2. Orbital Filling Electron Configurations Where do these electrons go?

3. Aufbau Principle Orbitals are filled from lowest energy to highest energy Orbitals closest to the nucleus contain lower energy – They are filled first

4. Orbital Energies Lowest to Highest

5. Orbital Diagrams Shows the distribution of electrons within orbitals Circles/Lines/Boxes are used to represent the different orbitals Arrows are used to represent single electrons

6. Orbital Diagram for Hydrogen 1s Aufbau Principle Orbitals are filled from lowest energy to highest energy

7. Orbital Diagram for Helium 1s Aufbau Principle Orbitals are filled from lowest energy to highest energy

8. Orbital Diagram for Helium 1s Pauli Exclusion Principle Each orbital can only contain two electrons These electrons must be distinguished from one another (“opposite spin”) One arrow up, One arrow down

9. Orbital Diagram for Lithium 1s Aufbau Principle Orbitals are filled from lowest energy to highest energy 2s

10. Orbital Diagram for Boron 1s Aufbau Principle Orbitals are filled from lowest energy to highest energy 2s 2p The first “p” sublevel When the sublevels are drawn, all orbitals within that sublevel must be drawn

11. Orbital Diagram for Carbon 1s Aufbau Principle Orbitals are filled from lowest energy to highest energy 2s 2p When the sublevels are drawn, all orbitals within that sublevel must be drawn

12. Orbital Diagram for Carbon 1s 2s 2p Hund’s Rule Electrons will not pair up within orbitals until each orbital within a sublevel contains at least one electron Electrons distribute “evenly”

13. Orbital Diagram for Neon 1s Aufbau Principle Orbitals are filled from lowest energy to highest energy 2s 2p All orbitals within the highest sublevel level are completely filled

14. Orbital Diagram for Phosphorus 1s Aufbau Principle 2s 2p 3s3p Hund’s Rule

15. Orbital Diagram for Potassium 1s2s2p 3s3p Aufbau Principle Orbitals are filled from lowest energy to highest energy 4s

16. Orbital Diagram for Vanadium 1s2s2p 3s3p Aufbau Principle Orbitals are filled from lowest energy to highest energy 4s3d When the sublevels are drawn, all orbitals within that sublevel must be drawn Hund’s Rule

17. Electron Configurations A short hand way of representing the “location” of electrons around the nucleus Not as much detail as orbital diagrams, but a convenient way of showing patterns for groups of elements on the periodic table

18. Electron Configuration for Hydrogen 1s 1s 1

19. Electron Configuration for Helium 1s 1s 2

20. Electron Configuration for Carbon 1s 2s 2p 1s 2 2s 2 2p 2

21. Electron Configuration for Neon 1s 2s 2p 1s 2 2s 2 2p 6

22. Electron Configuration for Phosphorus 1s 2s 2p 3s3p 1s 2 2s 2 2p 6 3s 2 3p 3

23. Electron Configurations for… Hydrogen Helium Lithium Boron Carbon Neon Sodium Phosphorus Argon Potassium Vanadium Manganese

24. Patterns in Electron Configurations All elements within the same column have the same “ending” for their electron configuration – All end with electrons in the same sublevel, but different principal energy level These elements all belong to the same “family” or “group” They exhibit similar chemical properties – Due to their similar electron configurations, which will be discussed in more detail in later chapters

25. Groups of Elements & Electron Configurations