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063 me Ambit of Chemistry Almost every genernl chemistry text in common use pre-

ients a (lrfinition of chemistry that is vacuous. The typical definition of chemistry ns "the science that deals with the cwnposition, structure, and properties of substances and of the transformatinnsof matter." was, in fact,endorsed hy the ACS Council at it recent national meeting ( 1 ) . Although this definition may 11r w~~rknl~lf: in political contexts, it is iar less so in academic contexts for the fidh,wing four reasons.

11) To say that " c h r m i s t ~ is the sturly of the rompmition and transformations of matter" dws not distingyish chemistry from other sciences (scf: the tahlr). All natural iciencei, past and present, have entailed thr study o f the cornpoiition and transformation of matter. As thr tithle indicates, hiuloky is the study of the composition of matter (cells) and its transfor- mation by meiosis or mitosis, and an analogous claim can be made for physics.

(2) Statements about "chemistry" in the popular press are not rendered as meanineful to students as they might be. . - Recent articles have claimed that "98% of all energy comes from chemical sources," and that "a gene has been chemically synthesized." The first statement was meant to distinguish fossil fuel (a chemical source) from nuclear fuel, solar heat collectors. and hvdroelectric sources: the second was meant ~~ ~~~-~~ " to differentiate a preparation invol;ing intentional control of bond formation and destruction from one in which condi- tions are merely made right for natural replication. Neither statement carries the intended meaning if the standard textbook definition of chemistry is assumed.

(3) Failure in applications external to the text employing the definition is not the only drawback. Logical lacunas appear immediatelv-Why is the boiling of water frequently pre- sented as thr paradigm p h y s ~ ~ a l ch3nge [that is. prriumihly, one tu l ~ e studii.d hy phyaiciits) wen though it fits the drfi- nition ot'chcrnistrv and. in fact. is usuallv discussed in detail in later chapters ofthe chemistry text? I t :s not surprising that distinctions between "physical change" and "chemical change," or "physical property" and "chemical property" confuse students, since all changes in matter would be rhrm~t.al changes hy theaccepted definition. One frequently reads that ch(,mirul chanaes are those that alter rhp r l~~rn i rn l identity of a substance. This statement is tautological and therefore contains no information that will help students to distinguish a chemical chanee from. for examde. a bioloeical one. biological change isone which alters the biological identity of something. Tounderstand the force of asentence of this type, a student must be told what difference is indi- cated bv the use of the different words, "hiolo~cal" and "chemi~al." Furthermore, the accepted definition does not help us escape further tautologies, such as "chemically pure substances are those that cannot be further purified by chemical chanees." Some authors go so far as to say that since chrmistry deals with composition and transformiltions of all matter, we are dealing with chemistry in everything we do, or that ever\.thinv is a "chemical." This statement ii simolv not

All Natural Sciences are Concerned with the Composltlon and Transtormations of Malter --- - - - - -

Disclpiine Compasition Transfwmatian

BIOLOGY cells meiosis mitosis

PHYSICS leptons annihilation mesons tran~m~tation baryons

CHEMISTRY atpms bond fwmation mole~~le~ bond destruction

it when we discuss the relationship of chemistry to psychology. As a consequence, we sometimes confuse the issue by using phrases like "molecular psychology" ( 2 ) and "chemistry of mind" (3). A clearer concept of the ambit of chemistry would avoid these mistakes. Proposal for Redefinitlon

Examination of the table should have hinted that the def- inition I will nrooose for ehemistrv is one understood im- . . plicitly by most writers but which has not found its way into words in the introductorv cha~ te r s of texts. Chemistry is the - . discipline that selects atoms and molecules as the funda- mental units of nature and auulies knowledge of their be- . . .. . hauiar lo explnin ptwnr,mmu. This definition does lead to a iirnifirant reorientatinn. I'henomrna [whether the boiling of watrr, the plsnningofadirt, the replication ofa ceII,theaciiun 01 hrroin, the pmhlem of water poll~ttion, or the etiology of a disease) are not intrinsically chrmical, physical, or biolw5cal. It is the mode of our understnnding that is classified. Thar is thediscinlinr. Thus thr hil ine of water and hvdroeen sulfide . .. is ph).,ical when it is studied bv measuring the vapor pres- surrs of the massive liuuids. This studv reauires no uwmic or molecular description; and we migh

revolution" as being the correct identification of chemical substances (according to the phlogiston theory, a metal oxide was simpler, that is, purer, than the metal itself for example) and not simply the point at which quantification was introduced. Quantification was used to prove the phlogiston theory: It was known that the diminution of the hulk of air hv an enclosed flame was invariablv 1/15 to 1116 of its

to distinguish chemistry. 5. We avoid chemical Chauvinism. The claim that elements

and compounds are the simplest substances ignores the fact that each discipline chooses its own simplest substance in order to understand any particular sample of matter: HeLa cells are (or once were) hio- logically pure (6 ) . Elements are complex mixtures from the point of view of nuclear physicists.

6. The term "chemical" is applied to matter to imply that something is known of its atomic or molecular constitution, and au- thors who claim that everything is a chemical are speaking very loosely. We treat chemicals in a manner dictated by our under- standing of atoms and molecules, and it is strained usage to call a fungus or even a painter's chrome yellow a chemical. Chemical Change

Buildine uDon this new definition of "chemistrv" and .. . "chemical suhstance." mmc. sense can be made of other con- ceoti: Themicnl rhanaec" are rhoae that are und~rsrood in teims of bond formation or destruction (not transformation of matter or substances). Thus where one text asserts, am- biguously, that changes in a river's composition are chemical changes, it would be better to say that we understand some in terms of chemistry (measurement of mercury levels), some in terms of biology (growth of algae), and some in terms of physics or geology (temperature, flow rate, and path). The sentences about gene synthesis and the sources of energy oreviouslv auoted are now clear and meaninaful, since it is no , . Ionyrr necessarv to resort tu the tm~tnl~~gically true land un- heloful) statement that chemical chances are those that alrer the-chemical composition of matter. - Chemical Properties

Chemical properties should be understood as those which

influence, or are understood in terms of, the formation or destruction of bonds. "Chemical orooerties" have been de- . . fined previously as those characteristics involved in the transformation of one suhstance into another. This definition does not exclude properties of nuclei which make them sus- ceptible to transmutation or thermodynamic properties which might better be classed as physical. Examples of "physical properties" that are often mentioned include color (which might he psychological, or chemical if understood by appli- cation of molecular orbital theory) and taste (which is cer- tainly psychological). Chemislry and The Mind

Finally, the new definition makes explicit the chemists' precinct in matters dealing with the brain. Thoughts cannot be considered chemical. so there can be no "molecular ~ s v - chology." I t is crude reductionism (7,8) to consider chemi& an adequate medium for discussing mind. Chemists may study the similarities in molecular geometry between LSD and natural neurotransmitters and hypothesize mechanisms of action, but the effects on consciousness are presently the psychologist's exclusive domain.

Literature Cited i l l Chem ond 8%. Nems, April 3,1978, p. 32. 12) Mahler, H. %and Moure, W. J., J. CHEM. EDUC.,IZ,19 119651. (a) MCG~W,P . ~.,amr,im a i m t i a t , 59.221 119711. 141 Soo, for anexample ofthiseonfusion, problem 2B3in Miller.F.,"CollegcPhyries:'4th

d.. Harcourt Bmce Jovsnavich. Inc , New York, 1917, p. 25. 151 Conant, J. 8.. Horuard Caw Hlatorrps inExpa,imsnfai Science. C- 2:'Tho Overthmu

oftha Phlogiston Theory? Hsrvard University Press, Cambridge, MA, 1957. 161 la) Culliton, B. J., Science. 184, LO58 ll974J. lbl Culliton. 6. J., Science, 184.1268(19741.

lc) Nelson-Rees. W. A.andF1andermeyer.R. R..Srience, 191.98119761. (7) O'Conner, J.. ed.,"Modern Msterialism: Readings on Mind-Body Identity," Hsreourt,

Brace, and World, lnc.. New York, 1969. This book contains en extensive hihliog- raphy

181 la1 Chappell, V. C.,d.,"ThePhil-phy af Mind." Plontice-Hall, Inc. EngleumdCliffs. NJ. 1962. (b) Shslfcr,J. A.,"The Philosophyof Mind: Pcentice-Hall, Inc, Englowaod aim, NJ, 1968.

Edward W. Vitz Aquinas College

Grand Rapids, MI 49506

328 1 Journal of Chemical Education