To address dynamic changes in how courses are structured and how students learn—variable math and reading preparation, less time for traditional studying, electronic media as part of lectures and homework, new challenges and options in career choices—the author and publisher consulted extensively with students and faculty. Based on their input, we developed the following ways to improve the text as a whole as well as the content of individual chapters.

Global Changes to the Entire Text

Writing style and content presentation. Every line of every discussion has been revised to optimize clarity, readability, and a more direct presentation. The use of additional subheads, numbered (and titled) paragraphs, and bulleted (and titled) lists has eliminated long unbroken paragraphs. Main ideas are delineated and highlighted, making for more efficient study and lectures. As a result, the text is over 20 pages shorter than the Second Edition.

More worked problems. The much admired—and imitated—four-part (plan, solution, check, practice) Sample Problems occur in both data-based and molecular-scene format. To deepen understanding, Follow-up Problems have worked-out solutions at the back of each chapter, with a road map when appropriate, effectively doubling the number of worked problems. This edition has 15 more sample problems, many in the earlier chapters, where students need the most practice in order to develop confidence.

Art and figure legends. Figures have been made more realistic and modern. Figure legends have been greatly shortened, and the explanations from them have either been added to the text or included within the figures.

Page design and layout. A more open look invites the reader while maintaining the same attention to keeping text and related figures and tables near each other for easier studying.

Section summaries. This universally approved feature is even easier to use in a new bulleted format.

Chapter review. The unique Chapter Review Guide aids study with problem-based learning objectives, key terms, key equations, and the multistep Brief Solutions to Followup Problems (rather than just numerical answers).

End-of-chapter problem sets. With an enhanced design to improve readability and traditional and molecular-scene problems updated and revised, these problem sets are far more extensive than in other brief texts.

Content Changes to Individual Chapters

• Chapter 2 presents a new figure and table on molecular modeling, and it addresses the new IUPAC recommendations for atomic masses.
• Discussion of empirical formulas has been moved from Chapter 2 to Chapter 3 so that it appears just before molecular formulas.
• Chapter 3 has some sample problems from the Second Edition that have been divided to focus on distinct concepts, and it contains seven new sample problems.
• Chapters 3 and 4 include more extensive and consistent use of stoichiometry reaction tables in limiting-reactant problems.
• Chapter 4 presents a new molecular-scene sample problem on depicting an ionic compound in aqueous solution.
• Chapter 5 includes a new discussion on how gas laws apply to breathing.
• Chapter 5 groups stoichiometry of gaseous reactions with other rearrangements of the ideal gas law.
• Chapter 17 makes consistent use of quantitative benchmarks for determining when it is valid to assume that the amount reacting can be neglected.