- Electron configuration describes the arrangement of electrons in an atom's orbitals and energy levels according to 4 quantum numbers. - The Pauli Exclusion Principle states that no two electrons can have the same set of 4 quantum numbers. - Elements are arranged on the periodic table based on their electron configurations, with groups reflecting which orbitals are being filled. - A noble gas configuration can be used to abbreviate long electron configurations by writing the nearest noble gas followed by the remaining electrons.