This book bridges the gap between the descriptive treatment of most introductory texts and the theoretical accounts found in graduate-level texts. The authors present a concise, condensed sequence of physical principles that link macroscopic mechanical, thermal, and electrical phenomena to their microscopic quantum origin, statistical description, and atomic structure. The book provides solid coverage of the subject matter using simple models and allows contact with the behavior of real phenomena, real substances, and aspects of present-day research. Each chapter contains examples, Applications sections illustrate the core topics, and Notes sections address more advanced topics.