1. IV. Electron Configuration Ch. 4 - Electrons in Atoms

2. Electron Configuration zThe arrangement of electrons in an atom. zA distinct configuration exists for each atom.

3. Electron Configuration zLike all systems in nature, electrons in atoms tend to assume arrangements that have the lowest possible energies. z Ground State: the lowest energy arrangement of the electrons.

4. A. General Rules zPauli Exclusion Principle yEach orbital can hold TWO electrons with opposite spins.

5. A. General Rules zAufbau Principle yElectrons fill the lowest energy orbitals first. y“Lazy Tenant Rule”

6. RIGHT WRONG A. General Rules zHund’s Rule yWithin a sublevel, place one e - per orbital before pairing them. y“Empty Bus Seat Rule”

7. O 8e - zOrbital Diagram zElectron Configuration 1s 2 2s 2 2p 4 B. Notation 1s 2s 2p

8. zShorthand Configuration S 16e - Valence Electrons Core Electrons S16e - [Ne] 3s 2 3p 4 1s 2 2s 2 2p 6 3s 2 3p 4 B. Notation zLonghand Configuration

9. © 1998 by Harcourt Brace & Company s p d (n-1) f (n-2) 12345671234567 6767 C. Periodic Patterns

10. zPeriod # yenergy level (subtract for d & f) zA/B Group # ytotal # of valence e - zColumn within sublevel block y# of e - in sublevel

11. s-block1st Period 1s 1 1st column of s-block C. Periodic Patterns zExample - Hydrogen

12. C. Periodic Patterns zShorthand Configuration yCore e - : Go up one row and over to the Noble Gas. yValence e - : On the next row, fill in the # of e - in each sublevel.

13. [Ar]4s 2 3d 10 4p 2 C. Periodic Patterns zExample - Germanium

14. zFull energy level zFull sublevel (s, p, d, f) zHalf-full sublevel D. Stability

15. zElectron Configuration Exceptions yCopper EXPECT :[Ar] 4s 2 3d 9 ACTUALLY :[Ar] 4s 1 3d 10 yCopper gains stability with a full d-sublevel. D. Stability

16. zElectron Configuration Exceptions yChromium EXPECT :[Ar] 4s 2 3d 4 ACTUALLY :[Ar] 4s 1 3d 5 yChromium gains stability with a half-full d-sublevel. D. Stability