This straightforward presentation emphasizes chemical applications of thermodynamics as well as physical interpretations, offering students an introduction that's both interesting and coherent. It considers chemical behavior in terms of energy and entropy, and it explains the ways in which the magnitude of energy and entropy changes are dictated by atomic properties. All concepts are presented in a simplified mathematical context, making this an ideal text for a beginning course in thermodynamics. The author considers the first and second laws of thermodynamics in turn, after which he proceeds to applications of thermodynamic principles. He devotes considerable attention to the concept of entropy, emphasizing the interpretation of entropy changes and chemical behavior in terms of qualitative molecular properties. Students gain a familiarity with the entropy concept that will form a solid foundation for later courses and more formal thermodynamic treatments.