This text differs from most statistical thermodynamics textbooks in that it does not deal exclusively with statistical aspects of thermodynamics. Instead, it attempts to weave together statistical and classical elements to develop the full theoretical framework of thermodynamics. Chapter 1 begins this development by establishing the basic features of energy storage at the atomic and molecular levels. It contains a very short introduction to basic aspects of quantum mechanics. The quantum models discussed in this chapter are models of energy storage modes found in common molecules. Conclusions regarding energy levels and their degeneracy for these modes of energy storage are cornerstones of the statistical thermodynamic theory developed in later chapters.

Microscale Energy Storage

Since this text is designed for graduate-level engineering instruction, it is likely that the reader has already encountered some elements of thermodynamics in previous courses and very likely that he or she has some idea of the usefulness of thermodynamic analysis for systems of scientific and technological interest. Mechanical or chemical engineers who are thoroughly versed in classical equilibrium thermodynamics may wonder what a statistical development of thermodynamics has to offer beyond the tools provided by classical thermodynamics.

In response to such an inquiry, we can identify two main benefits of developing a statistical thermodynamic theory. First, by design, statistical thermodynamics theory provides a link between macroscopic “classical” thermodynamic analysis of system behavior and the microscopic characteristics of the atoms, molecules, or subatomic particles that make up the system.