(biochemistry) A protein complex or single protein which penetrates a cell membrane and catalyzes the passage of specific ions through that membrane.

(chemistry) any ion containing more than one atom. e.g. sulphate as opposed to sulphide

(chemistry) the reversible process whereby ions are exchanged between a solution and a solid or gel; cation exchange is the process used in a water softener

(chemistry) Used other than figuratively or idiomatically: see hydrogen, ion. ; H⁻ or H⁺

an ionophore

(chemistry) any carbocation containing a tervalent carbon atom

(chemistry) a carbenium ion or any carbocation

(chemistry) Any carbocation obtained by hydrogenation of an alkane.

(chemistry) Any radical that also carries an electric charge; typically, the charge and unpaired electron are associated with the same atom.

(chemistry) Any cation formed by the addition of a proton to the nitrogen or oxygen atom of an amide or derivative.