LETTERS Good and Bad??? What Is an Element? T o the Editor: To the Editor: The "Gleanings from a Conference" in the March The point raised by E. C. Payne [J. CAEM.EDUC., issue of the JOURNAL OF CHEMICAL EDUCATION are 18, 195 (April, 1941)], namely that the term "chemical broadly significant to teachers of high-school chem- element" needs redefinition in view of our long acistry. May I comment b r i d y on one of these state- quaintance with atomic disintegration, both sponments, namely: "There is reported a general lack of taneous and "artificial," is worthy of study. Howability to think, and an overemphasis on memory of ever, his proposed definition of an element as a subquestions and answers." Of all the teaching devices stance of the second (or third) order of complexity is not in use, the question and answer method is the most uni- a definition, but rather a classification. Moreover, versally used. Other methods, such as the lecture, lec- it refers more properly to the atom than to the element. ture demonstration, and group and individual labPerhaps a more explicit definition might be as foloratory work have their place, hut even in these the lows: A chemical element is a pure substance to which, question and answer technic is important. Testing when it is isolated and purified, each and all of the folprograms quite generally employ this technic. lowing statements apply: .. 1. When subjected to.electron or X-ray diffraction in the Good questions and good answers cannot be overemphasized, if the question is the "psychological solid stat< its lattice is shown to contain but one type of positively charged particle, though this particle may exist in groups basis" of all learning. In a classification of good and relatively widely separated from other groups, and though bad questions, from the standpoint of emphasis, I ncgativc parlirlrs (clcctrons' may also exist in the larricr would include among the former, thought questions, 2. When wbjected to electron t,ornbardmtnt. ~t emits only and among the latter, qu&ions of recall. For ex- a single sct of rhe normal K and I, lines ch:mcteristi,,of elements. ample, questions on the topic of fuels, previously as- If i t decomposes, wholly or partidly, to form one or more other substances or materials, the total resulting material emits under signed, such as. Define a fuel, dBes a fuel give energy, electron bombardment one or more new sets of K and L lines and name the solid, liquid, and gaseous fuels, can be 3. The atomic number as deduced from its K and L radiaoveremphasized. Memory is tested. The purpose is tions by Moseley's law gives i t a place in the periodic table that to find out if the pupil got his lesson, and the price is corresponds t o the properties it shows in its combinations (or to combine) with other elements. approval or disapproval of the teacher. Such approval failure 4. Its constituent partides have a dense positively charged may become the goal rather than chemistry. nucleus, whose charge is p?oportional t o the atomic number, On the other hand, a question such as: Is electricity and a relatively less dense, completely negative atmosphere a fuel, provokes debate and leads to research. To ("shell"). 5 . When excited thermally i t emits a characteristic line answer this question a student must learn something spectrum, peculiarly its own, which is independent of the past about electricity, energy, and fuels, both solid and history of the sample but may vary according to the method fluid. It is a thought question. and conditions of excitation. The spectrum may exhibit rotaWould it not be profitable, particularly to us of your tional or vibrational bands a t low temperatures of excitation or readers who are teaching high-school chemistry, to in absorption spectra, but a t temperatures so high that electronic spectra are observed, the spectral lines cannot be analyzed include in your columns a sample list of good and bad line as belonging to the spectra of two or more other elements, nor questions in chemistry from the standpoint of em- can the spectral terms be divided into sets each belonging to a phasis, different (other) element. GEORGEW. FOWLER 6. Each of its constituent particles is sometimes electrically neutral and sometimes electrically charged, though it may happen that one of these states is the normal condition and the other is attained only by the expenditure of considerable energy.
