2. Electronic Configuration Pauli exclusion principle – no two electrons in an atom can have the same four quantum numbers.

3. Electronic Configuration Pauli exclusion principle – no two electrons in an atom can have the same four quantum numbers. Shielding may cause some orbitals to over lap.

4. Electronic Configuration Pauli exclusion principle – no two electrons in an atom can have the same four quantum numbers. Shielding may cause some orbitals to over lap. Hunds rule – the most stable arrangement of electrons in subshells is the one with greatest number of parallel spins

5. Energy Level diagrams

6. Outer shell electrons are called valence electrons Valence electrons are equal to the A group numbers