Pauli Exclusion Principle

In the early twentieth century, the problem concerning the number and the arrangement of bound electrons in an atom became a central aspect for both physicists and chemists. In this chapter, we will start from the discussion of the works of J. Rydberg[aut]Rydberg, Johannes, G. Lewis[aut]Lewis, Gilbert and I. Langmuir[aut]Langmuir, Irving, aimed at explaining the periodic table of elements. Then, we will deal with the splitting of atomic spectral lines by a magnetic field (namely, the Zeeman effect), which was discovered by P. Zeeman[aut]Zeeman, Pieter in Leiden, and, subsequently, interpreted by A. Lorentz[aut]Lorentz, Hendrik Antoon. In particular, we will focus on the anomalous Zeeman effect that, in 1925, led W. Pauli[aut]Pauli, Wolfgang Ernst to the formulation of the so-called exclusion principle and to the idea of electronic spin, first introduced by S. Goudsmit[aut]Goudsmit, Samuel Abraham and G. Uhlenbeck[aut]Uhlenbeck, George Eugene. Finally, we will return to Leiden, to briefly dwell with the experiments at very low temperatures conducted by H. Kamerlingh Onnes[aut]Kamerlingh Onnes, Heike.