Quantum NumbersQuantum Numbers

1. Principal #1. Principal # 2. Ang. Mom. #2. Ang. Mom. # 3. Magnetic #3. Magnetic # 4. Spin #4. Spin #

energy levelenergy level

sublevel (s,p,d,f)sublevel (s,p,d,f)

orbitalorbital

electronelectron

Pauli Exclusion PrinciplePauli Exclusion Principle

– No two electrons in an atom can have the No two electrons in an atom can have the same 4 quantum numbers.same 4 quantum numbers.

– Each eEach e-- has a unique “address”: has a unique “address”:

General RulesGeneral Rules

Aufbau PrincipleAufbau Principle

– Electrons fill the Electrons fill the lowest energy lowest energy orbitals first.orbitals first.

– ““Lazy Student Lazy Student Rule”Rule”

General RulesGeneral Rules

The Diagonal RuleThe Diagonal Rule

2p3p4p5p6p7p

3d4d5d6d

4f5f

2s3s4s5s6s7s

1s

8s

WRONGRIGHT

General RulesGeneral Rules

Hund’s RuleHund’s Rule

– Within a sublevel, place one eWithin a sublevel, place one e-- per orbital per orbital before pairing them.before pairing them.

– ““Empty Bus Seat Rule”Empty Bus Seat Rule”

O

8e-

Orbital Diagram / Box & Arrow DiagramOrbital Diagram / Box & Arrow Diagram

Electron Configuration / SPDF NotationElectron Configuration / SPDF Notation

1s2 2s2 2p4

NotationNotation

1s 2s 2p

Shorthand ConfigurationShorthand Configuration

S 16e-

Valence Electrons

Core Electrons

S 16e- [Ne] 3s2 3p4

1s2 2s2 2p6 3s2 3p4

NotationNotation

Longhand ConfigurationLonghand Configuration

© 1998 by Harcourt Brace & Company

sp

d (n-1)

f (n-2)

1234567

67

Periodic PatternsPeriodic Patterns

Periodic PatternsPeriodic Patterns

Period #Period #– energy level (subtract for d & f)energy level (subtract for d & f)

A/B Group # A/B Group # – total # of valence etotal # of valence e--

Column within sublevel blockColumn within sublevel block– # of e# of e-- in sublevel in sublevel

s-block

1st Period

1s11st column of s-block

Periodic PatternsPeriodic Patterns

Example - Example - HydrogenHydrogen

1

2

3

4

5

6

7

Periodic PatternsPeriodic Patterns

Shorthand ConfigurationShorthand Configuration– Core eCore e--:: Go up one row and over to the Noble Go up one row and over to the Noble

Gas.Gas.– Valence eValence e--:: On the next row, fill in the # of e On the next row, fill in the # of e --

in each sublevel.in each sublevel.

[Ar] 4s2 3d10 4p2

Periodic PatternsPeriodic Patterns

Example - Example - GermaniumGermanium

Full energy levelFull energy level

1

2

3

4 5

6

7

Full sublevel (s, p, d, f)Full sublevel (s, p, d, f)

Half-full sublevelHalf-full sublevel

StabilityStability

Electron Configuration ExceptionsElectron Configuration Exceptions– CopperCopper

EXPECTEXPECT:: [Ar] 4s[Ar] 4s22 3d 3d99

ACTUALLYACTUALLY:: [Ar] 4s[Ar] 4s11 3d 3d1010

– Copper gains Copper gains stabilitystability with a full with a full d-sublevel.d-sublevel.

StabilityStability

Electron Configuration ExceptionsElectron Configuration Exceptions– ChromiumChromium

EXPECTEXPECT:: [Ar] 4s[Ar] 4s22 3d 3d44

ACTUALLYACTUALLY:: [Ar] 4s[Ar] 4s11 3d 3d55

– Chromium gains Chromium gains stabilitystability with a half-full d- with a half-full d-sublevel.sublevel.

StabilityStability

StabilityStability

Ion FormationIon Formation– Atoms gain or lose electrons to become more stable.Atoms gain or lose electrons to become more stable.– Isoelectronic with the Noble Gases.Isoelectronic with the Noble Gases.

OO2- 2- 10e10e- - [He] 2s[He] 2s22 2p 2p66

StabilityStability

Ion Electron ConfigurationIon Electron Configuration

– Write the eWrite the e-- config for the closest Noble Gas config for the closest Noble Gas

– EXEX: Oxygen ion : Oxygen ion O O2-2- Ne Ne