What does the Pauli exclusion principle state?

The Pauli exclusion principle specifically states that no more than two electrons can occupy the same orbital, and if two electrons do occupy the same orbital, they must have opposite spins. This principle is fundamental to understanding electron configurations in atoms, as it ensures that each electron maintains its unique quantum state within an atom.

While it might seem intuitive that since electrons are negatively charged they would repel each other and occupy different spaces, the Pauli exclusion principle clarifies that a maximum of two electrons can indeed share an orbital; they simply must have opposite spins to comply with the quantum mechanical nature of electrons.

Other options do not accurately reflect the principle's meaning: the idea of electrons occupying separate orbitals (one of the incorrect answers) is more aligned with Hund's rule, which states that electrons will fill degenerate orbitals singly before pairing up. The notion that all electrons must have different energy levels also misrepresents the principle, as it is possible for multiple electrons to be in the same energy level while occupying different orbitals. Lastly, the statement regarding orbitals holding only one electron contradicts the Pauli exclusion principle, which allows for two electrons in the same orbital under specific conditions.