1. Quantum Numbers How to find your atom’s address in the Periodic Table Hotel

2. 4 Quantum Numbers No 2 electrons can have the same 4 quantum for an atom of the same element

3. When n = 4

4. 1 st Quantum Number Principle Quantum Number Gives the size of the electron cloud and increases with increasing energy levels Symbol is n n = period # in s,p n = period #-1 in d n = period #-2 in f

5. 2 nd Quantum Number Describes the sublevels with in n Sublevels are designated s, p, d, f Symbol is l The second quantum is equal to the number of sublevels. The values of l range from 0 to n – 1 For sublevels l is: s is 0 p is 1 d is 2 f is 3

6. 3 rd Quantum Number Describes the electrons angular momentum or direction in space This designates the axis as x, y, or z Symbol is m Possible values range from - l to + l

7. 4 th Quantum Number Refers to the direction of the electrons spin Pauli Exclusion Principle states that 2 electrons in the same orbital must have opposite spins 1 is clockwise, 1 is counterclockwise Symbol is s Values are +1/2 to – 1/2

8. Rules for Filling Orbitals 1.Aufbau Principle: electrons fill the lowest energy level first. Starting with n=1 filling 1s 2.Hund’s Rule: electrons must fill each orbital with in a block (p,d,f) in one spin direction before they pair 3.Pauli Exclusion Principle: 2 electrons in the same orbital must have opposite spins