ELECTRONS AND THEIR LOCATION

1. ELECTRONS AND THEIR LOCATION ELECTRON ADDRESSES

2. RULES TO REMEMBER • HEISENBERG UNCERTAINTY PRINCIPLE –Cannot know the exact location of an electron. Fundamentally impossible to know both the location and momentum/velocity of an electron at the same time. • The quantum mechanical model merely suggests the probability of the electron location. • No circular orbits – Sorry Bohr! • Instead: orbitals - the 3-dimensional region is which there is a high probability of finding an electron in an atom

3. Aufbau Principle • Electrons fill the lowest possible energy level. • Energy levels correspond to period number on the Periodic Table. • How many energy levels are there?

4. orbitals • Textbook definition: the 3-dimensional region is which there is a high probability of finding an electron in an atom • s on page 371 • p on page 372 • d on page 374

5. Pauli Exclusion Principle • No more than two (2) electrons in an orbital.

6. Hund’s Rule(s) • Orbitals of equal energy must fill singly before doubling. • (ex. all d’s must fill with 1 electron each before the second electron can fill in – like dealing cards) • All electrons in singly occupied orbitals have the same spin direction • Pairs of electrons in the same orbital have opposite spin.

7. QUANTUM NUMBERS • Describe the electron’s “address” • 1stQuantum is the principle quantum – describes the energy level, or period. • 2nd Quantum describes the shape of the orbitals. s,p,d,f • 3rd Quantum describes the orientation of the orbital • 4th Quantum describes the spin of the electron

13. What do you think the 5th energy level looks like? • The pattern stops – it looks like the 4th energy level • What about 6 & 7?

14. Quick Quiz • A. How many electrons can the p orbitals hold if filled? • B. How many kinds of orbitals are in the 4th energy level? • C. What are the orbitals of the 2nd energy level? • D. How many f orbitals are there? • E. How many electrons can any one orbital hold? • F. At most, how many electrons in the 2nd energy level?

15. Orbital Diagrams or Orbital Configurations • Use boxes and arrows to represent electrons in various energy levels. • Boxes must be labeled with regard to energy level and orbitals.

16. H orbital configuration 1s

17. H He orbital configuration 1s 1s

18. H He Li orbital configuration 1s 1s 2s 1s

19. H He Li Be orbital configuration 1s 1s 2s 1s 1s 2s

20. B C orbital configuration 1s 2s 2p 1s 2s 2p

21. N orbital configuration 1s 2s 2p

22. Practice • Draw orbital diagrams for elements # 4,6,9,15, and 26

23. Lewis Dot Structures • Element symbol represents atom nucleus and inner electrons. • Dots around the symbol represent valence (outermost energy level) electrons.

24. Lewis dot structure 1 Symbol

25. Lewis dot structure 1 2 Symbol

26. Lewis dot structure 1 2 3 Symbol

27. Lewis dot structure 1 2 3 Symbol 4

28. Lewis dot structure 1 2 3 5 Symbol 4

29. Lewis dot structure 1 2 5 3 Symbol 6 4

30. Lewis dot structure 1 2 5 3 Symbol 6 4 7

31. Lewis dot structure 1 2 3 5 Symbol 6 8 4 7

32. practice • Draw Lewis Dot structures for elements 1-11

33. Bohr Models • Use concentric circles to represent energy levels and the number of electrons in each.

34. Bohr model H 1-

35. Bohr model Li 2- 1-

36. Bohr model Ne 2- 8-

37. Bohr model S 2- 8- 6-

38. Bohr model K 2- 1- 8- 8-

39. Practice • Draw Bohr models for elements # 2, 3, 5, 9, and 16