FACT:

1. FACT: Chemical reactions happen because electrons are shared or transferred from one substance to another

2. Key Words:(from Physical Science) • Energy Level • Valence electron

3. MAX NUMBER OF ELECTONS IN AN ENERGY LEVEL

4. Quantum-Mechanical Model A model of the atom that explains electrons as a wave with quantized energy. (The best model we know of yet.)

5. There are 4 Quantum #s and those #s are used to describe EXACTLY where an electron is at any given time.

6. This is a lot like being able to use four “places” to describe EXACTLY where you can be found right now.

7. 1st Quantum # Specifies the energy level that the electron is on (Principle Quantum #)

8. 2nd Quantum # Specifies the shape of the sub-energy level (s, p, d, or f)

9. s and p Orbitals

10. ORBITAL Space occupied by a pair of electrons

11. Four Sub-Energy Levels

12. Sub-Energy Levels

13. 3rd Quantum # Specifies the orientation of an orbital in space (x,y,z)

14. s and p Orbitals

15. 4th Quantum # Spin of an electron on its own axis (or )

16. Quantum Review 1st Q#: Energy Level 2nd Q#: Shape of sub energy level 3rd Q#: Orientation of Orbital 4th Q#: Spin of e-

17. So why do electrons fill in like they do? i.e. why is K’s last electron in the 4th NRG level?

18. 2 Factors Influencing Electron Placement 1. Energy Level - Closer to nucleus first2. Sub-energy level (shape) - spdf

19. Electron Configuration A detailed way of showing the order in which electrons fill in around the nucleus

20. Pauli Exclusion Principle No 2 electrons can have the same set of 4 quantum numbers

21. Electron Configuration Symbols # of e- in sub-energy level 5f3 Energy Level Sub-Energy Level

22. Bohr Models vs. e- Configs K 4s1 K: 1s2 2s2 3s2 3p6 2p6

23. Electron Configuration PT

24. 1s1 Write the e-config for: He: 1s2 Li: 1s22s1 H: K: 1s22s22p63s23p64s1

25. Again…Why are we concerned so much about electrons?

26. So do we really need to know about all of the electrons?

27. K: 1s22s22p63s23p64s1 Noble Gas Shortcut [Ar] 4s1 K: So what is different?

28. Steps for writing NGSC Write the noble gas preceding the desired element [in brackets] Carry on as usual

29. e- configs with the NGSC represent which electrons?

30. Arrow-Orbital Diagrams Energy 3d 4s 3p 3s 2p 2s 1s

31. Lewis Electron Dot Diagrams An easy way to represent the # of valence electrons

32. Valence Electrons Electrons in the outermost energy level (involved in chemical reactions)

33. Steps for writing electron dot diagrams Write the element’s symbol Write out e- config Count # of valence e-s (1-8) Place same # of dots as e- around symbol

34. Order to fill in an e-dot 3 6 4 1 Bm 7 2 5 8

35. What’s up? Bm 1 Who do 1 and 2 represent? 2 Why do 1 and 2 fill in on the same side?

36. What’s up? 3 6 Bm 4 Who do 3-8 represent? 7 5 8 Why do 3,4,5 and 6,7,8 fill in on different sides?

37. What’s up? 3 6 Bm 4 1 Why will you never have more than eight dots? 7 2 5 8

38. Examples of Lewis Electron Dots

39. What is different between the dot diagrams below and the ones that we’ve been doing? Our way accounts for Quantum #s, this way doesn’t!

40. Equation to calculate Max # of e- : 2n2 Where n is any energy level