\-ion\ (?; 106). [L. -io, acc. -ionem: cf. F. -ion.]
A noun suffix denoting act, process, result of an act or a
process, thing acted upon, state, or condition; as,
revolution, the act or process of revolving; construction,
the act or process of constructing; a thing constructed;
dominion, territory ruled over; subjection, state of being
subject; dejection; abstraction.

\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}.

\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.