Ch 4 Electrons in Atoms IV Electron Configuration

Ch. 4 - Electrons in Atoms IV. Electron Configuration (p. 105 - 116, 128 - 139)

A. General Rules z. Pauli Exclusion Principle y. Each orbital can hold TWO electrons with opposite spins. y“opposite sex rule”

A. General Rules z. Aufbau Principle y. Electrons fill the lowest energy orbitals first. y“Lazy Tenant Rule”

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

B. Notation z. Orbital Diagram O 8 e- 1 s 2 s z. Electron Configuration 2 2 4 1 s 2 s 2 p 2 p

B. Notation z. Longhand Configuration S 16 e 6 2 2 2 1 s 2 s 2 p 3 s Core Electrons Valence Electrons z. Shorthand Configuration S 16 e 4 3 p 2 4 [Ne] 3 s 3 p

C. Periodic Patterns s p 1 2 3 4 5 6 7 f (n-2) d (n-1) 6 7 © 1998 by Harcourt Brace & Company

C. Periodic Patterns z. Period # yenergy level (subtract for d & f) z. A/B Group # ytotal # of valence ez. Column within sublevel block y# of e- in sublevel

C. Periodic Patterns z. Example - Hydrogen 1 1 s 1 st Period 1 st column of s-block

C. Periodic Patterns z. Shorthand Configuration y. Core e-: Go up one row and over to the Noble Gas. y. Valence e-: On the next row, fill in the # of e- in each sublevel.

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

D. Stability z. Full energy level z. Full sublevel (s, p, d, f) z. Half-full sublevel

D. Stability z. Electron Configuration Exceptions y. Copper EXPECT: [Ar] 4 s 2 3 d 9 ACTUALLY: [Ar] 4 s 1 3 d 10 y. Copper gains stability with a full d-sublevel.

D. Stability z. Electron Configuration Exceptions y. Chromium EXPECT: [Ar] 4 s 2 3 d 4 ACTUALLY: [Ar] 4 s 1 3 d 5 y. Chromium gains stability with a half-full d-sublevel.

D. Stability z. Ion Formation y. Atoms gain or lose electrons to become more stable. y. Isoelectronic with the Noble Gases.

D. Stability z. Ion Electron Configuration y. Write the e- config for the closest Noble Gas y. EX: Oxygen ion O 2 - Ne 2 O 10 e [He] 2 2 s 6 2 p