The fourth edition of General, Organic, and Biochemistry, like our earlier editions, has been designed to help undergraduate majors in health-related fields understand key concepts and appreciate the significant connections between chemistry, health, and the treatment of disease. We have tried to strike a balance between theoretical and practical chemistry, while emphasizing material that is unique to health-related studies. We have written at a level intended for students whose professional goals do not include a mastery of chemistry, but for whom an understanding of the principles and practice of chemistry is a necessity. While we have stressed the importance of chemistry to the health-related professions, this book was written for all students that need a one or two semester introduction to chemistry. Our focus on the relationship between chemistry, the environment, medicine, and the function of the human body is an approach that can engage students in a variety of majors.

In this text we treat the individual disciplines of inorganic, organic, and biological chemistry. Moreover, we have tried to integrate these areas to show the interrelatedness of these topics. This approach provides a sound foundation in chemistry and teaches students that life is not a magical property, but rather is the result of a set of chemical reactions that obey the scientific laws.

Key Features of the Fourth Edition

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.

We designed the fourth edition to promote student learning and facilitate teaching. It is important to engage students, to appeal to visual learners, and to provide a variety of pedagogical tools to help them organize and summarize information. We have utilized a variety of strategies to accomplish our goals.

Students learn better when they can see a clear relationship between the subject material they are studying and real life. We wrote the text to help students make connections between the principles of chemistry and their previous life experiences and/or their future professional experiences.

• Boxed Readings--"Chemistry Connection": We have crafted introductory vignettes to allow the sudent to see the significance of chemistry in their daily lives and in their future professions.
• Boxed Perspectives: These short stories present realworld situations that involve one or more topics that students will encounter in the chapter. The "Medical Perspectives" and "Clinical Perspectives" relate the chemistry to a health concern or a diagnostic application. The "Environmental Perspectives" deal with issues, including the impact of chemistry on the ecosystem and the way in which these environmental changes affect human health. "Human Perspectives" delve into chemistry and society and include such topics as gender issues in science and historical viewpoints.

In the fourth edition, we have added 20 new boxed topics and have updated many of the earlier ones. We have tried to include topics, such as self-tanning lotions and sugar substitutes, which are of interest to students today.

We have included the most recent strategies for treatment of AIDS and new information on the use of genetic engineering to treat a variety of genetic diseases.

• Learning Goals: A set of chapter objectives at the beginning of each chapter previews concepts that will be covered in the chapter. Icons locate text material that supports the learning goals.
• Detailed Chapter Outline: A detailed listing of topic headings is provided for each chapter. Topics are divided and subdivided in outline form to help students organize the material in their own minds.
• Chapter Cross-References: To help students locate the pertinent background material, references to previous chapters, sections, and perspectives are noted in the margins of the text. These marginal crossreferences also alert students to upcoming topics that require an understanding of the information currently being studied.
• Chapter Summary: Each major topic of the chapter is briefly reviewed in paragraph form in the end-of chapter summary. These summaries serve as a ministudy guide, covering the major concepts in the chapter.
• Key Terms: Key terms are printed in boldface in the text, defined immediately, and listed at the end of the chapter. Each end-of-chapter key term is accompanied by a section number for rapid reference.
• Summary of Key Reactions: In the organic chemistry chapters, each major reaction type is highlighted on a green background. These major reactions are summarized at the end of the chapter, facilitating review.
• Glossary of Key Terms: In addition to being listed at the end of the chapter, each key term from the text is also defined in the alphabetical glossary at the end of the book.
• Appendix Material: Each Appendix accomplishes one of two goals: remediation or expansion of information introduced in the chapter.

• Dynamic Illustrations: Each chapter is amply illustrated using figures, tables, and chemical formulas. All of these illustrations are carefully annotated for clarity.
• Color-Coding Scheme:We have color-coded the reactions so that chemical groups being added or removed in a reaction can be quickly recognized. Each major organic reaction type is highlighted on a green background. The color-coding scheme is illustrated in the "Guided Tour" section of this book.
• Computer-Generated Models: The students' ability to understand the geometry and three-dimensional structure of molecules is essential to the understanding of organic and biochemical reactions. Computergenerated models are used throughout the text because they are both accurate and easily visualized.

• In-Chapter Examples, Solutions, and Problems: Each chapter includes a number of examples that show the student, step-by-step, how to properly reach the correct solution to model problems. Whenever possible, they are followed by in-text problems that allow the students to test their mastery of information and to build self-confidence.
• In-Chapter and End-of-Chapter Problems:We have created a wide variety of paired concept problems. The answers to the odd-numbered questions are found in the back of the book as reinforcement for the students as they develop problem-solving skills. However, the students must then be able to apply the same principles to the related even-numbered problems.
• Critical Thinking Problems: Each chapter includes a set of critical thinking problems. These problems are intended to challenge the students to integrate concepts to solve more complex problems. They make a perfect complement to the classroom lecture, because they provide an opportunity for in-class discussion of complex problems dealing with daily life and the health care sciences.

Over the course of the last three editions, hundreds of reviewers have shared their knowledge and wisdom with us, as well as the reaction of their students to elements of this book. Their contributions, as well as our own continuing experience in the area of teaching and learning science, have resulted in a text that we are confident will provide a strong foundation in chemistry, while enhancing the learning experience of the students.