Pauli exclusion prindple

Several explanations have been given for the physical origin of the ethane rotational barrier. One analysis attributes the barrier to the Pauli-exclusion-prindple repulsion (Section 10.3) between the eclipsing localized C—H bonding electron pairs in eclipsed ethane [R. M. Pitzer, Acc. Chem. Res., 16,207 (1983)], but several workers have rejected this explanation and offered other explanations [R. F. W. Bader et al.,... 

Pauli exclusion prindple. No two electrons in an atom can have the same four quantum numbers. (2.1)... 

Electrons fill orbitals following three principles (1) the Aufbau prindple, (2) the Pauli exclusion principle, and (3) Hund s rule. Orbitals with the same energy level are called degenerate orbitals. 

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