Lord Ernest Rutherford, 1908 Nobel Laureate in Chemistry, put it bluntly:Science is divided into two categories: physics and stamp collecting.But he would have been astonished to see the transformation of biology from "stamp collecting" into molecular biology, genomics, biochemistry, and biophysics in this century. This transformation occurred only because, time and time again, fundamental advances in theoretical physics drove the development of useful new tools for chemistry. Chemists in turn learned how to synthesize and characterize ever more complex molecules, and eventually created a quantitative framework for understanding biology and medicine.This book presents the physical, mathematical, and statistical concepts necessary for understanding the structure and function of molecules. The emphasis is placed on understanding the critical core material in quantum mechanics, thermodynamics, and spectroscopy that should be understood by any scientist or student of science. It is designed to enhance any general chemistry text by reintroducing concepts that require a little mathematical sophistication. It is also useful as a stand-alone background text for introductions to materials science, biophysics, and clinical imaging.