This is an introduction to statistical mechanics, intended to be used either in an undergraduate physical chemistry course or by beginning graduate students with little undergraduate background in the subject. It assumes familiarity with thermodynamics, chemical kinetics and the kinetic theory of gases, and quantum mechanics and spectroscopy, at the level at which these subjects are normally treated in undergraduate physical chemistry. Ideas, principles, and formulas from them are appealed to frequently in the present work.

If statistical mechanics constituted about 10% of a physical chemistry course it would be covered in 8 to 12 lectures, depending on whether the course as a whole were taught in two semesters or three. There is enough material in these chapters for 12 lectures (or more). The instructor who has only 8 available will have to be selective. The most technical parts, and so the likeliest candidates for omission or contraction, are the treatment of ortho- and para-hydrogen, which is part of §2.4 of Chapter 2, that of molecular dynamics and Monte Carlo computer simulations in Chapter 7 (§§7.3 and 7.4), and that of the quantum ideal gases in Chapter 8, which includes a discussion of the grand partition function (§8.2).

Because only a relatively short time may be devoted to the subject it is important to arrive quickly at the usable formulas and important applications while still keeping the level consistent with that of an undergraduate physical chemistry course.