| A | B |
|---|
| Aufbau principle | an electron occupies the lowest-energy orbital that can receive it |
| electron configuration | arrangement of electrons in an atom |
| highest occupied energy level | e- containing main energy level with the highest principal quantum number |
| Hund's rule | equal energy orbitals each get a single e- before any gets a 2nd; single e- all have the same spin |
| inner shell electrons | electrons not in the highest occupied energy level |
| noble gases | group 18 elements |
| noble gas configuration | outer main energy level is fully occupied usually by 8 e- |
| Pauli exclusion principle | within an atom, electrons can not have identical quantum numbers |
