In this new textbook on physical chemistry, fundamentals are introduced simply yet in more depth than is common. Topics are arranged in a progressive pattern, with simpler theory early and more complicated theory later. General principles are induced from key experimental results. Some mathematical background is supplied where it would be helpful. Each chapter includes worked-out examples and numerous references. Extensive problems, review, and discussion questions are included for each chapter. More detail than is common is devoted to the nature of work and heat and how they differ. Introductory Caratheodory theory and the standard integrating factor for dGrev are carefully developed. The fundamental role played by uncertainty and symmetry in quantum mechanics is emphasized. In chemical kinetics, various methods for determined rate laws are presented. The key mechanisms are detailed. Considerable statistical mechanics and reaction rate theory are then surveyed.