Prentice Hall: Upper Saddle River, NJ 07458, 2001. 1256pp.
ISBN 0-13-027805-X. Paperback, $105.

When asked to do this review, I spotted ten different physical chemistry texts on my bookshelf, not counting various editions. Why so many texts? In ten years of teaching, I don't think that I have ever had more than 15 students in my physical chemistry class. The authors can't be driven by market demand. Perhaps as physical chemistry instructors, they realize that it is typically a difficult subject for many students. The various texts may represent different approaches to teaching physical chemistry.

With this thought in mind, I examined Professor Raff's text, to see if I could discern his approach. The text starts out conventionally. A periodic table, physical constants, conversion factors, Greek alphabet, and SI prefixes line the inside covers. The chapters are grouped into five sections: Classical Thermodynamics (Chapters 1-9), Quantum Mechanics and Bonding (Chapters 10-14), Spectroscopy (Chapters 15, 16), Statistical Mechanics (Chapters 17, 18), and Kinetics and Dynamics (Chapters 19, 20). There are appendices for thermodynamic data, crystal lattice energies, conversion factors (a bit more extensive than the conversion factors on the inside cover), and ionization constants for acids and bases. This breaks with the "Big Three", classical thermodynamics, kinetics, and quantum mechanics, followed by most texts. It also tends to reflect the greater emphasis on spectroscopy in modern physical chemistry.

Principles of Physical Chemistry contains all the information necessary for teaching physical chemistry in one year. I don't typically get to really know a textbook until I use it. This involves preparing lectures, going through examples and derivations, and also solving the problems assigned to students. I decided to choose Chapter 12, "Translational, Rotational, and Vibrational Energies of Molecular Systems", for this level of examination. It covers material that can be quite abstract and difficult for students to understand.

Raff is thorough in his derivations of topics such as a "Particle in a Box" but not to the exclusion of all else. He takes the time to explain why the derivation proceeds this way or that and why he chooses this solution over another. He tries, as most physical chemistry instructors do, to provide a physical picture of the topic and its solution. He doesn't assume that the student will know this is a trivial solution, he takes the time to explain why it is trivial. As most texts do, he also points out how the quantum mechanical result differs from the classical mechanical result.

Early on, the author defines a wavenumber with regard to translational energy. Subsequent derivations and examples make use of the wavenumber, k. This certainly makes the math much tidier but I'm not certain it helps the student understand the topic any better. One thing I did like: after going through an example in the text, Raff would refer the reader to similar problems at the end of the chapter.

In general, the author makes a real attempt to provide physical explanations and examples to accompany the mathematical derivations involved in quantum mechanics. I have been using tunneling electron microscopy (TEM) in my classes as an example of quantum mechanical tunneling. Though TEM has been around since the 1980s I haven't seen it used as an example in any physical chemistry text. I was delighted to see Raff use this example in his text. A diagram is provided to show how TEM works along with a microscope image. I also liked the two-dimension plots of d and f eigenfunctions, since most texts limit their plots to s and p eigenfunctions. These things go a long way to provide a physical picture for the student. I was present when an author of a physical chemistry text asked an undergraduate what she thought about his book. The student responded: "There aren't any pictures!" Certainly the math can be difficult and a great deal of effort must be given to guide the student through this process. A physical picture of the process can help guide students when they have gotten lost in the math. Professor Raff seems focused on providing this picture with some concrete real examples, images, plots, and textual explanations. As in the above examples, he is successful in most cases. On rare occasions, as in his explanation of superposition of states using a deck of cards, it didn't work very well for me. I was also surprised to find that group theory is not treated at all in the text.

Every chapter is followed by a summary of key concepts and equations. In the case of Chapter 12, this was 5 pages long. As Chapter 12 covered 78 pages, this can help students determine the important topics and not get lost in the details. It might help them review for a test. There were 63 problems at the end of Chapter 12. No answers are provided within the text. It is hard to avoid some types of problems, so some of them will be familiar to instructors. Raff provides a little humor in some of his problems (as he also did in the rest of the chapter). One problem takes place in a Las Vegas casino and a couple of problems involve a student named Sam (which could be popular at my institution).

In some texts, the problems are broken down into categories: qualitative problems, problems involving calculus, etc. This is not done here. Problems requiring a computation device are marked with an asterisk and problems using a lot of plotting are marked with a pound sign. Only 6 of the 63 problems in Chapter 12 contained these symbols. With 63 problems, there is a nice variety to choose from, and I was comfortable with the level of difficulty in the problems. I would say that the early problems were a bit simpler than the later problems but there wasn't a huge difference. I'm not convinced that the author intended to scale the level of difficulty from beginning to end. He seemed guided by the order of topics in the chapter. There is no chapter, appendix, or inside cover devoted to calculus, table of integrals, series, etc. Some of these things are covered in the chapters. I found "The Mathematics of Quantum Mechanics" in Chapter 11. It would probably be best if students had a table of integrals or math handbook when working the problems.

I enjoyed reading Raff's book. Some texts take a simple approach to physical chemistry, avoiding some of the more difficult topics. Others seem aimed at students who plan to pursue physical chemistry in graduate school. I would put Principles of Physical Chemistry in the middle; it is thorough yet it should work for students who will never study physical chemistry again. I hadn't thought of changing my current physical chemistry text but Raff's book has caused me to reconsider that decision. Ultimately, it isn't what physical chemists think of this book that matters, but how students find this introduction to the field. I think that students could do well following Professor Raff's thoughtful path and I wish them all well on that journey.