Which principle states that no two electrons can have the same set of quantum numbers?

The principle indicating that no two electrons in an atom can have the same set of quantum numbers is the Pauli Exclusion Principle. This principle is fundamental to the understanding of electron configuration in atoms. Quantum numbers describe the specific characteristics of electrons, including their energy level, shape of the orbital, orientation, and spin. According to this principle, since every electron in an atom is uniquely described by its set of quantum numbers, if two electrons occupy the same orbital, they must have opposite spins. This concept is crucial for explaining the arrangement of electrons in atoms and their subsequent chemical behavior.

In contrast, the Aufbau Principle deals with the order in which electrons fill the atomic orbitals, typically starting from the lowest energy level. Hund's Rule states that electrons will fill degenerate orbitals singly before pairing up, to minimize electron-electron repulsion. The Heisenberg Uncertainty Principle highlights the limits of simultaneously knowing certain pairs of properties (like position and momentum) of a particle. However, none of these principles address the uniqueness of quantum numbers for electrons in an atom as explicitly as the Pauli Exclusion Principle does.