Descriptive chemistry versus theoretical?

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provocative opinion -

Descriptive Chemistry versus Theoretical? Benjamin P. Huddle Roanoke College. Salem, VA 24153 There has heen a great deal of interest expressed lately regarding the return of descriptive chemistry ("facts") to the chemistry curriculum. Articles have appeared in this Journal bemoaning the lack of knowledge of our undergraduate (and graduate?) chemists regarding the facts of chemistry. Many teachers, and nonteachers, wish our introductory courses in chemistry were more narrowly focussed on observations and facts. The ACS Committee on Professional Training now rerommcndi a sophomore-level course on inorzanic chemistry to parallel the traditional organic chemistr; course, with an emphasis on reactions and preparations (which are also reactions, of course), rather than on the laws and theories of the behavior of noncarhon compounds. At Ihannke College, like many colleges, we reach a c&se called 1)wcriutive InorganicChemistr\,and believe hoth adjectives are necessary to describe the course. There must be reasons whv our chemistry curricula, hoth undergraduateand graduare;aeem t u he so heavily weighted with theoretiral chemistrv, nnd I would like to explurc some of those reasons. 1 would assert first of all that we teach theoretical chemistry not because i t is more "glamorous" or more "fun to teach". I helieve most teachers are altruistically motivated and have the best interests of their students at heart. They teach theoretical chemistry because they believe it is important. That is not to deny the importance of facts, hut our experience as teachers tells us that students are all too eager to memorize facts without any understanding a t all. We don't want students who merely regurgitate pearls of wisdom cast by their teachers, hut, without some organizing principles, that is what teaching becomes. Computers can store facts, far more efficiently than can our students; certainly we don't wish to turn our students into automatons. A useful paradigm to help put this into perspective is a summary of the "scientific m e t h o d observations (facts) organizing postulates (laws)

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predictions -theories (to explain) Scientists make observations; they collect facts that describe how nature hehaves. They try to organize those facts by proposing postulates or laws that summarize many observations of how nature hehaves. In an attempt to understand why nature heha\,es that u8ay,scienrists dr\.ise theor;es and mudel,; they rerozni7e that theories mas not he "right" in the same way that observations are "right," and that theories evolve over time and as more observations are made. Moreover, good theories can be used to make predictions about how nature hehaves, predictions about new ohservations that might he made. This completes the circle, leading to more facts, new postulates, revised theories, and so on.

If we do a goodjoh of teaching our students, we try to teach them each aspect of the scientific method. We can't lose sight of the fact that observing nature is where the action is in science; all chemists make observations (collect facts). But neither can we ignore our res~onsihilitvto teach students how to organize their observkions, how to draw conclusions from their data, how to make decisions; good chemists make generalizations (even though they may not he called "laws"), and know the limitations of their generalizations. Nor can we ignore theories. Exceptional chemists propose theories, and in spite of the fact that few of our students will become excentional. we all need the understandine that comes from agood theoretical framework. We also need to he able to differentiate between a good theory and a bad theory, to recognize that all theories have their limitations, and to realize that theories are evolving species. Finally, predictions are hard to teach, hut that is where science advances, and we need to let students know that; great chemists make accurate predictions. Our chemistry curricula, and especially our courses in general chemistry, need to pay attention to each of these aspects. If the current criticism of our traditional freshman chemistry courses is justified, it is justified to the extent that i t points out an imbalance-that we are placing too much emphasis on theory, and not enough emphasis on descriptive chemistry. I helieve the reasons are obvious: teaching facts is time-consuming, and teaching how to make predictions is very difficult. We are told that the total amount of information known doubles every seven years or so. Trying to keep up to date is hard enough trying to assimilate that new knowledge into our courses is almost impossible. We look for short cuts, and one obvious short cut is to minimize descriptive material. On the other hand, we chemists, indeed all scientists, find making good predictions the hardest part of science, and trying to teach that ability to our students is even harder. Thus, there is a tendency to teach both laws and theories as if they were facts. This, 1believe, is the valid criticism of modern chemistry teaching. Theoretical chemistry is integrative. I t makes chemistry make sense. And teaching theoretical chemistry, if it is taught correctly, can he tremendously rewarding. 1know of no greater -iov " in teachine than that which comes when a student's eyes light up, when understading takes place, and students say "1 see!" We de-emphasize that only a t our peril. Teaching science is much harder than teaching "chemistry." I t calls for a balance between facts and laws and theories and predictions. When that balance gets out of whack, teachers riahtfullv remind us of the importance of all the aspects of science-. I hope that the currint debate between "descriptive" and "theoretical" chemistry doesn't swing the pendulum too far in any direction,

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Volume 64

Number 9

September 1967

765