1. Electron Configuration
Mapping the electrons

2. Electron Configuration
The way electrons are arranged around the nucleus.

3. Quantum Mechanical Model
1920’s
Werner Heisenberg (Uncertainty Principle)
Erwin Schrodinger (mathematical equations using probability, quantum numbers)

4. Heisenberg uncertainty principle
It is impossible to determine simultaneously both the position and velocity of an electron or any other particle with any great degree of accuracy or certainty.

5. Erwin Schrodinger
Formulated equation that describes behavior and energies of subatomic particles.
Leads to Quantum Mechanics: we cannot pinpoint an electron in an atom but we can define the region where electrons can be in a particular time……… called a Probability map….a 3-dimensional area in space called an ORBITAL

6. Principal Quantum Number, n
Indicates main energy levels
n = 1, 2, 3, 4…
Each main energy level has sub-levels

7. Energy Sublevels
s p d f

8. The principle quantum number, n, determines the number of sublevels within the principle energy level.

9. Orbital
The space where there is a high probability that it is occupied by a pair of electrons.
Orbitals are solutions of Schrodinger’s equations.

10. Orbitals

11. Orbitals in Sublevels Sublevel # Orbitals # electrons s 1 2 p 3 6d f

12. Three rules are used to build the electron configuration:
Aufbau principle
Pauli Exclusion Principle
Hund’s Rule

13. Aufbau Principle
Electrons occupy orbitals of lower energy first.

14. Orbital Diagram

15. Filling Order diagram

16. -Pauli Exclusion Principle (Wolfgang Pauli, Austria, 1900-1958) -Electron Spin Quantum Number
An orbital can hold only two electrons and they must have opposite spin.

17. Hund’s Rule
In a set of orbitals, the electrons will fill the orbitals in a way that would give the maximum number of parallel spins (maximum number of unpaired electrons).
Analogy: Students could fill each seat of a school bus, one person at a time, before doubling up.

18. Orbital Diagram for Hydrogen

19. Orbital Diagram for Helium

20. Orbital Diagram for Lithium

21. Orbital Diagram for Beryllium

22. Orbital Diagram for Boron

23. Orbital Diagram for Carbon

24. Orbital Diagram for Nitrogen

25. Orbital Diagram for Fluorine

26. Standard Notation of Fluorine
Number of electrons
in the sub level 2,2,5
1s2 2s2 2p5
Main Energy Level Numbers 1, 2, 2
Sublevels

27. Sources