IV. Electron Configuration (p. 105 - 116, 128 - 139) Ch. 5 - Electrons in Atoms IV. Electron Configuration (p. 105 - 116, 128 - 139) C. Johannesson

A. General Rules Pauli Exclusion Principle Each orbital can hold TWO electrons with opposite spins. C. Johannesson

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

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

1s2 2s2 2p4 O B. Notation 1s 2s 2p 8e- Orbital Diagram Electron Configuration 1s2 2s2 2p4 C. Johannesson

S 16e- 1s2 2s2 2p6 3s2 3p4 S 16e- [Ne] 3s2 3p4 B. Notation Longhand Configuration S 16e- 1s2 2s2 2p6 3s2 3p4 Core Electrons Valence Electrons Shorthand Configuration (Noble-gas notation) S 16e- [Ne] 3s2 3p4 C. Johannesson

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

1s1 C. Periodic Patterns 1st column of s-block 1st Period s-block Example - Hydrogen 1s1 1st column of s-block 1st Period s-block C. Johannesson

C. Periodic Patterns p s d (n-1) f (n-2) Shorthand Configuration 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. s d (n-1) f (n-2) p C. Johannesson

[Ar] 4s2 3d10 4p2 C. Periodic Patterns Example - Germanium C. Johannesson

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

D. Stability Electron Configuration Exceptions Copper EXPECT: [Ar] 4s2 3d9 ACTUALLY: [Ar] 4s1 3d10 Copper gains stability with a full d-sublevel. C. Johannesson

D. Stability Electron Configuration Exceptions Chromium EXPECT: [Ar] 4s2 3d4 ACTUALLY: [Ar] 4s1 3d5 Chromium gains stability with a half-full d-sublevel. C. Johannesson

D. Stability 1+ 2+ 3+ NA 3- 2- 1- Ion Formation Atoms gain or lose electrons to become more stable. Isoelectronic with the Noble Gases. 1+ 2+ 3+ NA 3- 2- 1- C. Johannesson

O2- 10e- [He] 2s2 2p6 D. Stability Ion Electron Configuration Write the e- config for the closest Noble Gas EX: Oxygen ion  O2-  Ne O2- 10e- [He] 2s2 2p6 C. Johannesson

Electron Dot Structure C. Johannesson

Electron Dot Structure C. Johannesson

B. Quantum Mechanics Orbital (“electron cloud”) Region in space where there is 90% probability of finding an e- Orbital C. Johannesson

C. Quantum Numbers Four Quantum Numbers: Specify the “address” of each electron in an atom UPPER LEVEL C. Johannesson

C. Quantum Numbers 1. Principal Quantum Number ( n ) Energy level Size of the orbital n2 = # of orbitals in the energy level C. Johannesson

C. Quantum Numbers f d s p 2. Angular Momentum Quantum # ( l ) Energy sublevel Shape of the orbital f d s p C. Johannesson

C. Quantum Numbers 3. Magnetic Quantum Number ( ml ) Orientation of orbital Specifies the exact orbital within each sublevel C. Johannesson

C. Quantum Numbers px py pz C. Johannesson

C. Quantum Numbers 2s 2px 2py 2pz Orbitals combine to form a spherical shape. 2s 2pz 2py 2px C. Johannesson

C. Quantum Numbers 4. Spin Quantum Number ( ms ) Electron spin  +½ or -½ An orbital can hold 2 electrons that spin in opposite directions. C. Johannesson

C. Quantum Numbers Pauli Exclusion Principle No two electrons in an atom can have the same 4 quantum numbers. Each e- has a unique “address”: 1. Principal #  2. Ang. Mom. #  3. Magnetic #  4. Spin #  energy level sublevel (s,p,d,f) orbital electron C. Johannesson

Bohr Models C. Johannesson

Bohr Models C. Johannesson

Bohr Models C. Johannesson

Classwork #24 on page 160 #29 on page 162 (don’t draw the orbital diagrams) #85 on 167 #87 on page 168 C. Johannesson

Classwork ELECTRON DOT CONFIGURATION Page 162 do #33 Page 168 do #90, 92, and 93 Page 979 do #5, 6, 7, 8, 9 (b, c, d) for Chapter 5 C. Johannesson