Physical chemistry is the study of macroscopic and microscopic phenomena
in chemical systems in terms of the principles, practices, and concepts of
physics such as motion, energy, force, time, thermodynamics, quantum
chemistry, statistical mechanics, analytical dynamics and chemical equilibria.
Physical chemistry, in contrast to chemical physics, is predominantly (but not
always) a supra-molecular science, as the majority of the principles on which
it was founded relate to the bulk rather than the molecular or atomic
structure alone (for example, chemical equilibrium and colloids).