WHY NOT IONS BEFORE ELECTRONS? COLLIS M. BARDIN Washington Union High School, Fresno, California
WOULD not the introduction of the ionic theory between the discussions of the atomic and electronic theories, rather than after both, as is commonly done, simplify and clarify much of our first semester chemistry work? Classroom trial is one obvious test of value. Results here a t Washington have been wholly favorable. At least, in connection with the rest of our procedure, the shift appears permanently desirable. There was no difficulty encountered in presenting the ionic theory that early. Differences in amount of charge on ions were merely designated as such and indicated in the conventional manner with plus and minus signs, without reference to the unitary character of the charges. We begin our study of chemistry, using water to illustrate the properties of matter. Electrolysis of water leads us to distinguish elements from compounds. When we begin to investigate electrolytes we are already familiar, from that example, with the transfer of electric charge and the accompanyingchemical changes.
Therefore the difference in properties between charged and uncharged atoms does not seem strange. We proceed with our analysis from compounds through ions to the structure of atoms. The electrontheorymust account, as it did historically, for the difference in properties between ion and uncharged atom as well as for the differences between kinds of atoms. In the meantime we recognize from the earliest possible moment that, in the solutions with which we deal forthe most part, ions, rather than molecules, are the significant units. We write equations in the ionic form from the start, a t least wherever the differenceis of any signilicauce, and avoid having to retrace our steps to rewrite in that form in the study of salts, acids, and bases, or later in understanding ionic equilibria. Early familiarity with ions especially facilitates the approach to the modem view of acid-base equilibria. Is the change more than the recognition of the central position of the ionic condition as that most commonly met in chemical reaction?
