1. Multi-Electronic Atoms
The “electron correlation problem”
Total energy of the electron
Since electron pathways are unknown…electron-electron repulsions can not be calculated exactly
Electrostatic interactions will influence the potential energy
nucleus-electron
(attractions)
electron-electron
(repulsions)

2. Zeff = Zact – repulsive effects
Potential energy electron possesses as a result of what it appears to feel from the nucleus can be simulated in the Wave Equation to calculate possible positions were electron can be found:
The amount of energy the electron must receive to be taken to the infinite energy level
produces
2p+
2p+ e- e- e-
Hydrogen-like orbitals
He the atom
He the ion
Ionization energy = 3.94 x kJ
Ionization energy = x kJ
Charge felt by the electron from the nucleus is apparently lessened!

3. Rules for configuring electrons in orbitals
The AUFBAU Principle: Fill up the lowest energy orbitals available first.
The PAULI EXCLUSION Principle: No electron in the same atom can have the same set of quantum numbers (i.e. only two electrons per orbital).
HUNDS Rule: Fill up degenerate orbitals individually with the same spin before you pair them up.

4. x 1s
2s 2p
3s 3p 3d
4s 4p 4d 4f
5s 5p 5d 5f
6s 6p 6d 6f
7s 7p 7d 7f

5. Outermost Configuration & Number of Unpaired Electrons
Outside Desks ….Hafnium
5d2, 2 unpaired electrons
Inside Desks ….Holmium
4f11, 3 unpaired electrons