According to the Pauli Exclusion Principle, how many electrons can occupy a single atomic orbital?

The Pauli Exclusion Principle states that no two electrons in an atom can have identical quantum numbers. This principle directly relates to the occupancy of atomic orbitals. Each atomic orbital is defined by a set of quantum numbers and can hold a maximum of two electrons. These two electrons must have opposite spins, which is denoted by their spin quantum number being +1/2 for one and -1/2 for the other. This arrangement allows electrons to pair up in the same orbital while still adhering to the principle.

Understanding this fundamental concept is essential as it lays the groundwork for the structure of electrons in atoms, influencing their chemical behavior and interactions. Orbitals are formed from regions of space where electrons are likely to be found, and the limitation of two electrons per orbital provides clarity on how these regions interact during the bonding process and energy levels within atoms.