Charles Keilin
Laney College Oakland, California 94606
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:ourse Designed for the Non-Scientist
In view of the great interest shown recently in the teaching of chemistry for the nonscience major, and of the continuing discussion that centers around the subject, it would he presumptuous to pretend that we a t Laney College have any final answers. But we have given a good deal of thought to the matter and are attempting to design a course based on certain philosophical precepts. There has, of course, been a trend in the teaching of freshman chemistry to iriclude more and more of what had once been reserved exclusively for the sophomore or junior physical chemistry course. Gradually, most of the traditional descriptive features of the freshman course have fallen by the wayside, and i t was inevitable that this trend should eventually extend to the course for non-science majors as well. Now it apparently has, and there are current textbooks that run the gamut from descriptive to theoretical. In order to be able to decide what proportion of each to include in our course, and what relationship they should have to each other, we naturally first tried to decide what we expected our students to get from the course. We discovered very
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early that most of the students have very little mathematical ability or inclination. We aren't greatly disturbed hy this, since we hadn't intended taking a very mathematical approach anyway, hut their mathematical intuition is so weak in some cases, that they have no feeling for the simplest multiplicative relationships. It is all right to say that one beaker weighs 60 grams while another weighs, 20, but quite another matter to say that the first weighs three times as much as the second. At least, they would never think of putting it that way. To them, "heavier" means "so many grams heavier," and not "so many times as heavy." They simply don't understand what a ratio is; not just the term, which after all is not really so important, but the idea. This being the case, it is impossible to discuss any relationship that depends on direct or inverse proportionality, until the basic idea of multiplicative relationships is introduced. This can perhaps most easily be done in the context of a laboratory exercise that introduces the metric system. We would have liked to explore the philosophical implications of science-the impact of science on our lives through the
material benefits i t has made possible, the way i t nas altered our view of the world and man's place in it, and the possible ill effects for mankind which may derive from science. These are matters of concern to everyone, and should be discussed long after technical details have been forgotten. But unfortunately the students in our course are not capable of following UP these ideas, and so we must settle for something less. With these limitations in'mind, we have decided to concentrate on some goals that are important and seem within reach. We want our students to get from the course a feeling for the methods of science, and for the way 'scientists think. Not only is scientific reasoning worth investigating for its own sake, and because it leads to a fuller understanding of the achievements of science, but also because there is a discrepancy between the view held by the public-at-large about what scientists do, and the scientist's own view of his own work. People generally have the feeling, probably as a result of exciting newspaper and television reports about specific discoveries, that a scientist always works a t things that specifically and directly benefit mankind, and that the long-range effects of his work are never far from his thoughts. They do not understand the scientist's enthusiasm for the unexplored, even when, and especially when, he is not sure where his investigations will lead, so that his publicly expressed support of research is prompted in large measure by what might be called an "abstract" interest, which does not always make him the best judge of the wide-ranging effects of his efforts. This is a consideration common to all sciences and scientists, and for that reason, can be treated within the context of any one of them. In view of this objective, we realize that our course will have to he a t least in part theoretical, if only to the extent that i t conveys a feeling for what I have just described. We could easily have been carried away with this idea, and designed a whole year's course around it, but we were, in time, brought down to earth by two considerations. First, our students have relatively low abilities, on the average, a relative lack of alertness and interest, and short attention spans. And second, we have come to realize that, in spite of the heavy emphasis recently placed on theoretical aspects, the "science of chemistry" is only one facet of chemistry. A study of how chemists think does not teach us anything about what nature is, but only about why we think it behaves the way it does. Nature is what i t is, regardless of our abstract conceptions of it, just as human behavior is what i t is, regardless of methods of psychological and sociological testing. Because of these two factors, namely the nature of our students, and our recognition of the fact that chemistry is a view of nature as well as an analytical science, we decided to include a good deal of descriptive material. So we have, as of now, these two main goals: to give our students some feeling for the way chemists approach chemical problems, in order that they might gain some insight into the methods of science, and also perhaps be better equipped to evaluate extrascientific opinions and attitudes of scientists; and secondly, to describe some of the interesting processes in nature that are within the realm of chemistry, in order to provide both a different perspective of nature, and to describe the scope of chemistry. These are, we think, ambitious.
goals, considering the circumstances, but then, almost any goals that mean anything would be ambitious. We have no illusions about reaching everybody, but we hope that everybody capable of getting something from some course, will get something worthwhile from ours. To illustrate the methods of chemistry, we wish to show how the chemist, on the basis of experimental evidence, first draws generalizations from the evidence, and then devises models and theories to explain it. A science, after all, usually develops in this way, and only becomes deductive when its theories become more sophisticated. We feel that the relationship between experimental gas behavior and kinetic theory illustrates this well. We want first to show some sample pressurevolume, volume-temperature, and pressure-temperature data, obtained preferably in class demonstration, then draw generalizations in the form of the gas laws, and finally show how the kinetic theory explains the experimental behavior. We feel that we can, in this way, make a good case for the particle model of matter, one which seems to grow organically during the analysis of the data. The more usual treatment of gases seems to be exactly the opposite. The tenets of the kinetic theory are stated as foregone conclusions, and the experimental evidence is then adduced to confirm the theory. As a result, the student never really understands what is fact and what is theory, or even that one aspect is fact and the other theory. Now, once the relationship between experiment and theory is established, deductive reasoning can easily be illustrated by working in the other direction, using kinetic theory to make further predictions about gas behavior. In this way, we can distinguish between experiment and theory, give an introduction to the behavior of gases, show how generalizations are drawn, illustrate inductive reasoning through model building, and finally, deductive reasoning, all with reference to one system. The treatment is necesarily quite simplified, but the basic ideas are all there. When we have finished, the particle model for matter has been introduced and is ready for further applications, and we have not had to resort to the more traditional approach involving a direct and sudden leap to the particle model on the basis of combining weight data. Now it is certainly true that our approach is not historically correct, and while we don't wish to flout the historical development of the science, because of the perspective it can lend, we prefer to interpret the word "historical" rather loosely. With our students, mixtures of weight and volume arguments lead to unbelievable confusion. Faced with the choice of weight or volume, we decided on volume arguments, because we found that they were more easily understood, and because they offer a good deal more flexibility. Once the particle model has been introduced through gas data, a discussion of combining gas volumes leads fairly simply and directly to Avogadro's Hypothesis. Up to this point, there has been no explicit mention of sample weights. In short, we are more interested in the "spirit" than the letter of the historical approach, because this allows us to present more straightforward arguments that still capture the flavor of historical development. We try, in fact, always to apply simplicit,y as n touchstone. We avoid energy versus entropy arguVolume 46, Number 2, February 1969
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ments, which are not only difficult to follow, but give the impression that some compromise must first be worked out before a system can know what is expected of it,. I think this is a good example of where too close an adherence to historical perspective can lead us astray. Entropy ideas were, it seems, originally applied to chemical reactions in order to explain how some endothermic reactions could he spontaneous. Thus entropy was introduced to correct an original misconception, and has been taught that way ever since-first the misconception, then the correction. While there may he definite advantages to this approach with better students, ours are as likely as not to remember the misconception as correct, and for that reason we avoid the suggestion altogether that the possibility of heat liberation is a criterion for spontaneity. Instead, we want to concentrate solely on the tendency of a system to move spontaneously toward the most stable state. Thus, instead of focusing attention on energy and entropy, we focus it on the overall effect, stability. As a final example of a topic that we are reexamining, I would like to mention the electronic structure of the atom. This is traditionally introduced very early in most beginning courses, in connection with atomic structure in general. We have found that our nonscience students take to it quite readily, and many of them can, after a relatively short time, even write the ground-state orbital configurations for the first twenty elements without a mistake. They do not even question the fact that, in spite of the stated energy order s,p,d,f, the 4s orbital fills before the 3d. Although at first glance, it seemed as though we had scored a great triumph, we soon realized that we had pulled the whole scheme out of thin air, and, not only had i t not come from anywhere, but it was not going anywhere either. As an alternative to this, we have decided to present the subject in a way that is consistent with our overall approach. Our idea is to first discuss some descriptive chemistry of elements and compounds, in order to show them as they are found in nature. After distinguishing on an observational basis between elements and compounds, we will, taking a cue from T h e m study," show some comparative experimental data on heats of phase changes and heats of chemical reactions (this might also he done as a laboratory exercise), and discuss the differences in terms of attractive forces between particles. This introduces the idea of chemical bonding, from which the next logical step might he to build up the left and right sides of the periodic tahle by correlating observed reaction behavior. Now i t might he time to digress for a moment, in order to discuss some of the early experiments that led to the understanding of atomic structure. With this in hand, we could then correlate ohsewed chemical behavior with total number of electrons on the atom and proximity to the nearest inert gas (again taking a cue from
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Journal o f Chemiml Edumtion
"Chemstudy"). Then, we can if we choose cite more evidence which would enable us to develop the idea of electron energy levels in the atom, but if we found that the class waa not responding as well as we had hoped, we could ignore the energy levels completely. It might he argued that by doing this we would be losing the opportunity to show an important regularity in the periodic table, but actually we would already have done that simply by showing that the elements are arranged in order of increasing total number of electrons, and by correlating the arrangement with chemica! behavior and proximity to the inert gases. While the student would then not know that all halogen atoms have one less valence electron, and all alkali metal atoms one more valence electron than atoms of the nearest inert gas, and that by acquiring or losing electrons to become halide or alkali metal ions they are acquiring the ualence electron structure of the nearest inert gas, they would know exactly the same thing for the total electron structure. The point I am trying to make is that it is sometimes possible to illustrate a great deal without resorting to some customary theoretical complexities. I mentioned near the outset that we have two main goals in mind: to give the students a feeling for the way scientists think and reason, and to show chemistry as a way of looking at nature. The second goal implies, to us, a fully descriptive treatment, but since we haven't yet developed this very much, I cannot say a great deal about i t here. We are aware, though, that in our enthusiasm to avoid the mistake of having students memorize lists of meaningless valences, we should not make the equally had mistake of having them memorize lists of amino acids, on the superficial assumption that amino acids are basically more relevant. Finally, I should mention something about our laboratory program. We would like to integrate the lab as much as possible into the course as a whole. It would be best if the students' observations in lab could he incorporated into the lecture treatment, but experience has taught us that we must he careful with the "discovery method." Most students of the caliber we normally have in the course are not capable of sustained interest in a project whose immediate result they cannot see. Those with any interest at all want to know, and probably need to know, what it is they are looking for. They are particularly annoycd by chemical reactions if they do not know what to make of them immediately. At present, the course consists of three one-hour lectures and one two-hour laboratory per week. A possibility might be to introduce an idea through experiment in one lab period, pick it up in lecture the same or the next day, continue the discussion through the week, and then finish the subject, possibly with some sort of experimental verification, during the following laboratory. As you can see, much thought and planning remains to be done.
