n. [ Gr. 'io`n, neut, of 'iw`n, p. pr. of 'ie`nai to go. ] 1. (Elec. Chem.) an atom or goup of atoms (radical) carrying an electrical charge. It is contrasted with neutral atoms or molecules, and free radicals. Certain compounds, such as sodium chloride, are composed of complementary ions in the solid (crystalline) as well as in solution. Others, notably acids such as hydrogen chloride, may occur as neutral molecules in the pure liquid or gas forms, and ionize almost completely in dilute aqueous solutions. In solutions (as in water) ions are frequently bound non-covalently with the molecules of solvent, and in that case are said to be solvated. According to the electrolytic dissociation theory, the molecules of electrolytes are divided into ions by water and other solvents. An ion consists of one or more atoms and carries one unit charges 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. 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. Aluminum and chlorine are elements prepared predominantly by such electrolysis, and depends on dissolving compounds in a solvent where the element forms ions. Electrolysis is also used in refining other metals, such as copper and silver. Cf. Anion, Cation. [ Webster 1913 Suppl. ]

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. [ Webster 1913 Suppl. ]

v. t. (chemistry) to add ions.
Syn. -- . [ WordNet 1.5 ]

n. A region of Western Asia Minor colonized by the Ancient Greeks. [ WordNet 1.5 ]

a. [ L. Ionius. See Ionic. ] Of or pertaining to Ionia or the Ionians; Ionic. -- n. A native or citizen of Ionia. [ 1913 Webster ]

n. 1. (Pros.) (a) A foot consisting of four syllables: either two long and two short, -- that is, a spondee and a pyrrhic, in which case it is called the greater Ionic; or two short and two long, -- that is, a pyrrhic and a spondee, in which case it is called the smaller Ionic. (b) A verse or meter composed or consisting of Ionic feet. [ 1913 Webster ]

2. The Ionic dialect; as, the Homeric Ionic. [ 1913 Webster ]

3. (Print.) Ionic type. [ 1913 Webster ]

a. [ L. Ionicus, Gr. &unr_;, fr. &unr_; Ionia. ] [ 1913 Webster ]

1. Of or pertaining to Ionia or the Ionians. [ 1913 Webster ]

2. (Arch.) Pertaining to the Ionic order of architecture, one of the three orders invented by the Greeks, and one of the five recognized by the Italian writers of the sixteenth century. Its distinguishing feature is a capital with spiral volutes. See Illust. of Capital. [ 1913 Webster ]

Ionic dialect (Gr. Gram.), a dialect of the Greek language, used in Ionia. The Homeric poems are written in what is designated old Ionic, as distinguished from new Ionic, or Attic, the dialect of all cultivated Greeks in the period of Athenian prosperity and glory. --
Ionic foot. (Pros.) See Ionic, n., 1. --
Ionic mode, or
Ionian mode, (Mus.), an ancient mode, supposed to correspond with the modern major scale of C. --
Ionic sect, a sect of philosophers founded by Thales of Miletus, in Ionia. Their distinguishing tenet was, that water is the original principle of all things. --
Ionic type, a kind of heavy-faced type (as that of the following line). [ 1913 Webster ] ☞This is Nonpareil Ionic.

a. (Chem.) Of or pertaining to ions; composed of ions, containing ions, or breaking down into ions when dissolved in a polar solvent; as, an ionic solution will conduct a current of electricity. Opposite of nonionic. [ PJC ]

‖n. [ NL. Cf. Iodine. ] (Bot.) A genus of violaceous plants, chiefly found in tropical America, some species of which are used as substitutes for ipecacuanha. [ 1913 Webster ]

n. (Elec. Chem.) the process of converting neutral atoms or molecules into ions. The process may occur by dissolving an ionic substance in a dissociating solvent, such as water, or by adding or subtracting an electron to or from an atom or molecule. The latter process occurs, for example, in an electron beam in a mass spectrometer and by interaction of substances with ionizing radiation. [ PJC ]

v. t. [ imp. & p. p. Ionized p. pr. & vb. n. Ionizing ] (Physics, Chemistry) To convert (an atom or molecule) into ions, e. g. by dissolving in water, by reaction with acid or alkali, or by interaction with ionizing radiation. See ionization. [ Webster 1913 Suppl. +PJC ]