Here's why:

* Orbitals and Electrons: Atomic orbitals are regions of space around the nucleus where there's a high probability of finding an electron.

* Pauli Exclusion Principle: This principle states that no two electrons in an atom can have the same set of four quantum numbers. One of these numbers is the spin quantum number, which can be either +1/2 or -1/2. This means each orbital can hold a maximum of two electrons, one with spin up (+1/2) and one with spin down (-1/2).

Let me know if you have any more questions!