  After the discovery of element 93 neptunium by Edwin McMillan and Philip H.
Abelson in 1941, Maria Goeppert Mayer applied the Thomas-Fermi model to
calculate the electronic configuration of heavy elements and predicted the
occurrence of a second rare-earth series in the vicinity of elements 91 or 92
extending to the transuranic elements. Mayer was motivated by Enrico Fermi, who
was at the time contemplating military uses of nuclear energy. Historical
development of nuclear science research leading to Mayer's publication is
outlined. Mayer's method is introduced with the aid of a computer, which
enables students to visualize her description of eigenfunctions, particularly
the sudden change of spatial distribution and eigenenergy at the beginning of
the rare-earth series. The impact of Mayer's work on the periodic table is
discussed.
