unit 5: light and electron...

C H E M I S T R Y

2 0 1 4 - 1 5

M R . R O N G

Unit 5: Light and Electron Configuration

Historical Models of the Atom

Dalton Thomson Rutherford Bohr

What do you notice about where the electrons are?

Bohr Model

How many electrons can fit in a level?

Energy levels Maximum # of Electrons

1 2

2 8

3 18

Lewis Structures

Hog Hilton

Congratulations, managers of the Hog Hilton! You’ve successfully booked rooms for all our guests!

Now let’s learn how this relates to how electrons fit within the atom.

States of Electrons

Normally, an electron is at the lowest state of energy possible, the ground state.

If energy is added, an electron can move an energy level and is then considered to be in an excited state.

States of Electrons

Since this is unstable, when the electron falls back down, it emits energy in the form of light.

Hog Hilton

Pauli Exclusion Principle:

No 2 electrons can have exactly the same “energy address” (same 4 quantum numbers).

To be in the same orbital, they must have opposite spins.

Hog Hilton

Aufbau Principle:

Fill lower sublevels before moving up electrons to higher sublevels

Hog Hilton

Hund’s Rule:

Electrons are placed in individual orbitals before they are paired up.

Maximum Number of Electrons In Each Sublevel Maximum 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 Principle

Electrons fill the

lowest energy

orbitals first.

“Lazy Tenant

Rule”

Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem

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

4d 5s

5p

6s

7s

6p

6d

4f

5f

5d

En

erg

y

Energy Level Diagram of a Many-Electron Atom

Arbitrary

Energy 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 Principle

Each orbital can hold TWO electrons with opposite spins.


Wolfgang Pauli

RIGHT WRONG

General Rules

Hund’s Rule

Within a sublevel, place one electron per orbital

before pairing them.

“Empty Bus Seat Rule”


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

1s2 2s2 2p4

Notation

1s 2s 2p


O 15.9994

8

Orbital Filling

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

Orbital Filling


Electron Configurations

Electron

H

He

Li

C

N

O

F

Ne

Na

1s1

1s22s22p63s1

1s22s22p6

1s22s22p5

1s22s22p4

1s22s22p3

1s22s22p2

1s22s1

1s2

NOT CORRECT Violates Hund’s

Rule


Electron

H

He

Li

C

N

O

F

Ne

Na

1s1

1s22s22p63s1

1s22s22p6

1s22s22p5

1s22s22p4

1s22s22p3

1s22s22p2

1s22s1

1s2

Orbital Filling



Electron

H

He

Li

C

N

O

F

Ne

Na

1s1

1s22s22p63s1

1s22s22p6

1s22s22p5

1s22s22p4

1s22s22p3

1s22s22p2

1s22s1

1s2

Energy Level Diagram A

rbitra

ry E

ne

rgy S

cale

1s

2s 2p

3s 3p

4s 4p 3d

5s 5p 4d

6s 6p 5d 4f

NUCLEUS

Bohr Model

Electron Configuration

CLICK ON ELEMENT TO FILL IN CHARTS

N

H He Li C N Al Ar F Fe La


rbitra

ry E

ne

rgy S

cale

1s

2s 2p

3s 3p

4s 4p 3d

5s 5p 4d

6s 6p 5d 4f

NUCLEUS

Bohr Model



N

H = 1s1

Hydrogen



rbitra

ry E

ne

rgy S

cale

1s

2s 2p

3s 3p

4s 4p 3d

5s 5p 4d

6s 6p 5d 4f

NUCLEUS

Bohr Model



N

He = 1s2

Helium



rbitra

ry E

ne

rgy S

cale

1s

2s 2p

3s 3p

4s 4p 3d

5s 5p 4d

6s 6p 5d 4f

NUCLEUS

Bohr Model



N

Li = 1s22s1

Lithium



rbitra

ry E

ne

rgy S

cale

1s

2s 2p

3s 3p

4s 4p 3d

5s 5p 4d

6s 6p 5d 4f

NUCLEUS

Bohr Model



N

C = 1s22s22p2

Carbon



rbitra

ry E

ne

rgy S

cale

1s

2s 2p

3s 3p

4s 4p 3d

5s 5p 4d

6s 6p 5d 4f

NUCLEUS



N

N = 1s22s22p3

Bohr Model

Nitrogen

Hund’s Rule “maximum

number of unpaired

orbitals”.



rbitra

ry E

ne

rgy S

cale

1s

2s 2p

3s 3p

4s 4p 3d

5s 5p 4d

6s 6p 5d 4f

NUCLEUS

Bohr Model



N

F = 1s22s22p5

Fluorine



rbitra

ry E

ne

rgy S

cale

1s

2s 2p

3s 3p

4s 4p 3d

5s 5p 4d

6s 6p 5d 4f

NUCLEUS

Bohr Model



N

Al = 1s22s22p63s23p1

Aluminum



rbitra

ry E

ne

rgy S

cale

1s

2s 2p

3s 3p

4s 4p 3d

5s 5p 4d

6s 6p 5d 4f

NUCLEUS



N

Ar = 1s22s22p63s23p6

Bohr Model

Argon



rbitra

ry E

ne

rgy S

cale

1s

2s 2p

3s 3p

4s 4p 3d

5s 5p 4d

6s 6p 5d 4f

NUCLEUS


Fe = 1s22s22p63s23p64s23d6

N


Bohr Model

Iron



rbitra

ry E

ne

rgy S

cale

1s

2s 2p

3s 3p

4s 4p 3d

5s 5p 4d

6s 6p 5d 4f

NUCLEUS


La = 1s22s22p63s23p64s23d10

4s23d104p65s24d105p66s25d1

N


Bohr Model

Lanthanum


s p

d (n-1)

f (n-2) 6

7

Periodic Patterns

1s

2s

3s

4s

5s

6s

7s

3d

4d

5d

6d

1s

2p

3p

4p

5p

6p

7p

4f

5f

1

2

3

4

5

6

7

Periodic Patterns

Period #

energy level (subtract for d & f)

A/B Group #

total # of valence e-

Column within sublevel block

# of e- in sublevel


s-block 1st Period

1s1 1st column

of s-block

1

2

3

4

5

6

7

Periodic Patterns

Example - Hydrogen


Full energy level

1

2

3

4

5

6

7

• Full sublevel (s, p, d, f)

• Half-full sublevel

Stability


unit 5: light and electron...

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