1. Electron Configuration Honor’s Chemistry Mr. Bostrom

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

3. Quantum Mechanical Model • 1920’s • Werner Heisenberg (Uncertainty Principle) • Louis de Broglie (electron has wave properties) • Erwin Schrodinger (mathematical equations using probability, quantum numbers)

4. Principal Quantum Number, n • Indicates main energy levels n = 1, 2, 3, 4… To calculate the total # of electrons per principal energy level 2n2 • Each main energy level has sub-levels

5. Energy Sublevels s p d f

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

7. 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.

8. Orbital Quantum Number, ℓ(Angular Momentum Quantum Number) • Indicates shape of orbital sublevels • ℓ = n-1 ℓ sublevel shape 0 s spherical 1 p dumbell 2 d cloverleaf 3 f see picture

9. Orbital Shapes • s - orbital

10. Orbital Shapes • p - orbitals

11. Orbital Shapes • d - orbitals

12. Orbital Shapes • F - orbitals

13. Orbitals in Sublevels Sublevel# Orbitals# electrons s 1 2 p 3 6 d 5 10 f 7 14

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

15. Aufbau Principle • Electrons occupy orbitals of lower energy first.

16. Aufbau Diagram

17. -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. • Electron Spin Quantum Number (ms): +1/2, -1/2

18. 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.

19. Aufbau Diagram for Hydrogen

20. Aufbau Diagram for Helium

21. Aufbau Diagram for Lithium

22. Aufbau Diagram for Beryllium

23. Aufbau Diagram for Boron

24. Aufbau Diagram for Carbon

25. Aufbau Diagram for Nitrogen

26. Notations of Electron Configurations • Standard • Shorthand

27. Aufbau Diagram for Fluorine

28. Standard Notation of Fluorine Number of electrons in the sub level 2,2,5 1s22s22p5 Main Energy Level Numbers 1, 2, 2 Sublevels Note: This may not be in the same order as in the Aufbau Pr

29. Shorthand or Core Notation • Use the last noble gas that is located in the periodic table right before the element. • Write the symbol of the noble gas in brackets. • Write the remaining configuration after the brackets. • Ex: Fluorine: [He] 2s2 2p5

30. Blocks in the Periodic Table

31. How can I remember which energy levels come first

32. Let’s Compare