1. IV. ELECTRON CONFIGURATION (P. 135-141) Ch. 5 - Electrons in Atoms y C. JOHANNESSON

2. A. GENERAL RULES Pauli Exclusion Principle  Each orbital can hold TWO electrons with opposite spins. y C. JOHANNESSON

3. A. GENERAL RULES Aufbau Principle  Electrons fill the lowest energy orbitals first.  Electrons are lazy  P. 135 y C. JOHANNESSON

4. A. GENERAL RULES Hund’s Rule  Within a sublevel, place one e - per orbital before pairing them.  “Empty Bus Seat Rule” y C. JOHANNESSON RIGHT WRONG

5. B. NOTATION Orbital Diagram y C. JOHANNESSON O 8e - zElectron Configuration 1s 2 2s 2 2p 4 1s 2s 2p

6. y C. JOHANNESSON      1s 2s 2p 3s 3p    4s 3d 4p    5s 4d 5p

7. y C. JOHANNESSON

8. C. PERIODIC PATTERNS y C. JOHANNESSON © 1998 by Harcourt Brace & Company s p d (n-1) f (n-2) 12345671234567 6767

9. y C. JOHANNESSON

10. C. PERIODIC PATTERNS Period #  energy level (subtract for d & f) A/B Group #  total # of valence e - Column within sublevel block  # of e - in sublevel y C. JOHANNESSON

11. C. PERIODIC PATTERNS Example - Hydrogen y C. JOHANNESSON s-block1st Period 1s 1 1st column of s-block

12. C. PERIODIC PATTERNS Shorthand Configuration (Noble Gas Notation)  Core e - : Go up one row and over to the Noble Gas.  Valence e - : On the next row, fill in the # of e - in each sublevel. y C. JOHANNESSON

13. C. PERIODIC PATTERNS Example - Germanium y C. JOHANNESSON [Ar]4s 2 3d 10 4p 2

14. B. NOTATION Longhand Configuration y C. JOHANNESSON zShorthand Configuration (Noble Gas Notation) S 16e - Valence Electrons Core Electrons S16e - [Ne] 3s 2 3p 4 1s 2 2s 2 2p 6 3s 2 3p 4

15. D. STABILITY Full energy level y C. JOHANNESSON zFull sublevel (s, p, d, f) zHalf-full sublevel

16. D. STABILITY Electron Configuration Exceptions y C. JOHANNESSON yCopper EXPECT :[Ar] 4s 2 3d 9 ACTUALLY :[Ar] 4s 1 3d 10 yCopper gains stability with a full d-sublevel.

17. D. STABILITY Electron Configuration Exceptions y C. JOHANNESSON yChromium EXPECT :[Ar] 4s 2 3d 4 ACTUALLY :[Ar] 4s 1 3d 5 yChromium gains stability with a half- full d-sublevel.

18. D. STABILITY Ion Formation  Atoms gain or lose electrons to become more stable.  Isoelectronic with the Noble Gases. y C. JOHANNESSON

19. D. STABILITY Ion Electron Configuration  Write the e - config for the closest Noble Gas  EX: Oxygen ion  O 2-  Ne y C. JOHANNESSON O 2- 10e - [He] 2s 2 2p 6