Along with its inherent interdisciplinary character, chemical physics is also a recognised science on its own. Its foundations consist of understanding chemical phenomena in terms of the most fundamental laws of physics. This book focuses on the concepts on which this science is founded rather than on the applications. The subject is presented starting from the main ideas of physics (classical, quantum and statistical) relevant to the description of phenomena of interest from the chemical point of view. The authors have taken an individual approach in their presentation of the essence of a connected theory rather than mere explanations of apparently unrelated facts. Audience: The book will be useful to advanced undergraduate and graduate students in fields such as chemistry, physics, materials science, engineering and biology, where there is a need for a knowledge of chemistry which includes, beside the presentation of facts, their explanation in terms of general principles.