Ch. 5- Electrons and atoms (cont.)
General Rules zWe have 3 general rules that we follow when determining electron configuration yAufbau Principal yPauli Exclusion Principal yHund’s Rule
A. General Rules zAufbau Principle yElectrons fill the lowest energy orbitals first. y“Lazy Tenant Rule”
A. General Rules zPauli Exclusion Principle yEach orbital can hold TWO electrons with opposite spins.
RIGHT WRONG A. General Rules zHund’s Rule yWithin a sublevel, place one e - per orbital before pairing them. y“Empty Bus Seat Rule”
O 8e - zOrbital Diagram zElectron Configuration 1s 2 2s 2 2p 4 B. Notation 1s 2s 2p
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
© 1998 by Harcourt Brace & Company s p d (n-1) f (n-2) C. Periodic Patterns
Remember the AufBau Diagram?
C. Periodic Patterns zPeriod # yenergy level (subtract for d & f) zA/B Group # ytotal # of valence e - zColumn within sublevel block y# of e - in sublevel
s-block1st Period 1s 1 1st column of s-block C. Periodic Patterns zExample - Hydrogen
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.
[Ar]4s 2 3d 10 4p 2 C. Periodic Patterns zExample - Germanium
zFull energy level zFull sublevel (s, p, d, f) zHalf-full sublevel D. Stability
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
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
zIon Formation yAtoms gain or lose electrons to become more stable. yIsoelectronic with the Noble Gases.
O 2- 10e - [He] 2s 2 2p 6 D. Stability zIon Electron Configuration yWrite the e - config for the closest Noble Gas yEX: Oxygen ion O 2- Ne