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In quantum mechanics, the Pauli exclusion principle ... In 1922, Niels Bohr updated his model of the atom by assuming that certain numbers of electrons ...
The Bohr–Sommerfeld model (also known as the Sommerfeld model or Bohr–Sommerfeld theory) was an extension of the Bohr model to allow elliptical orbits of electrons around an atomic nucleus. Bohr–Sommerfeld theory is named after Danish physicist Niels Bohr and German physicist Arnold Sommerfeld .
In 1921 Pauli worked with Bohr to create the Aufbau Principle, which described building up electrons in shells based on the German word for building up, as Bohr was also fluent in German. Pauli proposed in 1924 a new quantum degree of freedom (or quantum number ) with two possible values, to resolve inconsistencies between observed molecular ...
The main and final accomplishments of the old quantum theory were the determination of the modern form of the periodic table by Edmund Stoner and the Pauli exclusion principle, both of which were premised on Arnold Sommerfeld's enhancements to the Bohr model of the atom. [5] [6]
Pauli formulated his exclusion principle, stating, "There cannot exist an atom in such a quantum state that two electrons within [it] have the same set of quantum numbers." [39] A year later, Uhlenbeck and Goudsmit identified Pauli's new degree of freedom with the property called spin whose effects were observed in the Stern–Gerlach experiment.
Taking a hydrogen molecule-like system (i.e. one with two electrons), one may attempt to model the state of each electron by first assuming the electrons behave independently (that is, as if the Pauli exclusion principle did not apply), and taking wave functions in position space of () for the first electron and () for the second electron.
Bohr, with his Aufbau or "building up" principle, and Pauli with his exclusion principle connected the atom's electronic quantum numbers in to a framework for predicting the properties of atoms. [9] When Schrödinger published his wave equation and calculated the energy levels of hydrogen, these two principles carried over to become the basis ...
The Bohr model of the chemical bond could not explain the properties of the molecules. Attempts to improve it have been undertaken many times, but have not led to success. [3] A working theory of chemical bonding was formulated only by quantum mechanics on the basis of the principle of uncertainty and the Pauli exclusion principle. In contrast ...