|This is an extensive revision of a successful and innovative introductory text for students of college and university physics. Like the first edition, this revision concentrates on the physics that answers the question: Why do we believe in atoms and their properties? While providing a sound introduction to basic physical concepts, it emphasizes nineteenth- and twentieth-century physics that has led to our modern picture of the atom. The revision also has two new chapters that explore, in the context of real experiments, important ideas of quantum mechanics - including disturbing consequences of superposition such as entanglement, non-locality, and the violation of Bell's inequalities. The book begins with a review of Newtonian mechanics. It then looks at physical evidence that chemical compounds are made of atoms and shows how basic mechanics and a simple hard-sphere model of atoms explain pressure, temperature, viscosity, and the ideal gas laws, and yield the first determination of the size of an atom. ... The book has a large number of problems to help students clarify their understanding. The spreadsheet problems have been updated, and new problems have been added to many chapters. Like most of the problems in the first edition, the new ones are original creations for this book.