1. Electron Configuration

2. Electron Configuration
electron configuration is the distribution of electrons of an atom in atomic or molecular orbitals.
For example, the electron configuration of the neon atom is 1s2 2s2 2p6.

3. The Quantum Mechanical Model
based on quantum theory, which says matter also has properties associated with waves.
This theory states it’s impossible to know the exact position of each electron at the same time.
This is known as the Uncertainty Principle.

4. The Quantum Mechanical Model
Each energy level contains a definite number of orbitals of specific types
The different types being called subshells
Each subshell contains a specific number of electrons

5. Quantum Mechanical Based on Probability
This model determines where there is likely to be an electron. So, this model is based on probability (MATH!) rather than certainty.

6. Orbitals

7. Orbitals
-Each energy sublevel corresponds to an orbital of a different shape, which describes where the electron is likely to be found. (s, p, and d orbitals)
-Bohr used orbits; Schrodinger used orbitals

8. Energy Level 1
s Orbital
(1 orbital)

9. Energy Level 2 2 subshells: s and p s orbital (1 orbital)
p subshell (3 orbitals)

10. Energy Level 3 3 subshells: s, p, and d s orbital (1 orbital)
p subshell (3 orbitals)
d subshell (5 orbitals)

11. Energy Level 4 4 subshells: s, p, d, and f s orbital (1 orbital)
p subshell (3 orbitals)
d subshell (5 orbitals)
f subshell (7 orbitals)

13. The numbers and kinds of atomic orbitals depend on the energy sublevel.

14. The number of electrons allowed in each of the first four energy levels are shown here.

15. Electron Arrangement in Atoms
If this rock were to tumble over, it would end up at a lower height. It would have less energy than before, but its position would be more stable.
Electrons are more stable in lower energy levels

16. Electron Configuration Rules!
Three rules
the aufbau principle,
the Pauli exclusion principle, and
Hund’s rule—tell you how to find the electron configurations of atoms.

17. Aufbau Principle The electrons fill the lowest energy level first
Each orbital can hold a maximum of two electrons
If there are 2 or more vacant orbitals of the same energy level, each orbital accepts one electron before the orbitals in the subshell begin filling the second electron. (Hund’s rule)
-this happens in the 3 p orbitals of the p subshell

18. Hund’s Rule
Hund’s rule states that electrons occupy orbitals of the same energy in a way that makes the number of electrons with the same spin direction as large as possible.

19. this happens in the 3 p orbitals of the p subshell
Hund’s Rule
3) If there are 2 or more vacant orbitals of the same energy level, each orbital accepts one electron before the orbitals in the subshell begin filling the second electron. (Hund’s rule)
this happens in the 3 p orbitals of the p subshell

20. Aufbau Principal Simple Version
According to the aufbau principle, electrons occupy the orbitals of lowest energy first. In the aufbau diagram below, each box represents an atomic orbital.

21. Pauli Exclusion Principle
atomic orbital have at most two electrons.
To occupy the same orbital, two electrons must have opposite spins; that is, the electron spins must be paired.

23. Write electron configurations for the first 10 elements.
Hydrogen
Helium
Lithium
Beryllium
Boron
Carbon
Nitrogen
Oxygen
Fluorine
Neon

24. Electron Configurations Practice
Write the electron configurations for Al Cl

25. Electron Configurations Practice
Write the electron configurations for Al
Al 1s2 2s2 2p6 3s2 3p1 Cl
Cl 1s2 2s2 p6 3s2 p5

26. Look in Your Book!
Red book pg. 28