ABSTRACT
The hydrogen atom consists of an electron and a proton interacting through an attractive Coulomb potential. In order to discuss the properties of the hydrogen atom, the chapter describes two particle systems quantum mechanically. The time rate of change of the state vector is given by Schrodinger's equation. The extraordinary degeneracy of the hydrogen atom is closely connected with the fact that the bound orbits of the classical Kepler problem, close on themselves. Thus the vector that points from the origin along the semi major axis of the orbit is a constant of the motion, which is peculiar to the Kepler problem.
