Olmsted and Williams's Chemistry: The Molecular Science, now in its second edition, remains unique among general chemistry texts in the extent to which it emphasizes an atomic and molecular point of view. In the preface, the authors exhort the student to

Think molecules. Every phenomenon in chemistry has an atomic/molecular basis that can make the phenomenon easier to understand. Ask yourself what the molecules are doing and why.

And throughout the book the material is consistently presented in ways designed to help students develop this perspective.

The most obvious implementation of the authors' molecular focus is the incorporation of numerous "molecular pictures", which help to emphasize a particulate description of matter. This type of illustration has drawn considerable attention recently in this Journal and elsewhere as a way of enhancing conceptual understanding. Although several textbooks have now begun to include such diagrams in some chapters, here they are practically ubiquitous. Open to any chapter and you will find phenomena illustrated at the molecular scale: reaction mixtures demonstrating stoichiometry, solutions showing the presence of dissociated ions or intact molecules, liquid/vapor equilibria showing the physical differences between the two phases, geometrical structures of both simple and more complex molecules. Beyond these illustrations, the authors have also shaped the text itself to focus on the molecular viewpoint. In presenting kinetics, for example, they start by describing a simple reaction mechanism in molecular terms and then develop rate laws as a macroscopic ramification of the molecular behavior. Similarly, the problem-solving strategy employed throughout the text teaches the student to "think molecules" before thinking about equations, which should help foster conceptual rather than algorithmic understanding.

In the second edition, the authors have made a number of changes designed to improve the pedagogy of the text. To increase student interest, each chapter now begins with a brief exploration of a practical or contemporary application of the ideas to be developed. Chapter 8, Fundamentals of Chemical Bonding, opens with a discussion of molecular modeling, and the introduction to Chapter 11, Macromolecules, discusses the use of polymers in prosthetics. End-of-chapter problems are now presented in a paired format, in which each odd-numbered problem is followed by a similar even-numbered problem. (Odd-numbered problems appear in the student solution manual.) The student's and instructor's solution manuals were rewritten by one of the text authors and are now completely consistent with the approach used in the text.

As might be expected in a second edition, there are also some changes in content and presentation. The systematic procedure used for constructing Lewis structures has been modified, reducing its reliance on formal charges somewhat. The discussion of molecular orbitals has been simplified slightly, although it is still more extensive than that found in most texts. Several definitions and derivations in the chapters on thermodynamics have been clarified. What was Chapter 18, The Chemistry of Lewis Acids and Bases, in the first edition has been expanded into two chapters in the new edition: Chapter 18, The Transition Elements, and Chapter 19, The Main Group Elements. This change incorporates more descriptive chemistry than was present in the first edition. Finally, it appears that a number of minor errors present in the first edition have been corrected.

The second edition of Chemistry: The Molecular Science retains all the strengths of the book, including the molecular focus, the integration of organic molecules into examples throughout the text, and a large number of problems framed in the context of industrial, environmental, biological, or pharmaceutical applications. Revisions have been made which should improve the clarity of presentation for several topics. The book merits serious consideration by general chemistry instructors who are looking for a more conceptual focus than that found in many texts.

Larry Brown
Department of Chemistry
Texas A&M University
College Station, TX 77843