the word "ion" comes from the greek word ἰόν, "ion", "going", the present participle of ἰέναι, "ienai", "to go". this term was introduced (after a suggestion by william whewell) by english physicist and chemist michael faraday in 1834 for the then-unknown species that "goes" from one electrode to the other through an aqueous medium. faraday did not know the nature of these species, but he knew that since metals dissolved into and entered a solution at one electrode and new metal came forth from a solution at the other electrode; that some kind of substance has moved through the solution in a current. this conveys matter from one place to the other. in correspondence with faraday, whewell also coined the words "anode" and "cathode", as well as "anion" and "cation" as ions that are attracted to the respective electrodes.