1. Quantum Numbers
Quantum Numbers specify the properties of atomic orbitals and their electrons
There are four quantum numbers:
principal quantum number
orbital quantum number
magnetic quantum number
spin quantum number

2. Principal Quantum Number
The principal quantum number (n) specifies the main energy levels around the nucleus
As n increases, the distance from the nucleus increases (So as the numbers become larger the levels become further from the nucleus)
Currently the values for n are 1 to 7
These orbitals are called subshells or sublevels
The four most common Principal quantum numbers are given letter abbreviations
s, p, d, f

3. Orbital Quantum Number
Orbital Quantum Number ( l ) indicates the shape of the orbital where the electron can be found
Begin 1st

4. “s” Orbital

5. “p” Orbital

6. “d” Orbital

7. “f” Orbital

8. Magnetic Quantum Number
3. Magnetic Quantum Number (ml ): indicates the orientation of an orbital about the nucleus
it tells which axis that sublevel is located on (x, y, or z axis)

9. Spin Quantum Number
The Spin Quantum Number (s) is a value (of 1/2) that describes the angular momentum of an electron. An electron spins around an axis and has both angular momentum and orbital angular momentum. Because angular momentum is a vector, the Spin Quantum Number (s) has both a magnitude (1/2) and direction (+ or -)

10. Begin 3rd 2-15-2000 Using Quantum Numbers
Quantum numbers can be used to write electron configurations
Electron configurations show how electrons are most likely distributed around the nucleus
Begin 3rd

11. Rules for Electron Configurations
1. Aufbau Principle: Electrons enter orbitals of lowest energy first
2. Hund’s Rule: Orbitals of equal energy are each occupied by one electron before any one orbital is occupied by a second electron
Begin 5th

12. Rules for Electron Configurations
3. Pauli Exclusion Principle: an atomic orbital may describe at most two electrons
The maximum number of electrons in any orbital is “2”
No two electrons in the same atom can have the same set of four quantum numbers

13. Guidelines for Electron Configurations
1. Determine number of electrons
2. Each orbital can hold 2 electrons 3.
A “ s ” sublevel has 1 orbital and holds 2 electrons
A “ p ” sublevel has 3 orbitals and holds 6 electrons
A “ d ” sublevel has 5 orbitals and holds 10 electrons
A “ f ” sublevel has 7 orbitals and holds 14 electrons

14. Order of Filling of Energy Levels
2s 2p
3s 3p 3d
4s 4p 4d 4f
5s 5p 5d 5f
6s 6p 6d 6f
7s 7p 7d 7f
Begin 7th

16. Warm-Up
The density of a substance is 5.25 g/mL. What is the mass(in kilograms) of 0.75 L of the substance?

17. Warm-Up What elements are the following: 1s22s22p4
1s22s22p63s23p64s23d7
1s22s22p63s23p64s23d104p65s24d105p11

18. Practice Long Hand Electron ConfigurationsCd B P Ba As I Na

19. Review
Write the Long Hand/Expanded electron configuration for the following elements: Sn Ga Y

20. Noble Gas Electron Configuration
Place the following Element using the Noble Gas/short hand electron configuration: Sc I Ru Fr Fe F

21. Practice Problems
Write the Noble Gas Electron Configuration for the following: Tc Zn K I P

22. Orbital diagrams show how electrons fill each sublevel
s has 1 sublevel
p has 3 sublevels
d has 5 sublevels
f has 7 sublevels