Periodic law (Curry,E.; Chandler, J.; Mackay, L.) - ACS Publications

Two reviews of a software program which serves as a data base for 20 items of information on the first 103 elements. Keywords (Audience):. High School...
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Summary. At $250 ($500far nonacademic users) MGP will likely seem a bit expensive to many, considering some of its limitations. Furthermore, the program lacks a mechanism for dumping the image to a printer. To this reviewer, MGP's greatest attraction is as a teaching tool. It is easy enough to master, and richenough in features that it could he used by most students to discover details of molecular structure that would he very difficult to see, even with molecular models. I t prohahly would not he my first choice for serious research because of the lack of geometry optimization and the amount of hand work needed to prepare the data file hefore invoking some of the program's most useful features. John J. Houser The University of Akron Akron, OH 44325

Periodlc Law E. C u m J. Chandler, and L. MacKay. Educational Materials and Equipment Co., Old Mill Plain Road. P.O. Box 2805. Danbuly. CT 06813 Hardware: Apple II family. Also available for IBM PC. Components: 2 disks, Teacher's Guide, Student Workbook Level and Sublect: High school or college general chemistry Cost: $69 ($76 for IBM PC)

Revlew I Periodic Law was class tested by a group of 20 first-year chemistry students, most of whom plan to major in biology, chemistry, or pre-medicine. The CAI was scheduled during a laboratory period so that up to two hours could he devoted to the exercise. Each computer was shared by a group of two or three persons. This tended to stimulate discussion and further experimentation; indeed, most students stayed beyond the allotted time. My students enjoyed using Periodic Law. The classroom mood was cheerful. The software generated enough interest that most people ran more trials than the required number for grade credit. Everyone agreed that the program helped them to understand chemical principles hetter. No one complained of undue difficulty in getting the computer to do what it was supposed to do. That was a real tribute to the package's user friendliness, since this particular class had not heen assigned any prior work on microcomputers, and indeed most class members had not used Apple computers hefore. The heart of Periodic Law is a data base which contains up to 20 items of information on each of the first 103 elements. Users can obtain this data in one of three formats. First, one can look up the pwpertie~of any desired element and display them in table format. This routine is simple but versatile. The choice of element may be specified by atomic number, by rhem~calsgmbul,

or by name (or recognizable fragment there-

00.For example, data on carbon was elicit-

ed by the entries "12", "C", "Carbon", "Carbo", "Carb", and "Car" (but not, of course, by "Ca"). There is room in the table to display properties of two elements side hy side for comparison. Each element can be changed independently. Second, and, in my opinion, the most usefulformat in the package, one can select one of 13 quantitative properties and graph that property as afunction of atomic number for all 103 elements. All but one orooertv (atomic mass) illustrate the oeridie lnw. cursor can bemanipulated over thegraph to identify the elements. The monitor displays the chemical symbol, atomic number, electron configuration, and numerical value of the chosen property for whatever element is indicated hy the cursor. Using this device one can discover, for example, that on a graph of first ionization energies the maxima belong to nohle gases and that the minima belong to alkali metals. Another way to use the graph routine is to plot data for just one group or one period of elements, thus permitting a more detailed study of periodic trends. Third, one can use a SEARCH AND SORT routine to identify all elements that match up to three nser-specified criteria. If an element meets all the criteria, its symbol is displayed bn a facsimile of the periodic table. This can provide a striking demonstration of how the table groups similar elements together! A search for the "largest atoms" reveals that elements whose atomic radii exceed 2.0 Angstroms are located a t the extreme left (alkali metals) and the extreme right (the noble gas radon). A search for "reactive metals" (electronegativity 1.0 or lower) identifies the elements in columns 1 and 2. A search for high melting solids shows that the elements with melting points greater than 2000' C are boron, carbon, and a compact cluster of 10 outer transition metals. The SEARCH AND SORT display includes a cursor that highlights one element at a time, and causes the numerical properties of that element to he listed. There is also an option to print or display a list of the elements and their properties. The list is supposed to be ranked in ascending order of the first property specified in the search. However, that feature did not alwavs work correctly. Periodic Law places an extensive data base at your fingertips and lets you use the data in several creative ways. Unfortunately, the software does suffer from some technical flaws. As mentioned earlier, there seems to be an error in the algorithm used to rank elements in ascending order during SEARCH AND ~

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SORT, because some of the entries appear in wrong places. For example, I prepared a list of the elements in ascending atomic mass order. (This is a convenient way to identify those elements that resisted Mendeleev's efforts to fit them into an atomicmass-order periodic table, or which would have given him trouble, had he known of their existence.) Inexplicably, technetium (mass 98) and promethium (mass 145) showed up as the last two elements on the list! I found many other examples of misranked elements while testing this program. The most ohvious shortcoming of Periodic Law is that, at least on an Apple IIe, its execution is extremely slow. Every student who tried the program commented on the amount of time required togenerate agraph (over 3 min) or to do a SEARCH AND SORT with periodic tahle display (nearly 4 mid. The graphing routine seems to take even longer than it does, because during the first half minute the screen is completely static and you see only a "please wait . . ." message. SEARCH AND SORT is actually more time-consuming, but at least there is always something to watch: the atomic numbers and elemental properties flash briefly on the screen as the search proceeds, and symbols are added to the periodic tahle as soon as elements are found that meet the selection criteria. A second annoying shortcoming is the poor quality of the graph display. Several students commented on the small size of the graph; it uses less than 113 of the screen area. While I understand that this was done to leave room far simultaneous display of two graphs, I still wish there were a way to display a single, hetter detailed plot that utilizes the full screen. The arrow-shaped cursor used to identify each element also drew criticism. This arrow can he very difficult to see, especially on a graph that displays all 103 elements. One problem is that the arrow gets very close to the plot, sometimes obscuring the line itself, at other times obliterates the horizontal axis and its lahel. Another problem is that the arrow is wider than necessary and it is not exactly centered on the X-coordinate it is supposed to he locating. As a result, it is hard to see whether you have in fact reached the maxim- (or minimum) point on the plot; sometimes one has to relv on the readout of numerical valUPP whirh, unforrunatclg, is displayed onlv one element at a lime. Still another annoyance is the set of vertical d a a h d lines that correspond to noble-gar atomic numbers end thus divide the graph into sewn periods. I wished I could have suppressed the lines for two reasons: (1) they the graph ~~

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Summary Ratlngs: Revlever category Ease of Use: Subject Matter Content: Pedagogic Value: Student Reaction:

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a cluttered appearance; and (2) more importantly, they denied the student the opportunity to discover the periods for himself. After all, Mendeleev noted the periodicity FIRST and inferred the existence of periods SECOND, not vice versa. I think students should be allowed to re-enact Mendeleev's discoverv. , The graph n d n e allows you to save one graph while you generate a second one. This is useful since several of the properties are interrelated. For example, elements that are maxima on the melting point graph also tend to be maxima on graphs of boiling point, heat of fusion, and heat of vaporization. The dual-eranh feature demonstrates this very rlearly. Vnfortunately, vou rannot ~peciiywhirh of the two graphs should he kept for future reference; only the most recent one is saved. This is all the more ineonvenient in view of the time required to generate the graphs. Ipersonally would prefer the graph procedure could he more versatile. For one thing, I would like it to offer the option of using the full vertical dimension of the screen to make more detailed graphs. More importantly, I would like to be able to choose an X variable from the same menu offered for the Y variable, instead of being limited to atomic number as the X variable. The extra flexibility would greatly enhance the teaching potential of the program. For example, one could study periodicity of elemental properties vs. atomic mass (as did Newlands, Mendeleev end Meyer). One could see the obvious deviations from periodicity at T e n and ColNi (which were noted by Mendeleev) and at five other pairs of elements (unknown t o Mendeleev). One could also graphically explore relationships between two elemental properties. For example, what is the mathematical relationship hetween melting point and hest offusion? Between boiling point and heat of vaporization? Between electron affinity and ionizat i o n energy, a t o m i c r a d i u s , o r electronegativity? Furthermore, I wish it were possible to add more parameters to the data base. Three elemental properties I'd like to include are density, specific heat, and frequency of X-ray emission. The first of these oscillates in an interesting periodic fashion. The latter two do not oscillate, but they do vary systematically as functions of atomic mass or numher, and one could easily use the Periodic Law software to demonstrate the Dulongil'etit relationship and (above all) rav. fre~. Moselev's ~,atomic number-X quency relationship After all, Mosrlry's discovery is the hasis for the periodic tahle as we knou,fi today. A final di~appuintmenrwas that Peric,dlr I.aa makes relauvcly little use of the cohr graphics capabilitiesof the microcomputer. 1 can think of at least two ways to improve the nroeram bv, exnloitine color: first. when .. . drawing graphs of an ~ l ~ m e n tpmpeny al vs. atomic number, rhange the rolor of the line at theandi>feachperrod;serond, whenplutting search results on the periodic table, assign a color to the elemental symbol depending on the magnitude of a selected property, thereby displaying a spectrum. ~

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In summary, I would rate Periodic Low as a powerful and effective teaching tool, well suited either for lecture-demonstration use (with 8 large-screen projection device) or for handa-on laboratory exercises. I t has an extensive data base, and it can display the data in several useful formats. However, the software could have been improved had it been given more thorough testing and revision before its release by EME. I t contains loeic " errors that need to be corrected.. and it could stand some imorovemcnt in the srrar of speed. graphic> design and versatility. Furthermore. it really ought to provide a way to add new categories of data, as well as to enter the properties of recently discovered elements when that data becomes available. Unfortunately, given the security measures taken on commercial releases, there is little or nothine- a .nurchaser can do to improve the program. I arncerelv hope that EMF will update their software and issue a new relesse in the very near future. Joseph H. Lechner Mount Vernon Nazarene College Mount Vernon. OH 43050 ~

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Ease of Use This is a very user-friendly program. I t is self booting and clearly self explanatory. The directions may be followed by any user who has worked at all with other programs even without reference to the help sections. The program itself is relatively speedy except when a long list of properties for an extended ranee of atomic numbers is requested. The program will explain that it is searching or plotting.

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Features and Intent This program is essentially an extensive data base containing available values for 18 properties of the elements of the periodic table, atomicnumbers 1-103. I t offers three different pathways for displaying and comparing selected properties. In the first section, a table display is available that lists the chosen properties (up to 10) in the middle of the screen and the a d u al values for twoelements a t a timeon either side of the chart. The second section presents the graph of any chosen property against a selected range of atomic numbers. The numerical value of the graphed property of any element may be requested and resented on screen via movement of a pointer on the plotted praphcurw. A senmd graph of another set of relationships ran he placed beneath the first graph on the screen. These graphs may be printed. The third section will find all the elements that exhibit selected property ranges within up to three different properties. The computer will place on a blank periodic table all the elements fitting the selected eriteria. The actual values for each element can then be read, one element at a time, beneath the periodic table. One can also request ail values in a displayed ordered list, whichmay be printed. This program is not aimed a t any particular level, and is quite useful for any student or teacher workine with the neriodie table. It preiencs a variety of ways to examine trends,and the w#rkbookarcompan) iny the prugram allows a springboard for students to view the whole program, from which hopefully they would pursue furtherinformation an their own initiative. The program does requires prior definition and introduction to the properties to be investigated.

Subject Matter Content This program contains a comprehensive listing of properties of the elements, well chosen to suit most needs, but they are not introduced. I do feel that the properties which are contained in the data base might suitably be defined initially in the program itself rather than just in the Teacher's Guide. I do object to the definition of "first ionic radius" as found in the Teacher's Guide. This property is first described as "the radius of the most readily formed ion of the element". This is followed by the statement "corresponds to the first oxidation state listed in the data base". The data base, however, lists oxidation states in order from most to least commonly encountered. This effectively equates "easiest formed ion" with "most common oxidation state," and leads to the disquieting presentation of P+5 as the most readily formed ion of phosphorus and Mnt7 the easiest formed ion of manganese when one calls up the first ionic radius of these elements. Inasmuch as the Teacher's Guide is often used as e definition source, I think that a redefinition there is certainly in order. Ideally, a separate programming for first and second ionic radius, divorced from common oxidation states and reflecting the easiest "true ions" formed, would be most appropriate. I also feel that including the +1 state of beryllium, as well as the -2 and -1 state of nitrogen, and not including the t 1 state of chlorine or the -3 state of phosphorus in the data base of common oxidation numbers is very much at variance with the majority of tables of common oxidation states. Pedagogic Value At MCC we do not have an Apple computer lab routinely available for an entire class, but we do have available a numher of Apple 11's for classroom use and a relatively inexpensive Kodak DATASHOW interfacing apparatus that allows the monitor screen of the computer to be projeded via an overhead nroiector onto the large . "~ overhead screen. I utilized this setup to do my entrre lecture on periodic table property trends via the Periodic Law program, and the rcwlti were quite good. A handout packet for the students, which included a page of definitions, data sheets, pre-ordered graphs, and report sheets, was distributed and discussed a t the beginning of the period. The table display portion of the program was utilized to present electronic configuration, common oxidation numbers, covalent radius, first ionization energy, electron affinity and electronegativity values for two elements at a time. Data was gathered and trends were noted as each new set of data appeared upon the screen for several periods and groups of elements.

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Using the second part of the program, various properties were graphed onscreen against the atomic numbers of elements of several periods of a group, reinforcing the trends noted in part one. Using the third portion of the program, covalent radius was related to first ionic radius, with the elements being studied shown in their position on an otherwise blank periodic table. This provided a timely change in the visual presentation. Finally, the students were directed on their report sheet to graph properties versus atomic number using the data they had gathered and to draw conclusions about the trends they had observed. They were asked to relate all of the property trends to effective nuclear charge and metallic and nonmetallic nature, eonceptsdiscussed before class hut not presented or mentioned in the program itself. All this turned out to he a very successful wedding of "high tech" and experimental learning, and in the process I was able to present far more actual data in some sort of reasonable order while utilizing the same classtime as in past lectures. Student Reaction The students were asked to complete their report sheet with an evaluation of the program in comparison to a "conventional" ledare on the topic. In the two sections of about 20 students each, only three students were unenthusiatic, disliking all the data gathering. The vast majority felt that hy the time they had seen the data, graphed it, and rediscovered the trends for themselves they had learned a lot more than they would have learned from a usual lecture, and they appreciated the novelty of the non-routine approach, even with the extra work involved. Summary Tnis program provides for the instructor a u,ealth 01' data from which to huild an excellent classroom presentation, complete with three modes of display. The Kodak Datashow or other eomputer-overhead interfacing devices bring computer programs to the classroom even if a computer per student is not available, and I am discovering that this is a quantum leap forward in the teaching of chemistry. The use of the program by individual students would work well in a computer lab situation if available. Sharon L. Gardlund Mscomb Community College 14500 Twelve Mile Road Warren. MI 48090

Chemlstry: A Flrst Course G. Rayner-Canham and A. Last. AddisonWelsey: Don Mills, Ontario, 1988. xiii 594 pp. Figs. and tables. 20.8 X 24.2 cm. $24.95 Can.

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As stated in the Preface. this textbook is aimedat the introductory high school ehemistry student. Assuch, it providesa rlpar but rigorous description of chemistry. Indeed, its rigor is apparent, with very little watering down of the subject. Indicative of this is the attitude taken with example prohlems throughout the text: dimensional analysis is

pushed almost exclusively as a problem solving method, and the answers are demonstrated in detail and a t length. At the end of each chapter is a long list of questions and nrohlems to test the readers' comnrehension. Some instructors may think the authurs'attitude roo rigorous ior beginning rtudents; others (myself included) will welcome this perspective. I t was easily noticed thatthe authors tried to point out meaningful connections hetween textbook chemistry and the world around us. Acid rain and nuclear accidents are orominentlv discussed. and illustrations point out how various chemrcals are used in everyday living. Scattered through the chapters are "Fearure.," short essays expounding on particular people or subjects related to the textual material. These features are sure to invoke interest. The text and prohlems make exclusive use of metric units, eschewing common units as atmosoheres and Molaritv (using kilopascals and'mo1es.l- in stead)..^" lac;; the hook does not even mentivn molalitr. or normality as concentration units; dimensional analysis, again, is used to solve prohlems that usually use these units. The book bas refreshing sides to it. I n the discussion of the scientific method, the authors point out that not all great discoveries and advances arise from strict adherence to the scwnufic method, they rite thediscover. be- of Teflon and nohle gas compwnda as examples. Such admissions are rare in firstyear textbooks and promote the idea of seientists as human beings. Color plates show many elements in their elemental forms, as well as productions of aluminum from hauxite and oetroleum oroducts from oil sands: the illustrations in general are aptly chosen. The fact that the text isobviously Canadtan may be considered a drawback by potential non-canadian instructors. Surely the principles are the same regardless of nationality, but some of the references may not evoke the same level of comprehension in non-Canadian students. There is even a welcome chapter on industrial chemistry near the end of the book-titled "Canadian Industrial Chemistry"! Why "Canadian"? Why not just "Industrial Chemistry"? I wish the authors had included certain topics that are surely worth studying even by high school students: solution properties (like freezing noint de~ressionsand boiling noint eleva&s). hvdioeen hondine. some ;hermodynamicsithete~hasnone&h the exception of the definitions of enthalps. exothermic, and endothermicl, and should even have some mention of plastics and polymers and their almost universal uses. Still, this hook would he an excellent aid for learning the basic fundamentals of chemistry. Davld W. Ball Rice Univsrsily Houston. TX 77001

Physlcal Organlc Chemlstry NeilS. isaacs. Wiley: New York. NY. 1987. xviii 828 pp. Figs. and tables. 24.4 X 15.4 cm. 549.95.

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At the beginning of his foreword to this hook, Neil Isaacs defines physical organic Volume 65

chemistry as "the study of the underlying principles and rationale of organic reactions.. ." It is thus in the line of earlier works of the same title by Hammett, Hine, Kosower and others, and in a certain contrast to the Advanced Organic Chemistry texts of Wheland. Fuson. Fieser and Fieser and March. The latter emphasize advanced material: the former, an advanced way of lookmg at the marerial runsidered. Thm edwnced way is thnrugh molecular orhrral theory, and lvaacs does a fine job of introducing it and applying it to specific cases. As a compendium, his work is admirable; it covers the literature up to 1986. The first nine chaoters deal with the"underlvine prmciplea,"and the~jtherseven with specif~c reaction types. One surprising feature is the grouping together of all substitution reactions at carbon in chapter 10: nucleophilic and electrophilic at saturated, aromatic, and carhonyl centers. The work falters, it seems to me, as a textbook. This is a British book marketed in the United States, apparently without change, by Wiley. British textbooks have always been much too terse for most American tastes. They tend to lay out the essentials without exposition or explanation, placing a heavy burden on the hackground of the student or the presentation of the professor. This work is certainly in that tradition. As a textbook, though it may cover more material, it cannot compare with Lowry and Richardson's Mechanism ond Theory in Organic Chemistry. The British source of this book affords other problems. I t t w k m e a while to realize that "rlpm" did not mean radius per picometer, but rather radius in picameters. The book should have been edited for American readers. Besides, the editing that was done seems to have heen for the convenience of the typesetters, not for the readers; thus, the reference an p 416 to the tahle on p 392, and the displacement of the tahle on p 697. This is not to deny that this is a most valuable source hook that should be in every college library and on the shelves of most teachers of organic chemistry. Issacs has done a most thorough job of summarizing the literature of this important field. Charles J. Thoman Stephen F. Austin State Unlverslty NaCOgdOCheS, n: 75962 ~

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Physlcal Chemletry, Thlrd Edition Ira N. Levine. McGraw-Hill: New York, NY, 1988. xvii 920 pp. Figs. 21 X 24.2 cm.

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According to the author, "the textbook is written for the standard undergraduate course in physical chemistry." Since there are several such so-called "standard undergraduate courses," this reviewer will comment on the individual chapters as they would he used in the average standard undergraduate physical chemistry course. On comparison with the ever popular textbook hy P. W. Atkins, this textbook fares very well. Both Atkins and Levine have tried to (Continued on pnge A336) Number 12

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