To understand the properties of bulk matter, principles of a subject called thermodynamics without getting into the microscopic details of atomic physics are often relevant. However, to make the connection from one atom to the Avagadro number, you need to consider the quantum behavior of atoms and the laws of statistics. In this course, we try to cover both thermodynamics and statistical mechanics. For this purpose, before the first midterm, we will cover the concepts and definitions relevant to both macroscopic (thermodynamics) and microscopic (statistical) viewpoints. After the first midterm, we will start with engines, free energy, and chemical equilibrium; later we will discuss Boltzmann statistics in detail prior to the 2nd midterm. After the 2nd midterm, we will discuss the quantum statistics, namely Fermi-Dirac and Bose-Einstein distribution functions. By the end of the semester, I expect that the students should develop a pretty good sense of how to assess and characterize a system given a proper description.