Ralph H. Petrucci and William S. Harwood. Prentice Hall: Upper Saddle River, NJ, 1997. xxvi + 989 pp. Figs. and tables. 20.6 x 26.0 cm. $85.

General Chemistry, Fifth Edition

Kenneth W. Whitten, Raymond E. Davis, and M. Larry Peck. Saunders: New York, 1996. xlv + 1051 pp. Figs. and tables. 22.2 x 26.0 cm. $85.

Modern texts of general chemistry are considerably better than they were thirty years ago, and the two books reviewed here, Petrucci and Whitten, clearly follow this trend. Both are well-written teaching instruments with lots of student-friendly features. I speak from experience, having taught out of earlier editions of both, and having heard the comments expressed by students about them. Both are used annually by tens of thousands of students. The successful formulas for writing good general chemistry texts are currently being used in at least a half dozen clonelike cousins, making adoption decisions more difficult.

Both texts succeed, for the most part, in accomplishing what they set out to do. Whitten is "intended for use in the introductory chemistry course taken by students of chemistry, biology, geology, physics, engineering, and related subjects. Although some background in high school science is assumed, no specific knowledge of topics in chemistry is presupposed" (Preface, To the Instructor, p vii).

Petrucci states that "most general chemistry students have career interests not in chemistry but in biology, medicine, engineering, and environmental and agricultural sciences as well as in many other fields. that general chemistry will be the only college chemistry course for many students and their only opportunity to learn some practical applications of chemistry. We have designed this text for the 'typical' students" (Preface, p xvii). My guess is that Petrucci would also want the text used by chemistry majors.

Mathematics levels and expectations are quite similar: a working knowledge of scientific notation, significant figures, logarithms, and the quadratic equation. Appendices in both books present calculator-based reviews. Petrucci briefly footnotes integrated solutions to rate equations for first- and second-order kinetic processes. Whitten takes a similar but broader approach to calculus within a special "Enrichment" segment of the Chemical Kinetics chapter. More mathematically inclined students will appreciate these nonintimidating inclusions.

Both books contain numerous chapter addenda. Whitten's "Enrichment" segments provide "more insight into selected topics for better prepared students." The "Chemistry is Use" boxes introduce environmental issues and practical applications of chemistry. Petrucci's counterparts are the "Are You Wondering" and "Focus On" segments. One may ask who "reads" these extras, teacher or student? In their new book, Talking About Leaving: Why Undergraduates Leave the Sciences (Westview Press), Seymour and Hewitt conclude that large, impersonal introductory classes are most responsible for student dropout. Do segments such as those noted above, regardless of how attractive they appear, actually help motivate and retain science/chemistry students, or do they simply add to the length and cost of the text?

Comparison of chapter titles reveals substantial similarity in content and its typical or accepted order of presentation. The 28 chapters in each could theoretically be presented 14 in the first semester, and 14 in the second. However, this division is arbitrary, as professors may opt to omit as many as five or so concluding chapters dealing with descriptive and organic biochemistry.

Petrucci takes a more conventional two-chapter approach, separating "Thermochemistry" in Chapter 7 from "Spontaneous Change: Entropy and Free Energy" much later in the text in Chapter 20. Whitten uses a single Chapter 15, "Chemistry Thermodynamics". Students challenged by these concepts may prefer the Petrucci approach, encountering enthalpy et al. in the first semester, and entropy/free energy in the second. In any case, it would seem better to introduce free energy before equilibrium (as does Whitten) than afterwards, as does Petrucci.

Whitten uses three chapters versus Petrucci's two for chemical bonding. The former's Chapter 9, "Molecular Orbitals in Chemical Bonding", is largely a discussion of energy level diagrams for diatomic molecules, a topic afforded about half as much space in Petrucci. Since students perceive MO to be a complex theory (i.e., antibonding orbitals), Whitten's greater coverage implies more textual difficulty. VSEPR theory, a very welcome approach to molecular geometry, is also given twice as much space in Whitten.

For what it's worth, application of the Fry Readability Graph (Edward Fry, Rutgers University Reading Center) to each text places Whitten off the chart, being written at the 17+ grade level; Petrucci checks in at slightly below the 16th grade level. On this basis, both texts are written above the reading level of their primary intended audiences.

Treatment of the less-than-conventional BF₃ molecule allows for a further comparative example of content level and textual similarity. Whitten uses nearly two pages to discuss BF₃ in terms of its Lewis formula, VSEPR predicted structure, and application of valence bond theory. Petrucci uses less than a page, concentrating on its Lewis structure and four resonance hybrid contributors. Whitten follows this up with two exercises, #7-50 asking the student to write the Lewis formula for BF₃ and noting its exception to the octet rule, and #8-44 calling for the correct hybridization in the central atom of the similarly structured BCl₃ molecule. Petrucci also has two related exercises. Problem #11-26 asks if the Lewis structure of BF₃ obeys the octet rule, while #12-8 asks the student to "Explain why the molecular structure of BF₃ cannot be described through overlaps involving pure s and p orbitals." Is imitation the sincerest form of flattery?

End-of-chapter problems abound in the texts, numbering over 2000 each and presented in a wide range of difficulty and complexity levels. Dudley Herschbach (Fall 1996 issue of Liberal Education) calls for problems that do more than provide just the right data. Both Petrucci and Whitten try to answer such a call.

While both texts appear to be error free for the most part, Whitten's "Mixed Example" problem #2-84 seems to be incorrectly composed. Both texts use the White Cliffs of Dover as examples of natural calcium carbonate, but Petrucci's page reference to it in the index is not correct, listing page 755 instead of 655.

Another selling point for both texts is the plethora of good solved examples, nearly 300 each. Many teachers spend a significant fraction of classroom instructional time going over examples. Cross-textual similarity continues. Petrucci's #18-5 asks for the mass of sodium acetate required to bring a 0.25 M acetic acid solution to a pH of 5.09. Whitten's example #18-20 asks for the mass of ammonium chloride required to bring a 0.10 M ammonia solution to a pH of 9.15.

Please allow your curiosity and interest to be aroused by reading over the following lists of features, which caught my eye in each text.

Petrucci: Focus on Polywater; color pictures visualizing carbon atoms in graphite; writing a "balanced equation" for forming a necklace from individual beads (Feature Problem C, Chapter 4); employing computer graphics to dramatize relative enthalpies of formation of compounds; Focus on the Periodic Law and Mercury; Focus on Fullerenes: Buckyballs; pictures of modern digital thermometers and pH meters; the attention paid to detail in titration calculations and demonstrations in Chapter 18; true color pictures of coordination complexes; the best picture of Marie Sklodowska Curie I've ever seen (p 898); the scanning electron microscope picture of the sticky surface of a 3M Post-It note explaining why it sticks; and the frequent pictures of postage stamps to illustrate important people and events in chemistry.

Whitten: pictures of flash bulbs on electronic balances before and after igniting; Chemistry in Use, Avogadro's Number; Chemistry in Use, The Development of Science ["geographical" elements drawn on a map of Europe]; an excellent presentation of determining simplest formulas (pp 68, 69); exercise problem #6-10 dealing with making predictions from/about the periodic table; Chapter 11 exercise problems involving ascorbic and oxalic acids; The Problem Solving Tip on p 408 dealing with gas law calculations; Chemistry in Use, Radon and Smoking; exercise problem #12-43 indicating that sodium is a major component in the atmosphere of the planet Mercury; A figure showing lead and copper atoms merging in the solid state; a picture of a modern digital thermometer; a figure demonstrating an S_N2 reaction; multiple use of pictures of digital pH meters throughout Chapter 18; good discussion and figures describing titrations in Chapter 19; Chemistry in Use, A Spectacular View of One Mole of Electrons; Valence Bond Theory applied to coordination compounds; and Chemistry in Use, C60 and the Fullerenes.

Both texts take the conventional approach in dealing with the Aufbau filling orders and electron configurations of transition metal atoms, and have figures showing mnemonic aids. But both write simplified notations as [Ar]3dⁿ4s², rather than my preference, [Ar]4s²3dⁿ, even though, as Whitten mentions (p 195), "Some sets of orbitals are so close in energy (e.g., 4s and 3d) that minor changes in their relative energies may occasionally change the order of filling". This subject will no doubt be clarified in time. Importance delegated to the subject of quantum numbers has pretty much settled out in the writing of general chemistry texts. Petrucci and Whitten once again agree, granting something less than two pages each to the subject. Only Whitten makes mention of equivalent weights and normality, concepts still used intermittently in chemistry, but infrequently given much attention today. And Whitten presents two methods of balancing redox reactions, the change of oxidation number method and the half-reaction method. Petrucci uses only the latter. Whitten clings to the older angstrom units to express atom-sized dimensions, whereas Petrucci uses picometers. Whitten employs a combined glossary/index; Petrucci separates them. Both books come equipped with the now expected full complement of manuals, study guides, transparencies, test banks, videodiscs, CD-ROMS, and the like.

Petrucci and Whitten have broad appeal with many strengths and few weaknesses. Choosing one over the other would seem to present a real dilemma.