In the preparation of the fourth edition, we have been guided by the collective wisdom of over fifty reviewers who are experts in one of the three subdisciplines covered in the book and who represent a diversity of experience, including community colleges, and four-year colleges and universities. We have retained the core approach of our successful earlier editions, modernized material where necessary, and expanded or removed material consistent with retention of the original focus and mission of the book. Throughout the project, we have been careful to ensure that the final product is as student-oriented and readable as its predecessors.

• Chapters 1 and 2 have been rearranged to more smoothly facilitate students' transition from descriptive to quantitative chemistry.
• Twenty new boxed elements, particularly in the Organic and Biochemistry parts, give students insight into the modern-day application of various topics.
• Approximately 200 new end-of-chapter questions will allow instructors greater flexibility in assigning problems and will give students more opportunity to test themselves.
• The website and other media supplements, as described later in this Preface, have been enhanced.

Specifically, the Digital Content Manager, a CD-ROM, contains electronic files of text figures and tables as well as PowerPoint lecture slides.