What is the maximum number of electrons that can occupy a single orbital?

The maximum number of electrons that can occupy a single orbital is two. This is a fundamental principle in quantum mechanics, specifically related to the Pauli Exclusion Principle, which states that no two electrons in an atom can have the same set of quantum numbers. Since an orbital can hold a maximum of two electrons, these electrons must have opposite spins, allowing them to coexist in the same space while adhering to this principle.

In atomic structure, orbitals are defined regions around the nucleus where there is a high probability of finding electrons. Each orbital can hold a pair of electrons, reflecting their opposite spin orientation. This is why the figure of two is critical in understanding electronic configurations in atoms.

Understanding this concept is crucial for predicting how atoms will bond and interact with each other in chemical reactions and is foundational knowledge in chemistry.