Electron Configurations in Atoms (II)
When the ? value is greater than 0 there are m? substates, which can not be indicated in simple filling diagrams (nsxmpyetc).
Example, He 1s3p does not indicate which m? the second electron occupies. We have to keep in mind the number of substates, and find another way to indicate which are occupied.
The “Aufbau” principle, the “building up” principle, governs many electrons in the ground state (lowest energy state) of atoms. We keep adding electrons, one at a time, trying to keep them in the lowest energy levels open for occupancy.