From CONCRETE to ABSTRACT in ELEMENTARY CHEMISTRY G . WAKEHAM University of Colorado, Boulder, Colorado
HEORETICAL chemistry, notwithstanding the master and apply a long list of new concepts and hymultitude of its practical applications, is one of potheses, such as the "laws" of Dalton, Charles, Boyle, the most abstract of sciences. Its laws and Gay-Lussac, Henry, definite and multiple proportions, hypotheses are almost entirely deduced or inferred together with the atomic theory, and is then rushed on, from physical observations and are logically incapable with never a chance to get his mental breath, to such of rigid proof. So-called "demonstrations" are merely subjects as ionization, equilibrium, mass action, and individual illustrations of their practical applicability. atomic structure theory, wafted in on the wings of Psychological research seems to show that only a radioactivity. Without doubt the next important highsmall proportion-perhaps one-fifth--of average human school chemistry text which appwrs will include some minds are inherently capable of abstract thought. kind of "elementary" treatment of wave mechanics. Most people are capable of "learning" a certain How does the average student react to this assault number of facts, of reproducing them more or less upon his mentality? Ordinarily he takes refuge in verbalistically, and even of applying them practically verbalism, learning by rote, with hardly a glimmer of to a narrow range of circumstances. But relatively comprehension, the laws and definitions of the text, few are capable of comprehending a philosophical and reproducing them by name, dr. according to their generalization abstracted from observe$ and classified order of presentation in the text, when examined. The slightest disguise of wording or terminology throws him data. In the October, 1933, number of the Journal of completely off the track, and he angrily demands to be Higher Education (p. 365) Elliot R. Downing states: told "what the teacher wants." He may learn to work Mr. Benjamin has shown that it takes two or three weeks for problems by formula in a purely mechanical way, withhigh-school pupils to understand and to gain facility in the out a trace of visualization or insight into the realities application of one of the usual laws or principles of physics so which the problems are intended to illustrate. I t is he can successfully use it to solve problems of the sort that arise in life. The author has similarly shown that it takes three to not fair, he feels, if the teacher sets him problems of six weeks to give a mastery of a principle or group of closely re- types differing in the slightest degree from those in the book, or unfamiliar re-combinations of any k i d . A lated principles in biology. Theoretical chemistry is undoubtedly far more ab- few intelligent students, realizing that they do not stract than either high-school physics or biology, and understand, may labor to some profit, but are more the time required for the mastery of chemical hypothe- likely to rebel and declare that they don't believe a ses by high-school students would be commensurably word of the stuff anyhow. greater. Few teachers seem to realize how many millennia it To what extent has the average elementary chemistry required for the greatest minds of the ages to arrive at textbook adapted itself to these facts? Frankly, not the concepts which we now so light-heatedly take for a t all. On the basis of a slight and often unsatisfactory granted. The very idea of gas as a definite substanceexperimental study of oxygen and hydrogen-and or group of independent substances--did not emerge within a few weeks' time-the student is expected to until van Helmont's time. I t is not at all easy for
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beginning students to visualize a tasteless, odorless, colorless, intangible substance as anything. And yet we plunge them into ideas with which some of the greatest philosophers struggled in vain, and try to lead them to a comprehension of universal principles and vast generalizations on the basis of a very minimum of difficult and often obscure experimental illustrations. I t has been the writer's fate to examine numerous candidates for master's and doctor's degrees in chemistry. Only a small proportion of these students, after from five to seven years of continuous, intensive study of chemistry, have been found to possess anything like an adequate comprehension of the philosophical basis of theoretical chemistry. Their minds are often vast storehouses of empirical facts, but when asked, for example, to illustrate the law of multiple proportion from the fact that the two common oxides of sulfur contain 50 per cent and 60 per cent of oxygen, respectively, they are as likely as not to give the required simple ratio as 5:6 or--even more surprisinglyas 1:2, based on the arithmetical accident that the atomic weight of sulfur is twice that of oxygen. And it is sometimes difficult to get them to see, afterward, that these answers miss the whole point. How, then, can high-school "toot" be expected to understand why the atomic theory was formulated? It is the writer's firm conviction, based on these observations, that every introductory course in chemistrywhether high-school or collegiate--should begin with a study of the more obvious physical properties of the tangible-liquid and solid-elements and their compounds, introducing carefully and gradually the more difficult phenomena of chemical reactions. (The difficult question of the relation between high-school and college chemistry is not the subject of this paper.) Modern chemical theory is based largely upon the quantilatiwc relations involved in chemical reactions. These can be adequately and amply illustrated without any reference to gas laws. The atomic theory can be simply presented upon the basis of The law of definite proportions alone, and this is as far elementary theoretical chemistry need go. Chemical symbols, formulas, equations, and stoichiometrical problems can all be presented on this foundation. There then opens up to the elementary chemistry teacher a wide field of practical applications, industrial processes, and other "cultural" aspects of the science. The high-school or university student who does not intend to major in chemistry, or whose preprofessional prerequisites do not include chemistry, can obtain a reasonably adequate and comprehensive understanding of the subject, sufficient for an intelligent grasp of the chemistry of everyday life. This plan offers a t least two important advantages. First, it revives, in chemistry teaching, a classical pedagogical maxim which has been largely lost sight of: "Proceed from the concrete to the abstract." I t gives the student a broad, factual acquaintance with tangible chemical phenomena before he seriously attacks the difficult field of chemical theory. Second, it meets
the wide demand for a "cultural" course in chemistry, uncomplicated by mathematics-in which the average student is notoriously helpless--and largely freed from the difficult abstractions which a large majority of students are allegedly inherently incapable of comprehending. European education follows, to a certain extent a t least, this plan. Secondary students are given a leisurely course in elementary chemistry, covering a period of several years, in which the chief emphasis is placed upon acquaintance with empirical facts and quantitative relationships which the student himself demonstrates. No comprehensive presentation of chemical theory is attempted until a broad, factual foundation has been laid. Considerable laboratory technic has also been acquired, so that when the crucial experiments underlying chemical theory are presented the student is already familiar with apparatus and methods and can concentrate his attention upon the philosophical inferences of the experimental data. Usually, the beginning chemistry student in America is overwhelmed by a flood of strange, confusing impressionsnew forms of tools and apparatus, an unfamiliar system of weights and measures, a new terminology, fundamental concepts outside the range of his previous experience, philosophical principles of the widest extension passed over with hardly a word of explanation, and the fundamental laws of physics light-heartedly taken for granted as the basis of chemical theory. No wonder his mind quickly becomes, to borrow James's phrase, "a big, buzzing, blooming confusion." A further advantage of this empirical, "cultural" course is that it can be given with i e r y little reference to the fundamental laws of physics, whereas theoretical chemistry consists largely of abstractions from physical laws and data obtained from observations made by means of physical methods. No student should be allowed to attempt a course in theoretical chemistry without having taken a thorough murse in general physics--to which prerequisite should be added a review of grade-school arithmetic and high-school algebra. I t is instructive to compare European and American chemistry textbooks. The preface of Holleman's wellknown text states that "the book is adapted to the needs of the student who is already acquainted with the rudiments of chemistry and it has proved to be especially helpful to the advanced student. . . . . Yet if one compares the contents of almost any American "elementary" or "beginning" text with Holleman, one finds the same immediate plunge into the deep waters of chemical theory which the famous Dutch author and teacher recommends only to students who are "already acquainted with the rudiments." Chemistry will remain a bugbear subject to the average high-school and college student until chemistry teachers have thoroughly resuscitated the ancient but sound maxim: "Proceed from the concrete to the abstract."
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