Emphasizes the understanding of thermal properties such as heat capacity, thermal expansion, and transitions in terms of the entropy and the other thermodynamic functions. Develops the relationships of the Gibbs and Helmholtz functions to equilibrium systems, reactions, and phase diagrams. Atomistic and statistical mechanical interpretations of crystalline and non-crystalline solids are linked to the general thermodynamical laws by the partition function. Nonequilibrium and irreversible processes in solids are discussed.