Cosmochemistry A Topic for the Liberal Arts Chemistry Course John E. Douglas Eastern Washington University, Cheney, WA 99004 The content of the liberal arts "Chemistrv and Societv" courses is a matter of continuing discussion among chemists ( I ) . Although there are many approaches to such a course, the following components are usually included.
t h e transformation of energy and matter duringthe first few minutes star formation and nucleasynthesis
Reading List The General Outline Chemical principles-basic Chemistry in historical perspective The history of science The scientific method Our scientific heritage Chemistry in contemporary perspective Consumer chemistry Environmental and resource problems Health and drugs
The following book and four journal articles gives a partial suggested reading list for the topic.
Adding Universality as a New Perspective This article suggests the inclusion of another perspwtive, that of chemistry elsewhere in space and time, which can be called "casmochemistry". This topic broadens the students' outlook on the universe while reinforcine basic chemical principles. I t gives a n interesting application based on current research developments. I n this unit I develop two broad themes. One is the universalitv of chemistm throuehout ., mace and time: The same elements arc found everywhere in the universe, and the ~ r i n c i p l rofchemical .~ svnthesis are also universal. The second theme is the origin bf the chemical substances that we find around us today, both living and nonliving. The major concepts that develop these themes are described below. alone with readine lists that offer some helpful sourcek of in?ormation. opef full^, these ideas will encourage others to develop such a unit for their courses.
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The "Big Bang", Stellar Evolution, and Nucleosynthesis The sequence of events leading to the formation of the chemical elements throughout the universe is described. Important concepts include evidence for the "higbang", that is, the red shift and the discovery of residual microwave radiation
Weinbergs book The First Three Minutes gives a gwd review of the initial events (2). *Viola's recent paper in this Journal (3)covers nucleosynthesis. Atwood's recent paper in this Journal ( 4 )discusses he supernova of 1987, which dramatically demonstratedthat nucleosynthesis is a continuing process even today. Horgan reports from a recent Nobel sympo&m on "thebirth and early evolution of our universe" (5). 'A recent review by Flam describes current controversies among eosmologis~over the way in which structures in the universe were formed from the initial homogeneous distribution of energy and mass (6).
Chemical Synthesis in Space The theme of this discussion is that chemical synthesis is a ubiquitous process that naturally occurs everywhere in the universe, not uniquely on the earth. Evidence for the existence of extraterrestrial molecules is cited, including infrared absorption spectra of interstellar space the chemical composition of meteorites and comets
Reading List The following four articles from four different journals are recommended. Irvine surveys interstellar molecules (7). Kunzie diseuses both interstellar molecules and those found in comets (8). Berry describes the chemical composition of Halley's comet (9). Chyba et al. discuss possible delivery of organic material to the earth by comets (10).
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Chemical Synthesis on Earth and the Origin of Life The composition of the primitive earth and its atmosphere are described, followed by subsequent changes. Significant points include the processes of mineralization the large greenhouse effect on the early earth (This was associated with an atmosphere rich in carbon dioxide that may have saved the earth from becoming a cold and lifeless planet.) the origin of molecular oxygen from photosynthesis the formation of organic molecules that eventually became self-reproducing,that is, life Important ideas relating to the origin of life are included. classic laboratory syntheses of organic precursors to the comdex molecules of life from sim~le inorganic eases the ;ole of lightning and deep sea vents as sources of energy the catalytic function of clays and RNA
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Reading List ' A provocative new viewpoint cnn bc introduced by mcnrion-
ing Schwabe's*genom!upotential" hypothew ,111. rl'mtcin synthesis is driven bv "chemicnl determinism".The symbal f& the process is not the evolutionary tree but a ehaotic attractor.) Useful reviews include those of Ferris (12),Horgan (131, and MacDonald (14). Scattergood, Marais, and Jahnke (15) and Schwabe (11) summarize the events that may have caused the transition from nonliving to living matter.
Chemistry on Other Planets The chemical composition of the other planets are reviewed, emphasizing the differences between the inner, dense rocky planets and the outer planets, which are composed of frozen gases. It is useful to wmpare the climates
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on Mars and Venus and relate these to the greenhouse effect. This provides a perspective for the greenhouse effect on the earth, both past and present.
Reading List
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Beattv and Chaikin (16)and Suess 117) ~rovideuseful sum. manes of the chcmiatry ofobjwts in the solar system. Kasting er nl. 118 and Hurunitr (19) discus climatic implications for the earth and other planets. ~
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Summary This paper has presented suggestions for topics in the liberal arts chemistry wurse that will broaden students' perspectives on chemistry and the surrounding physical universe. Some useful sources of information are provided because these topics are not covered in the most commonlv used textbooks. Readers will want to further develop topi& of particular interest and seekout additional sources of infokation in their own library. Literature Cited 1. Hill, J. W. J. Chem Edue. 1986,62,765761.
2. Weinberg, S. The First ThmeMinutes:Basie B o o k N e w York. 1988 3. Kola, V.E. J Chem Educ 1890.67.723-730. 4. Atwmd, C.H. J. Chem. Educ 1980.67.731-735,
Horgan, J.Sci. Am. 1990,263141,108-117. Fhm, F. S c i e w 1891,254,11061108. Imine, W.M. ThePlo~toryRepon1987.7(61.6-9. Kunziz. R. D i f f o u ~ 1988.9131.69-76. r 9. Berry, R.AsCmmmy 1987,15(bi7-22. 10. Chyba, F C.; Thomas, P J.; Bmobhaw, L; Ssgan, C. S & m 11. Schwabe, C. Compulprs Moth.Applk. 1890,20,281301. 12. Ferris. J. P. The Phmtorv Remrf 1981. 7(6).10-11. 5. 6. 7. 8.
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