Analysing the whys?

Physical chemistry comprises a third of the core curriculum of most chemistry courses. On these grounds alone, it could be judged as an important branch of chemistry but, to the enthusiast, it is more. It is the all-encompassing part of chemistry that answers the question why? Why do you fall down on ice? Why are flames yellow? Why does the ozone hole form? Why can whales dive so deep and for so long? However, there is another view of physical chemistry that it is a necessary but unwelcome obstacle to be surmounted on the path to a degree in chemistry. Physical chemistry is perceived by many chemistry undergraduates to be a mathematical and therefore difficult subject. In the light of this, authors of texts on physical chemistry face a hard task. The subject is broad and only a small fraction can be presented in a single text. Though mature, having a 200-year history, it is still moving into new fields.

Each text reviewed here has a long history, takes a different approach to the topic and each has now been published in a new edition. However, the list is not really complete since it is not possible (in the United Kingdom at least) to write a review of textbooks in physical chemistry without making a comparison with the market leader in the field, Physical Chemistry by Peter Atkins. The real choice faced by students and libraries alike is whether to buy this text or one of the other texts reviewed here.

The Elements of Physical Chemistry by Atkins is the direct descendant of the benchmark text. In the original edition of Elements, Atkins stated that he wished to write a book that presented the ideas and insights within physical chemistry without burying the reader in mathematics. The third edition has been restyled following the trends introduced into later editions of his full-scale text, although the basic organisation and format remain unchanged. Observing the increased importance of molecular biology, there are frequent references to biological applications.

High-quality graphical design is a hallmark of Atkins's books. When they were introduced in his first edition of Physical Chemistry , they broke new ground in helping to present physical chemistry in an attractive way. The trend continues in this text. But the purpose of illustration seems to have been forgotten, namely to convey in visual fashion a concept that is difficult to portray in words or formulae. I have to say that I think that many of the new cartoons now have meaning only to those who teach the topic and as much effort is required to explain the diagram as the concept it seeks to portray. This is particularly true for drawings of molecular orbitals, electron densities and biomolecules. I am not convinced that it is obvious why light and dark shaded spheres are the best way to show that different orbitals have a different sign. Despite this criticism, the book provides welcome help for students daunted by mathematics, as the main concepts of physical chemistry are presented with clarity. It is a good stepping stone to more detailed texts.

I am not sure how successful the book would be for biologists, however. While undergraduate biologists, in general, have to contend with a less rigorous training in mathematics, what they really need is not physical chemistry with less mathematics, but the necessary mathematics taught in a biological context. Perhaps a biologist, realising the need for physical chemistry, would do better to seek a book written with them in mind. It was for this purpose that the second edition of Physical Chemistry for the Chemical and Biological Sciences was written, and this text has undergone the most radical revision of all the texts reviewed here. The format is modern, with wide margins, good use of diagrams, colour and numerical examples. The revised text is also substantially longer.

The most striking changes are the deletions and rearrangements. In a post-cold war, post-nuclear age, the final chapter on nuclear chemistry disappears, but statistical thermodynamics has been put in its place. In traditional texts, statistical thermodynamics joins together classical and quantum theories of matter, because it shows how to proceed from the properties of a single molecule to a beaker full of them. Despite the fundamental intellectual position of this topic, it has few day-by-day practical applications. So, if you have to compel students to learn things they do not wish to know, then it is better to focus first on classical thermodynamics and then quantum chemistry and spectroscopy.

I like this book because applications to biology are built into the very core of the exposition, and continuity with biochemistry texts is apparent. The figures are clear and drawn from the perspective of a biochemist not a graphical designer. It is a pity that the treatment of diffraction is rather dated and does not reflect the central role of protein crystallography in molecular biology, but this is a distinct and excellent publication worth recommending to biological chemists.

From the books reviewed here, Physical Chemistry by Robert J. Silbey and Robert A. Alberty can claim to have the longest family tree. The text has passed through more than 15 editions, in the hands of four authors, since its inception in 1913 as Outlines of Theoretical Chemistry by Frederick Getman. It has changed substantially since the time I struggled to learn physical chemistry with its help.

This text is the one that must be compared most directly with Atkins's Physical Chemistry , in that it is directed to a similar audience and is comparable in size and price. The topics are essentially the same too. In view of its illustrious history, it is no surprise to find that the text by Silbey and Alberty retains a more traditional flavour than that of Atkins. At the most trivial level, this is obvious from the use of two-colour tones by Atkins and the retention of black-and-white line drawings by Silbey and Alberty. However, reading the texts shows that Silbey and Alberty have a more traditional approach to teaching too. It assumes from the outset a higher level of mathematical ability. By contrast, Atkins starts with simpler mathematics and has separated physical concepts from the mathematical machinery. This is particularly true for thermodynamics, where Silbey and Alberty are more advanced and concise than Atkins. Its honest treatment of electrochemistry stands in marked contrast to the deceptive ease of both of Atkins's textbooks. The text of Silbey and Alberty would suit second-year undergraduates in the UK, but I suspect that, by this time, enthusiastic undergraduates will have already purchased a copy of Atkins's text. This is a valuable book for discerning students.

I have always regarded Physical Chemistry by R. Stephen Berry, Stuart A. Rice and John Ross as the K2 of textbooks: not the highest mountain but one of the most challenging and rewarding to climb. The thesis of this text differs from the others reviewed in its belief that physical chemistry should be taught beginning with quantum theory, from which the properties of all matter should then be derived. Quantum, atomic and molecular theory should be followed by classical and statistical thermodynamics, and reaction kinetics should finish off.

The rigour and lucidity of this text sets it apart from the others reviewed. The inclusion of non-equilibrium thermodynamics and discussion of the foundations of statistical thermodynamics, coupled with its treatment of the properties of fluids, places this text in a class of its own.

My guess is that few UK students would have the time to consult this text. This is a pity because, in spite of the tough central portion on fundamental thermodynamics, the book as a whole is very readable. Although Atkins was noted for the clarity of his exposition, his books are now so punctuated by examples, calculations and justifications that it is hard to sit down and read them. One of the joys of the text of Berry and his colleagues is that it is a good read. My only disappointment with the text lies in the extent of the revisions made for the second edition.

In the past 20 years, physical chemistry has made substantial advances in many areas: most notably in the fields of ultrafast spectroscopy, interfacial science and condensed matter. Furthermore, it has to be recognised that chemistry as a whole encompasses an increasingly large part of molecular biology. In this text, these changes are acknowledged by the inclusion of vignettes of topical areas written by world experts. However, the balance of this text has not been altered to any substantial extent and its roots remain in the traditional physical chemistry of atoms, small molecules and simple fluids. I think this is a lost opportunity, although the text remains one that every library should have.

Finally, do these texts convey a sense of excitement? I found the second one passes this test, perhaps unfairly since I have learnt something new about biology, but it is very refreshing in its aims and clarity. Berry, Rice and Ross's text also passes because there is a vision of rigour and a glimpse of modern advances but, most of all, it stretches readers beyond the confines of their undergraduate course.

Trevor Rayment is lecturer in chemistry, University of Cambridge.