In the 1920s, Bohr's atomic model had already been presented to the world, but it still underwent improvements that had the participation of other physicists. Who most stood out in studies related to the improvement of Bohr's atomic model was the German physicist Arnold Sommerfeld.
Spin was born out of an attempt to understand and explain why the spectrum of hydrogen and other atoms had multiple lines, like the Zeeman effect.
They then came to the conclusion that spin is the angular motion of the electron, that is, the motion of the electron has elliptical orbits, which obey Kepler's Laws and are responsible for the transition of small differences in energy.
Before the discovery of the electron spin, the analyzed atom's orbit was done through quantum numbers. They were responsible for relating the energy levels of the electron, the orbital shape held by the electron and also the description of the spatial quantization made by it.
In 1925, the Austrian physicist Wolfgang Pauli, when analyzing spectra, observed that the number of electrons was not repeated in the same atom. As in each orbital there are only two electrons, these necessarily need to have different energies.
Paulli postulated spin exclusion when he observed that the electron has the same amount of quantum numbers in the same atom, thus defining the electronic structure of atoms.
By Talita A. angels
Graduated in Physics
Brazil School Team
Physics Modern - Physics - Brazil School
Source: Brazil School - https://brasilescola.uol.com.br/fisica/o-spin-eletron-principio-exclusao.htm
