1. Section 5.2 Electron Arrangement in Atoms

2. We’ve looked at it this way

3. Electron Configurations Follow three rules… 1.The Aufbau principle 2.The Pauli Exclusion Principle 3.Hund’s Rule

4. The Aufbau Principle Electrons occupy the orbitals of lowest energy first

5. The Pauli Exclusion Principle No two electrons in an atom can have identical quantum numbers. Orbital Notation

6. Hund’s Rule When an electron is added to sublevel, always occupy empty orbital and only pair when necessary.

8. Hund’s Rule or Seats on the Bus

9. Orbital Notation

10. Electron Configuration for Group 1 H1s 1 Li1s 2 2s 1 Na 1s 2 2s 2 2p 6 3s 1 K 1s 2 2s 2 2p 6 3s 2 3p 6 4s 1 Rb1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 6 5s 1 Cs 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 6 5s 2 4d 10 5p 6 6s 1 Fr 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 6 5s 2 4d 10 5p 6 6s 2 4f 14 5d 10 6p 6 7s 1

11. Electron Configuration for Group 18 He1s 2 Ne1s 2 2s 2 2p 6 Ar 1s 2 2s 2 2p 6 3s 2 3p 6 Kr 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 6 Xe1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 6 5s 2 4d 10 5p 6 Rn 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 6 5s 2 4d 10 5p 6 6s 2 4f 14 5d 10 6p 6

12. Noble Gas Configuration He1s 2 Ne[1s 2 ] 2s 2 2p 6 Noble Gas Configuration: Ne [He] 2s 2 2p 6 Na [1s 2 2s 2 2p 6 ] 3s 1 Noble Gas Configuration:Na [Ne] 3s 1

14. Noble Gas Notation Orbital Notation for U Use noble gas notation:

15. Exceptions to Remember Orbital Notation for Cr: Orbital Notation for Cu:

16. Exceptions to Remember 29 Cu 47 Ag 79 Au

17. Exceptions to Remember 24 Cr 42 Mo

18. Electron Dot Notation Only the highest energy level electrons are drawn. (s & p)

19. Electron Dot Notation