1. Ch. 4/5: Atomic Structure
Quantum Numbers

2. Quantum Numbers
specify the properties of orbitals and of electrons in orbitals
the first three numbers describe:
main energy level (n)
Shape (l)
Orientation (ml)
4th describes spin of electron (ms)

3. 1st Quantum Number (n) main energy level occupied by electron
values are all positive whole # integers (1,2,3,…)
As it increases, the electron:
has more energy
is farther from nucleus
the total number of orbitals in a level is equal to n2

4. 1st Quantum Number (n)
n # of orbitals

5. 2nd Quantum Number (l) the shape of the orbital (sublevel)
# possible shapes = energy level
4th energy level has 4 possible shapes
possible values: 0 to n-1
s: 0
p: 1
d: 2
f: 3

6. 2nd Quantum Number
Level
Sublevels
Sublevels

7. 3rd Quantum Number (ml)
the position of an orbital around the nucleus (x, y, or z direction)
has values from +l  -l
each orbital holds maximum of 2 electrons

8. 4th Quantum Number (ms) the spin state of the electron
only 2 possible directions
only 2 possible values: +½ and -½
paired electrons must
have opposite spins
-1/ /2

9. Connection to Configurations
Draw out the orbital notation for the last sublevel filled in an atom
Circle the last electron inserted in that sublevel
Find the four quantum numbers for that electron

10. Example 1
What are the 4 quantum numbers for the electron of highest energy in nitrogen?

11. Example 2
What are the 4 quantum numbers for the electron of highest energy in sulfur?

12. Example 2
What are the 4 quantum numbers for the electron of highest energy in iron?

13. Example 4
What are the 4 quantum numbers for the electron of highest energy in calcium?