Electron Configurationsand

Orbital Diagrams

Maximum Number of Electrons In Each SublevelMaximum Number of Electrons In Each Sublevel

Maximum Number Sublevel Number of Orbitals of Electrons

s 1 2

p 3 6

d 5 10

f 7 14

LeMay Jr, Beall, Robblee, Brower, Chemistry Connections to Our Changing World , 1996, page 146

General Rules

Aufbau PrincipleAufbau Principle

– Electrons fill the lowest energy orbitals first.

– “Lazy Tenant Rule”

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2s

3s

4s

5s

6s

7s

1s

2p

3p

4p

5p

6p

3d

4d

5d

6d

4f

5f

1s

2s

2p

3s

3p

4s

4p

3d

4d5s

5p6s

7s

6p

6d

4f

5f

5d

En

erg

y

Order in which subshells are filled with electrons

1s

2s

3s

4s

5s

6s

7s

2p

3p

4p

5p

6p

3d

4d

5d

6d

4f

5f

1s 2s 2p 3s 3p 4s 3d 4p 5s 4d … 2 2 6 2 6 2 10 6 2 10

Energy Level Diagram of a Many-Electron Atom

ArbitraryEnergy Scale

18

18

32

8

8

2

1s

2s 2p

3s 3p

4s 4p 3d

5s 5p 4d

6s 6p 5d 4f

NUCLEUS

O’Connor, Davis, MacNab, McClellan, CHEMISTRY Experiments and Principles 1982, page 177

General Rules

• Pauli Exclusion PrinciplePauli Exclusion Principle

– Each orbital can hold TWO electrons with

opposite spins.

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Wolfgang Pauli

RIGHTWRONG

General Rules

• Hund’s RuleHund’s Rule

– Within a sublevel, place one electron per orbital before pairing them.

– “Empty Bus Seat Rule”

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Filling Rules for Electron Orbitals

Aufbau Principle: Electrons are added one at a time to the lowest energy orbitals available until all the electrons of the atom have been accounted for.

Pauli Exclusion Principle: An orbital can hold a maximum of two electrons.To occupy the same orbital, two electrons must spin in opposite directions.

Hund’s Rule: Electrons occupy equal-energy orbitals so that a maximum number of unpaired electrons results.

*Aufbau is German for “building up”

O

8e-

• Orbital Diagram

• Electron Configuration

1s1s22 2s2s22 2p2p44

Notation

1s 2s 2p

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O15.9994

8

Orbital Filling

Element 1s 2s 2px 2py 2pz 3s Configuration

Electron ConfigurationsElectron

H

He

Li

C

N

O

F

Ne

Na

1s1

1s22s22p63s1

1s22s22p6

1s22s22p5

1s22s22p4

1s22s22p3

1s22s22p2

1s22s1

1s2

Energy Level Diagram

Arb

itrar

y E

nerg

y S

cale

1s

2s 2p

3s 3p

4s 4p 3d

5s 5p 4d

6s 6p 5d 4f

NUCLEUS

Electron Configuration

CLICK ON ELEMENT TO FILL IN CHARTS

N

N = 1s22s22p3

Bohr Model

Nitrogen

Hund’s Rule “maximum number of unpaired

orbitals”.

H He Li C N Al Ar F Fe La

Energy Level Diagram

Arb

itrar

y E

nerg

y S

cale

1s

2s 2p

3s 3p

4s 4p 3d

5s 5p 4d

6s 6p 5d 4f

NUCLEUS

CLICK ON ELEMENT TO FILL IN CHARTS

Fe = 1s22s22p63s23p64s23d6

N

H He Li C N Al Ar F Fe La

Bohr Model

Iron

Electron Configuration

sp

d (n-1)

f (n-2) 67

Periodic Patterns

11ss

22ss

33ss

44ss

55ss

66ss

77ss

33dd

44dd

55dd

66dd

11ss

22pp

33pp

44pp

55pp

66pp

77pp

44ff

55ff

1234567

s-block1st Period

1s11st column of s-block

Periodic Patterns

• Example - Hydrogen

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