Question

According to the quantum mechanical model of the atom what is the maximum number of electrons that can occupy each energy level?

Answer 1

Think of it in terms of orbitals (which correspond to the blocks in the periodic table) - s can hold 2, p can hold 6, d up to 10, f up to 14.

Explanation:

Increasing principal quantum numbers (typically referred to as 'shells' in pre-sixteen courses) can have progressively more orbitals e.g. one has only s (2 electrons in total), 2 has s and p (8 max), 3 has s,p and d (18 max), etc. This is all part of basic quantum theory.