - Cite This Source - Share This

Dictionary.com Unabridged (v 1.1) - Cite This Source - Share This

Dictionary.com Unabridged (v 1.1) - Cite This Source - Share This

American Heritage Dictionary - Cite This Source - Share This

i·on       (ī'ŏn', ī'ən)  Pronunciation Key  n.   An atom or a group of atoms that has acquired a net electric charge by gaining or losing one or more electrons. [Greek ion, something that goes, neuter present participle of ienai, to go; see ei- in Indo-European roots.]

Online Etymology Dictionary - Cite This Source - Share This
ion 

WordNet - Cite This Source - Share This

ion

noun

a particle that is electrically charged (positive or negative); an atom or molecule or group that has lost or gained one or more electrons

The American Heritage Science Dictionary - Cite This Source - Share This

ion       (ī'ən, ī'ŏn')  Pronunciation Key  An atom or a group of atoms that has an electric charge. Positive ions, or cations, are formed by the loss of electrons; negative ions, or anions, are formed by the gain of electrons.

American Heritage New Dictionary of Cultural Literacy, Third Edition - Cite This Source - Share This
ion [(eye-uhn, eye-on)]

An atom that has either lost or gained one or more electrons, so that it has an electrical charge. Ions can be either positively or negatively charged.

American Heritage Stedman's Medical Dictionary - Cite This Source - Share This

ion i·on (ī'ən, ī'ŏn')
n.
An atom or a group of atoms that has acquired a net electric charge by gaining or losing one or more electrons.

Webster's Revised Unabridged Dictionary - Cite This Source - Share This

Ion

I"on\, n. [Gr. ?, neut, of ?, p. pr. of ? to go.] (Elec. Chem.) One of the elements which appear at the respective poles when a body is subjected to electro-chemical decomposition. Cf. Anion, Cation.

Webster's Revised Unabridged Dictionary - Cite This Source - Share This

Ion

I"on\, n. 1. One of the electrified particles into which, according to the electrolytic dissociation theory, the molecules of electrolytes are divided by water and other solvents. An ion consists of one or more atoms and carries a unit charge of electricity, 3.4 x 10^-10 electrostatic units, or a multiple of this. Those which are positively electrified (hydrogen and the metals) are called cations; negative ions (hydroxyl and acidic atoms or groups) are called anions.

Note: Thus, hydrochloric acid (HCl) dissociates, in aqueous solution, into the hydrogen ion, H^+, and the chlorine ion, Cl^-; ferric nitrate, Fe(NO3)3, yields the ferric ion, Fe^+++, and nitrate ions, NO3^-, NO3^-, NO3^-. When a solution containing ions is made part of an electric circuit, the cations move toward the cathode, the anions toward the anode. This movement is called migration, and the velocity of it differs for different kinds of ions. If the electromotive force is sufficient, electrolysis ensues: cations give up their charge at the cathode and separate in metallic form or decompose water, forming hydrogen and alkali; similarly, at the anode the element of the anion separates, or the metal of the anode is dissolved, or decomposition occurs.

2. One of the small electrified particles into which the molecules of a gas are broken up under the action of the electric current, of ultraviolet and certain other rays, and of high temperatures. To the properties and behavior of ions the phenomena of the electric discharge through rarefied gases and many other important effects are ascribed. At low pressures the negative ions appear to be electrons; the positive ions, atoms minus an electron. At ordinary pressures each ion seems to include also a number of attached molecules. Ions may be formed in a gas in various ways.

American Heritage Abbreviations Dictionary 3rd Edition - Cite This Source - Share This

ION Institute of Nutrition