Lesson

1. The Four Quantum
Numbers

2. Quantum mechanics
•It requires of 4 quantum numbers to describe to the
distribution and behavior of electrons in atoms.
•They derive from the Equation of Schrödinger for
the hydrogen atom.
•The Quantum Numbers are: n l m s

3. Quantum Numbers
n = Level of Energy, main quantum number.
values = 1, 2, 3……7
l = Sublevel of Energy, secondary quantum number.
If n = 1 then l = 0. If n = 2 then l = 0 y 1
m = Direction of the orbital ones, quantum number
magnetic.
If l = 0 then m = 0. If l= 1…. m = -1, 0 y 1
s = spin or turn of electrons, quantum number of spin
electronic. Their values are + ½ up and right and
- ½ down and left.

4. The Four Quantum Numbers
Quantum
Number
Name Relation Values
n
l
m
s
Principal Quantum Number
Secondary Quantum Number
Azimutal
Quantum Number Magnetic
Quantum Number:
electronic spin
Determines the level of Energy
of an orbital
Sublevel: it indicates Form of
the orbital.
s (sharp), p (principal),
d (difuses) y f (fundamental)
It describes the Orientation of
the orbitals in the space,
by effect of a magnetic
external field
It indicates spin of electrons
1, 2, 3, 4,.......7
Depend on the value of n
If n = 1, l = 0
If n = 2, l = 0 y 1
If n = 3, l = 0, 1 y 2
Depend on the value of m
If l = 0, m = 0
If l = 1, m = -1 0 1
If l = 2, m = -2 –1 0 1 2
+ ½ - ½
up down
favor of mr against mr

5. Atomic Orbitals: s, p, d, f

6. Representations of the
cloud of orbitals “s”

9. Representations of
the orbitals “p”

10. Group of 3 orbitals “P”
on their 3 axis: Px, Py, Pz

11. Number of electrons by
Energy level
n No. of
Sublevels
OrbitalType No. of Orbitals No. of Maximum
electrons per
sublevel
No. of Máx. Total electrons
per level
2
8
18
32
1 1 1s 1 2
2 2 2s 1 2
2p 3 6
3 3 3s 1 2
3p 3 6
3d 5 10
4 4 4s 1 2
4p 3 6
4d 5 10
4f 7 14

12. Sample Problems

13. Bibliography
Burns, R. (2003) Fundamentos de Química. 4ª Ed. Pearson,
Prentice-Hall. México, D. F.