According to the Pauli exclusion principle, what is the maximum number of electrons that an orbital can hold?

The Pauli exclusion principle states that no two electrons in an atom can have the same set of quantum numbers, which means that an orbital can hold a maximum of two electrons. These two electrons must have opposite spins, often referred to as "spin-up" and "spin-down."

In the context of atomic orbitals, each orbital is represented by a specific shape, such as s, p, d, or f. Regardless of the type of orbital, the restriction of the Pauli exclusion principle dictates that while one electron can occupy the orbital with one quantum state (spin), another electron can occupy the same orbital but must have a different quantum state (the opposite spin).

This principle ensures that electrons within the same orbital are differentiated by their spin quantum number, leading to a maximum occupancy of two electrons per orbital. Thus, the correct interpretation of the principle aligns with the notion that only two electrons can share the same space in an orbital, provided they have opposing spins.