The study of atomic spectroscopy was central to the development of modern quantum mechanical theory. Thus, applications to the field of atomic physics are an important feature of any course in quantum mechanics. However, the converse is not necessarily true – a comprehensive course in atomic physics is not simply a study of quantum mechanics. The aspects of atomic physics that are most useful as illustrative examples for a quantum mechanics course usually involve either hydrogen or helium, and the methods used for these systems are very specialized and not particularly exemplary of the methods used for the study of complex atoms and ions. Graduate atomic physics courses often substitute for increased complexity of the atomic system studied an increased elegance in the theoretical representation of the one-electron system. Thus, a course on the Schrödinger theory of hydrogen is followed by a course on the Dirac theory of hydrogen, and that in turn is followed by a course on the quantum electrodynamic theory of hydrogen.

In the study of complex, many-electron spectra, the precision of the optical measurements greatly exceeds the accuracy that can be obtained with even the most sophisticated of currently available theoretical codes. Therefore, predictions based on these very high precision measurements usually rely on semiempirical methods, often utilizing simple semiclassical or parametrized single-particle models.

The approach adopted here will be to provide conceptual and intuitive insights into quantum mechanical phenomena, drawing on measured data, semiclassical models, and semiempirical parametrizations that reveal unexpected regularities among various atomic systems. While quantum mechanics has delegitimized the hope of ab initio quantitative predictability based on conceptual pictures, there is more to physics than mathematics.