LETTERS The Next Time.. .I Hope..
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To the Editor: End of term reviews can be a bore or a real review depending upon the approach t o the subject that the instructor uses for the purpose of reviving the thought processes, supplying clue words, andlor providing other stimuli to the minds of students. Wondering about a n end-of-term review day and bow to bring the topics of discussion tozether effectively on the last dsy'and al& about a way to sns~~oodt,ye (other ihan the final exam itself), 1 recently hit on the idea of the phrase, "The next time.. .Z hope.. . ."It goes like this: "The next time you go ice skating I hope you think of the phase diagram for water and why a change in pressure (AP) allows the skate to glide easily across frozen ice. Also please remember this same phenomena the next time you drive a car on an icy road." The idea was well received and made the day a big success. The sentence has two parts. T h e first part is a reference to an everyday experience common to the student's realm of awareness. The second part of the sentence is an application of a chemical principle discussed in class (usually in great detail) during the course of the academic term. Instructors can write their own examples. Most examples will mean more to members of the class than to "outsiders" because of the experience factor of the being privy to the classroom presentation and explanation. Any textbook can be used, and the examples are probably limited only by the creativity of the instructor. The examples need not be exquisitely detailed because i t is also hoped that the example triggers a quick recall of details in the minds of the listeners. The following example demonstrates the "in-house" nature that manv examples will have: "The next time vou observe a cigaretteimoke;l hope you think about equilibrium andK,, = 210." For a different audience, this statement can be rewritten as: "The next time you observe a cigarette smoker, or light up your own smoke, Zhope you recall the equilibrium constant (K.,! for the reaction of oxyhemoglobin plus carbon monox~deto yield carboxyhemoglobin plus oxygen is equal to 210; i.e., the equilibrium of the reaction lies far to the products side of the equation." The followine e x a m ~ l e swere adaoted to chanters 9 through 14 of t i e secoAd edition of t i e general chkmistry text authored bv Brown and LeMav and are listed toeive the reader an idea of the virtually limitless number of the examples that can be used.
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The next time vou .. eo hack~ackine .. I hooe . vau . think about the prepnmricm ot'freeas-driedf i m d and how Stanford University sucredully sdva~edtheir water damaged l,ouks. The nert time you drive into a terribly polluted city or valley I hope you think about a ll-step mechanism far the atmospheric production of PANS, carbon monoxide, NOz and NO, aldehydes, and free radicals. Thcnexr time yruseea purple dilinfevtiun lamp ina hospitalorn prcturr of the supersonic Concord airplane I hope you rhink ahour the ozone cycle. The next time you hear about fluoridatingthe city water supply I hope you think of an equilibrium constant, hardness of water, and the solubility of calcium fluoride. The nert time you are enticed by a fetching perfume, or want to be fetched by an enticing perfurnelhope you think of Graharn'slaw. The next ttme you put air into a tire I hope you think about the ideal gas law.
558
Journal of Chemical Education
The next time you see a hose burst by the action of freezing water I hope you think about hydrogen bonds and the structure of ice. The next time you take a bath and reach for the radio1 hope you think of solvolysis, electrolytic solutions, and net ionic equations. The next time you put sugar in your ice tealhope you thinkabout solubility of substances in aqueous solution and the formation of hydrogen bonds. The nexr ttme you watch bicarhmatefizz hy thenetion of vinegar Illope you think of net ionic equatiunsand the reaction for any acid on uyv curbunate ur hicarbonate. Thr nexr tlme you set. or hear of a pnrirnt on a dialysis machine, or y m put anlt on the sidewalk to melt ire and snow, or8et.a gigantic Sequoia tree I hope you think about such rolligative properries ad osmosis and changing of freezing point of water. The next time you melt ice or coal steam, or watch water boil in the process of making a cup of coffee, I hope you think about the heat of vaporization, the heat of fusion, and the specific heat of water for all three phases coupled together in a phase diagram. The next time you put food in the refrigerator to keep it from spoiling I hope you think about activation energy and the rate of a chemical reaction as dependent upon temperature. The nert time you see a firefly flash I hope you think about activation energies and how the rate of that flash depends upon the temperature of the fly. The next time you deal with the catalytic converter muffler on your automobile1hope you think about activation energies and how a catalyst effectschemical reactions. The next time you use a blue dot flash bulb I hope you think about equilibrium, LeChtttelier's principle, and the cobalt reaction. Ralph Barnhard University of Oregon Eugene. OR 97403
The New Format for the Periodic Table of Elements: Concerns of a Hlgh School Chemistry Teacher To the Editor In order to avoid the confusion caused by the changein the use of the letters A and B to designate subgroups of elements in the periodic table of elements, the ACS Committee on Nomenclature has recommended a new format [1984, 61, 1361. This new recommendation is arbitrary. I can't recognize any improvement over the equally arbitrary existing designation of A and B subgroups. This new format will add to the confusion of the high school students. Notations like l l d and 12d will give the impression of more than 10 electrons in sublevel d and also will indicate subleveld belonging to principal energy levelslike 11and 12. For example, in the configuration 4d2, the number 4 represents the number of the principal energy level. Students will infer that l l d and 12d indicate the existence of principal energy levels 11and 12. The numbers 1to 18 will aiso add to the confusion of teaching valence electrons to the beginning students in high school. The notation 3f for lanthanides and actinides is also confusing. Students will interpret this to indicate the existence of sublevel f i n principal energy level "
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If we must have a change, then I suggest we use Roman numerals I through XVIII. Replace the letter d for groups 3d to 12d with the words "d block elements" written over groups 111to XII. In addition, delete the number 3 from the f block elements. I t is also auite useful to retain the period numbers for horizontal rows of elements. I would prefer the format used by Edwards and Sienko, 1983, 60, 691, or that of Araneo, 1980, 57, 784 with some minor modifications. C. V. Krishnan East islip High School Redmen Street Islip Tenace. NY 11752
