Henry A. Bent North Carolina State University Raleigh. 27607
Uses of History in Teaching Chemistry
"History is bunk" ( 1 ) . The past vields the present in understandable vet unnredictablk wais. Futurisk is futile. The past is prologue--to infinitely many futures. "History reveals much but teaches nothing" (2)-worth knowing on most chefiistry examinations. Spectrum of Uses A sense of history is-
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Useless in taking the GRE exam. Seldom useful in teaching engineering students. Sometimes useful in teaching chemistry majors. Frequently useful in teaching liberal arts students Always useful in writing texts. Consider the fourth point first. The Cultural Divide (3) Most liberal arts students aren't comfortable with the concept per and dimensional ratios-the latter word stems from the Latin reri, to think-and, hence. with the exact sciences. Percent, dens~ty,roncentration, molar mass, nflinity. accrl~~ration, differential coefficients, and partial deriv:itn.es are hard to comprehend. Per permeates science and perplexes non-scientists. Three arithmetical operations-Ambition, Distraction, and Uglification, Lewis Carroll called them-are easy. The fourth operation-Derision, when and how is: difficult, even "irrational." It divides people into two cultures: those who've conquered it and those who've been conquered by it. Ratios make Exact Sciences exact And exacting. Ratios stand behind all theories of measurement, units, dimensions, scales-and beyond most concrete-operationalists. They go right to the heart, Chaucer noted in 1391, of the "ahilite to lerne science2 touching noumhers and proporciouns" (4). Most students in introductory chemistry courses would probably agree with the ancient commentator (5) There irnothing in Euclid's Elements [or Chemistry] Of a more subtile invention.. . Than the doctrine of [Multiple]Proportions. Even simple proportions-simple once seen-are cult to formulate, starting from scratch.
diffi-
Transformation of Chemical Transformations Dehydrating a colored hydrate and rehydrating its anhydrous salt in Chem I is fun. Dull by comparison is determination of the masses ml and mz of the hydrate and the anhydrous salt. Doubly difficult for many students is formulation of the hydrate decomposition law: ml/mn = e, a constant. And impossible for most students, unaided, is solution of this "elementary" problem of multiple proportions: Given the law rnllrnz = e (a known number) and the formula weights of the anhydrous salt and water, calculate the hydrate's formula. 462 1 Joornal of Chemical Education
What Can We Do for Ratia-Deaf Students? Fact 40% are not formal-operational (6). a% at Fact A(%)=---at-0 at at t = forcmg conditions (tutorials, remedial programs, learning centers) JZ >> 0 (fac.effort/student/term large) at At = 1-2 semesters a% Conjeet- 0, < = Anything we can do! we a( To paraphrase Gibbs, if we are to have any success teaching chemistry to ratio-deaf students-if chemistry courses for non-scientists are to be fun, even easy, eye-opening, and mind-stretching, rather than dull, hard, back-breaking, and ego-bruising-it will probably he because we have learned (like Faraday, in his public lectures) to avoid mathematical difficulties. An historical approach to chemical concepts offers students relief from preoccupation with ratio-laden arguments. It offers also, for authors, a "sure guarantee against an incorrect or illogical sequence" (7). Historical Fidelity Saves Time, Avoids Errors Modern introductory texts often devote many pages to developing the entropy-Gihbs energy and sigma-pi formalisms. Pedagogically it's more efficient, physically more insightful, philosophically more accurate to use directly the law of mass action. Carnot's theorem. and van't Hoff's model of the tetrahedral atom. "Proofs" bffered in textbooks for a theorv. notes Boltzmann. are much less convincine than the fact that the theory's con$equences are splendidly confirmed bv. experience. . I exthooks err in fact, logic, and conception, somrtimt!~simultanro~~sly: Kthylene is planar with bond angles of 120° tnr.aust. cnrbon is hyhridiled cp'. In fact. ethylene's hrmd angles are nor 120". The molecule would, in anv event, he plannr, even were carbon hybridized b p (planar F2CO has LFCF 109'). And, not toget the cart (theory) hefore the horse (experiment),carbon's hybridization in ethylene is derermined hy rir., calculated fnnn) observed bond angles, not vice-versa. A knowledge of the history of chemistry would help authors avoid making, also, such ill-informed statements as
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The Braggs showed That sodium chloride Is an ionic compound
Boyle showed that P X V = constant
In fact, the Braggs a t first had no notion NaCl might he viewed as an compound" term),l And Boyle initially did not see "his law" in his data, which were collected for another purpose: to show that "the spring of air" (the Presented in a Symposium organized by Dr. Leonard Fine on the m e topicpicat the Fourth Biennial Conference on Chemical Education, Madison, Wisconsin, August 11,1916. I am indebted to Dr. Norman Craig for this observation.
concept "pressure of a gas" having not yet been invented (8)) was sufficient to support a column of mercury 29 in. high. Similarly, a knowledge of the genetic development of thermodynamics might prevent authors of physical chemistry texts from suggesting, for example, that The thermodynamic equation
( a ~ ~ a= vT(JPI~T)V )~ -P Shows that for ideal gases ( a ~ ~ a= vo ) ~
In fact, the second equation is used to obtain the first one. Science's Syntax T h e difficulty with an elaborately articulated subject like thermodynamics is that, as Howard Nemerov has said of difficult poetry (9) The syntatical resources lOf a laneuaeel " .. . Can get the unwary practitioner Into very ridiculous situations. Facts encoded yield scientific principles. Principles decoded yield scientific facts. Decoding a fact encoded should yield the fact identically.
Encoding: Decoding:
Games People Play (Theory for Theory's Sake) AGO = -RT In Q,* Q,, = In-' (-AG'IRT) = In-' (In Q,,)
Smith, of course, is the man whose name is Smith. Tabulated thermodynamic data, Laws, Theories, and Principles are to users sources, to creators summaries of information. Recurrent Revisionism Because it is easier to go from principles to properties than from properties to principles; because it is easier to think convergently than divergently; because it is easier to use a language than to create one, it seems.most natural to replace historical development by logical derivation. Easy Alchemy In the textbook-classroom Alembic, Theories are transformed. Simple summaries of information Become exalted sources, Divorced from base aspects Of human commitment and conduct. Science in history is risky, insecure, inductive reasoning, from uro~erties to ~rinciples.It uses facts aggressively, to -. . capture concepts. Science in textbooks is safe, dependable, deductive reasoning, from principles to properties. It uses facts passively, to illustrate ideas. Science in Textbooks Is History reversed: It is Time's, Logic's And Psychology's Arrow Inverted. Advanced Mis-Placement Chemistry Science in "high-level" texts, particularly, isPRINCIPLES before properties. ANSWERS before questions. THEORY before facts. ATOMIC PHYSICS before chemical periodicity. TELLING before showing. LECTURES without demonstrations.
Produced is a new "descriptive chemistry", with tragicomic consequences. T o he taken on faith and memorized uncritically are quantum number rules, atomic orbital shapes, molecular orbital diagrams, hybridization geometries, the basic relations of thermodynamics, and other deeply formaloperational topics of interest to ambitious authors. The poor students, in Mach's phrase, have been taught too much. They are overstuffed yet undernourished. Their thoughts creep timidly After words, principles, formulae, Constantly by the same paths. What they have acquired Is a spider's web of thoughts Too weak to furnish supports, But complicated enough To produce confusion (10). Even the best and the brightest confuse packing-case vermiculite for rearent-erade bromine (11)and on advanced" placement examinations regularly write "PCOz" for the formula of potassium carbonate, "Ld" for lead (12).
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Historical Roots of Ineptness Ineutitude in modern education in science stems, believes N. R. camphell, from an anxiety, inherited from 19th century ~hilosoohers,to conceal the role of imagination in scientific discoveiy. "Scientists complain of the lack of appreciation of scientific knowledge," continues Campbell, "What else can they expect if they offer to the world only the dry hones of knowledge from which the breath has departed?" (13). Telling always seems easier than sbowing-if less interesting, and memorable. Indeed, if we remembered everything we've been told, we'd be so smart we couldn't stand ourselves (14).
Texts contain page after page, curricula course after course of telling. As more and more is taught, less and less is shown. Mathematical formulas replace historical examples. Marks on a hlark1)onrd rrplwe revitions seen in thr Iahhatory. I rrvd~tis yiwn for entering The Kingdom of ( h d . J < r r d r r \ for attending 1.errur~ron The Kingd~mid C < , d .
1 Lectures
KINGDOM
KINGDOM
GOD
GOD
Truth in Packaging Science institutionalized is the truth as we see it carefully repackaged. Science in textbooks Is science sanitized. I t is the truth but not the whole of truth. Active innredients that might spoil the dazzling effect of a display of Ggic have been removed. History is an antidote to the view thus nenerated that science is asimplr, imprrwnnl thing drri&l,lt. I y logic . from clear and distinct ideas (15 I . Historical perspectives can show the interplay in science of facts, logic, and ideas (Fig. 1). Facts incubated ("horizontally") hatch into ideas that, acted upon ("vertically") produce facts. The scientific enterprise benefits when, from a sense of history, citizens realize that periods of incubation in science may be measured in decades not days. Volume 54, Number 8, August 1977 1 463
AN
HISTORIC CYCLE Method") Concepts Theories
1"Darwin'r
Induction Encoding Explaining Generalizing
Theorizing Fact Enlargement
(1
Deduction Decoding Predicting Particularizing Theory Testing and Refinement
Experiments Facts Figure 1. Historical cycle in science.
The Genetic PrinciDle \Vhrre scientifir in\wtigations actunlly hegin with fnrts or i(inls-is diiticult to determinr. Chrmiral urthorlux\. holds that chemistry is an "experimental science." The inference is that chemical concepts and theories are hased on experimental data. ~uhversiveto that view is the X-rated suggestion that, based on a received hypothesis (advocated by Boyle and Newton), Dalton selectively sought out examples of the Law of Multiple Proportions from among data not always nicely supportive of his personal views. Where the teaching of science should hegin is, in one view, easily stated: Ontogeny should recapitulate history "We should let students retrace the great steps of the mental evolution of the human race" (16). It is not economical, says Mach, to teach directly (to the concrete operational) science's "economical" end result: its formal mathematical equations. The most economical way of learning starts with uneconomical understanding (10). Instruction should start with visual examples and imaginative demonstrations and evolve slowly into a historical treatment of the suhiect. Onlv when students have mastered problems in their concrete a i d historical'contexts, continues Mach, can they understand abstract equations. Mach, says Blackmore, was an historian from need not love. He used history to make the present, not the past, understandable (10). Each epoch, in fact, acts upon the other: the resent creates to a decree its own antecedents; and antecedents help to create the present (Fig. 2). Chemists, also (like Mach), need to he historians, to place in perspective aggressive knowledge claims of other disciplines.
HISTORY: P U R E A N D APPLIED
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Two Complementary Activities
The
present illuminater the past, t h e part the present Each alters t h e other PAST
Antecedents* identified in historical studies
Antecedents* used in
(,
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PRESENT
'Factual, conceptual, ethical..behavioral Figure 2. Interplay of past and present. 464 / Jouml of Chemical Education
teaching and research
Dirac's Dire Pronouncement "The underlying physical laws necessary for the mathematical theory of a large part of physics a n d the whole of chemistry are. . . thus completely known. . ."So wrote Dirac in 1929 (emphasis added) (17). Dirac was difficult to ignore. His sentence was widely quoted. It appeared in the prefaces of several chemistry texts. There was one catch, however. Continued Dirac in a second, seldom cluoted sentence-". . . the difficultv is onlv that the exact applirsfion uf these Iqunntum mrchnnicall Inws Ivadi to equationi much roo complicated to he soluhle." Fortunately, Chemists h u e solutions to such problems. Those solutions were aptly, if unwittingly, described by Dirac in his next sentence: "It therefore becomes desirable that approximate practical methods of applying quantum mechanics should be developed [emphasis added] which can lead to an explanation of the main features of complex atomic svstems lsuch as molecules and chemicallv reactive svstemsl dithout too much computation." Same Approximate, Practical Quantum-Mechanical Models Tetrahedral Atom Atom, Molecule Acid, Base Functional Groups Periodic Table Solvated Ions Mobile Equilibrium Chemical Bond "In Princlple" May Be Impractical Problems needing computers with more components than there are nrotons and neutrons in the universe are. notes Donald E. Knurh, for all prartiral purposes insolul~le.Certain simole known to he solvahle in finiw time . .n r o l h n s in 1w1c " will never he solved in our lifetime, continues Knuth, regardless of how clever people become or how many resources are committed to the project. Birchi's Theorem (1960) No reasonable algorithm (One not needing a computer with more components than there are protons and neutrons in the universe) Will ever be able to decide truth or falsity For arbitrarily given statements (Not yet as complicated as those of arithmetic) Of length 617 or more. To print the wavefunction for an iron atom would require for ink and paper, observed Douglas Hartree some years ago, more matter than there is in the universe. Limlts of Reason "Do not ask the . ~hvsicist " for the annle . or the atom." said Whitehead. "The mathematical mind lhistorv shows1 could not discover dynamic-electricity," remarks Faraday, "nor electro-magnetism, nor magneto-electricity, or even suggest them; though when once discovered by the experimentalist, it can take them up with extreme facility" (18)
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Waste Mechanics History shows that efforts to derive chemistry from mechanics, of Newton or SehrBdinger,give large yields of uigor without redeeming rigor.
Chemistry is more complicated than physics. A match dropped Is physia.
A match struck Is chemistry.
Free fall is easier to describe, mathematically, then combustion. History shows that the acid test and basic source of chemical theow is the test tube. Out of the test tube came oxvgen. chemical periodicity, structural theory, and most methi& of chemical synthesis.
RECURRENTCYCLE Confidence New Instruments
Enlarged Experience Unfulfilled Ex~ectationr Growing Skepticism Self-criticism Rearrerrments
HQ = EYI Computers Humility Figure 3. Daws 10 knowledge.
Chemistry is consistent with hut not predicted by quantum mechanics. Chemistry stands to quantum mechanics as the present does to the past. Out of the test tube come products in quantum mechanically understandable yet unpredictable ways. "Postdiction" is an advance,nonetheless,for physical theory from the situation in the days of classical mechanics, though less of a leap forward than anticipated in 1929. Oscillating highs and lows, history shows, are the common pattern of human hopes (Fig. 3). What role, however, has hope (or any other emotion) in normal science? Science and Conscience Is and Ought
Science-as-an-institution is value-free. It is about Is: carbon is combustible in oxygen. Science-in-the-making, however, is a bout with Ought: one ought to behave as Lavoisier did (in the laboratory) to discover what combustion is. And one does behave as Lavoisier did because combustion is what it is. Science's ethic is a necessary ethic (19) As Polanyi has put it, Science is a system of beliefs (in facts and fact-yielding procedures (the laboratory tradition)) to which we are committed. Science must claim that Certain emotions are right (20) Yet, suggests Maxwell, the student of science (for whom texts are written) tends to be cut off from every noble feeling (even hope) so long as he lives (in the classroom) in intellectual fellowship with men (and women) who may have devoted their lives to the discovery of truth (21). In our anti-historical preoccupation with presenting the recent ends of science a t the expense of an account of the means to those ends, we present lifeless, soon-obsolete views of science. Science made Is less enduring Than science being made. Science is more a process than a product. Prerequisites History for Whom When?
Some people are naturally process-oriented, others product-oriented. Mv own interest in the history of chemistry developed, not atSpicall~,slowly,aftergraduareschool, in thr middle Fifties u,hilr teaching a course in chemistry for ports and, soon thereafter, whilesearching for antecedents to a seemingly simple, useful, yet to most chemists a t the time, implausible model of molecular structure. I t requires a personal history to appreciate history personally.
T h e relevance of history (and other things) is a function of one's age, knowledge, aspirations, commitments, experience, and imagination. For those who have the necessary knowledge, writes N. R. Campbell, i t is exciting to trace the development of a great scientific theory (13). The history of the development of ideas is of all subjects, says Maxwell, that in which we as thinking persons take the deepest interest (21 ). The vast majority (of people, students, and scientists) do not, however, possess the freedom from material cares (grade-grubbing and puhlish-or-perish pressures), adds Campbell, necessary for the full development of their higher interests. Disadvantages An historically informed treatment of chemistry suffers from the fact that it is Disconcerting, unsettling, subversive. It endangers stereotypes, illusions, myths. Time-consuming. The scientist-teacher must be, also, a scholar. Lacking in easy-to-grade,non-trivial,yet not-too-difficult-to-answer exercises. ThusWanting in immediacy. Certified behavioral objectives express poorly its gentle, long-term effects. HenceIrrelevant to most students' basic safety and security need: a Good Grade. If You Can't Grade It Forget It "Anything not graded Is passed over." Concluding Comments A sense of history is a gentle, persistent force. It is like a liberal education, or a slow-acting fertilizer. Its influence, slight in any instant, may he determinative in the long run. A sense of history may serve, additionally, as a security blanket. Formal science is frequently hard, demanding, austere, remote, and awesome. It can he reassuring to trace its development, step by step, from simple, humble beginnings. A sense of history can do service in several senses (22).
History Offers Insight into the present. Tests of one's grasp of a subject. Guarantees against illogical and incorrect treatments. Guards against inflated knowledge-claims of other disciplines. A change of pace from the dehumanizing rhetoric of rationalintelligenee. Illustrative examples of: People to emulate Creative reasoning
he-psycholog; of invention The divinity of simple things Limits of science, and scientists The fallacy of the crucial experiment Over-optimism, undue conservatism,blind alleys The slow, crooked character of scientific progress The role of Controversy, Chance, Commitment, Indigenous Concepts In general: Nothing far most students. Something for some teachers. Much for many authors. Literature Cited Ill Henry Ford. 12) Randdl, J. H., " H w Philoeophy Une? Its Part." Columbia Univemity Presn. New York, ,aa.l ""2 .."",
131 Bent. H. A . J Call. Sei. Teoeh., VI, [I]4611976). I41 "The Oxford English Dictionary: Oxford Univemity Prors. New York. 1971. (51 Heath. T. L.. "The Thirteen Baoks of Eudid's Elements." Dover Publications. Inc.. Near York, 1956. Vol 11, p L86. 16) Arons,A.B..sndKarplus,R..Am.J P h v s . . 44.39611976):J.CHEM.EDUC..53.334
Volume 54. Number 8, August 1977 1 465
I71 Lowry, T. M.. "Historical Introdvetion to Chemistry," The Macmillan Co., Ltd., Lundon.England. 1915. 181 Brush. S. G.,"Kinetic Theory: Pergsmon Press. New Yurk. 1965. Val. 1, pp. M. 191 Nemermv, H., "Reflections on Poetry and Poetics? Rutgers University P~ess,New Brunrwiek,NewJ~r~ey. 1972.p. 25. , 1972. I101 Blackmore. J. T., "Emst Mach." University of California P ~ e s sBerkeley, 111) Bent,H.A.. J C o l l Sci. Teach.. 1. 121,2011971). 1121 Privateeommunicstion,Dr. Forrest C. Henfr.Jr. (121 Camphell, N. R.."Whal Is Science: Dover Publications, Inc.. New York. 1953. 1141 Maser, R.F., "Developing AttitudeToward Learning."Fearon Publishers, Palo Alto,
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IaEs
1151 Rsvetz J. R., "Scientific Knmledge and Its Soeisl Pmblems: New YDI~,1971.
466 1 Journal of Chemical Education
Oxford Uniwraay P m s ,
ilfil Polya, G,"Mathematical Discovery:
John Wiley and Sons, New York. 1965. Vol. 11.
p. 182.
117) Dirae,P. A. M . h c Roy. Soc. (Lond.1, A123.714 (19291. (181 Farsday, M.. in"The Royal Institution LibraryofSeience: PhyricdSciencen:Elaeviar PuhlinhingCo..Ltd.. Barking,Esner.England. 1970.Vol.l. p. 239. (191 Bent, H.A.,Chrmistry, 48, [61,2(1975). 1201 Palanyi, M.,"Pernonal Knowledge." University of Chiesgo Press. Chicago, 1968. 1211 Niven. W. D. (Editor). "The Scientific Papers ofJames Clerk Maxwell? Dover Publications lne.. New Yolk. 196SVol. 2, p. 251. 122) Bent. H. A.. "Usen of the Past," i n "Teaching the History of Chemistry: (Editor: Kauffman. G. B.1 Akademiai Kiad6. Budapest. Hungary. 1971. Ch. 15.
