1. Electron Configurations
Chapter 5
Electron Configurations

2. Light - Light has properties of both waves and particles
Properties of Waves
Amplitude – height of a wave
Wavelength () – distance between waves or distance between two corresponding points
Frequency () – how fast the wave oscillates or number of waves per second
Speed – Speed of light (c) = 3.00 x 108 m/s
All waves (electromagnetic, water) are described using these four properties

3. Wavelength
Amplitude
Frequency : unit = cycles/sec = 1/s = s-1 = Hertz

4. Speed of Light (c)
- Light moves at a constant speed (c = 3.00 x 108 m/s)
- Creates a relationship between frequency and wavelength
wavelength () = speed of light (c) / frequency()
which can be written
 = c / 
Example Calculate the wavelength of visible light with a frequency of 5.5 x 1014 s-1.
Given:  = 5.5 x 1014 s-1
= 3.00 x 108 (m/s) / 5.5 x 1014 (1/s)
= 5.5 x 10-7 m
c = 3.00 x 108 m/s
Find: 
Equation:  = c/ 

5. Electromagnetic radiation is a form of energy that exhibits wavelike behavior
Electromagnetic spectrum (EM) encompasses all the forms of radiation
Atomic emission spectrum of an element is the set of frequencies of the electromagnetic waves emitted by an atom

6. Electromagnetic Spectrum
700 nm
400 nm
Figure 4-7, Page 129

7. Energy
E= hν
h= 6.626x10^34 Joules/second

9. Quantum Theory: Plank’s Theory
- There is a fundamental restriction on the amount of energy that an object emits or absorbs
- Energy is emitted or absorbed in “Pieces” of particular size called quantum: is the minimum amount of energy that can be gain or lost by an atom
- Quantum theory contradicts classical theory which states, an object can absorb or emit any amount of energy, so the energy it can posses forms a continuum of values
Quantum Theory answers the question:
Why electromagnetic radiation is emitted by hot objects

10. Essence of Plank’s Theory
- provides a relationship between frequency () and energy (E)
E = h 
where h = plank’s constant = 6.626x10-34 J.s
 = frequency = Hertz (s-1)
E = energy = Joule (J)
- showing that, energy is quantized; restricted to certain quantities
Example What if your car was quantized?

11. - Einstein used this idea of quantized energy to explain a
- Einstein used this idea of quantized energy to explain a phenomenon called the photoelectric effect
Photoelectric Effect
e- are ejected from the surface of a metal when light shines on the metal
Einstein concluded that light is quantas of energy called photons
Photons (quantas of light energy) strike the surface of the metal
Step 1
The energy is transferred to the e- in a metal atom
Step 2

12. Step 3
The e- “swallows” the entire photon, OR
The e- “swallows” none of the photon
* Energy is consumed all or nothing*
Step 4
(a) If there is NOT enough energy in a particular photon: e- stays put
No “roll over” plan. Energy does NOT collect. No mater how many times you hit with the same energy photon
(b) If there is enough energy in a particular photon: e- is ejected from surface
Conclusion
The frequency, and therefore energy, is important in a photon, not the intensity of the light
Figure 4-12, Page 133

13. Vocabulary Line Spectrum –
A spectrum that contains only certain colors, or wavelengths
Ex. Street lights, neon lights
Continuous – Spectrum
A spectrum that contains all colors, or wavelengths, which fade into eachother
Ex. Electromagnetic spectrum, sunlight, filament bulb
Quantum number (n) -
Indicates an energy level
Ground State (n=1) -
Lowest energy level; orbital closest to the nucleus
Excited State (n=2, ...) -
energy levels above ground state achieved by electrons thru absorbing energy
Atomic orbital –
the region around the nucleus where an electron with a given energy is likely to be found
Heisenberg’s Uncertainty -Principal
The position and momentum of an e- cannot be simultaneously be known

15. ENERGY
E = hυ
h=6.636x10^-34
Max Planck

18. Bohr’s Model of the atom
Quantum # (n)-
Indicated energy level or orbital
Neils Bohr
n = 1 +
n = 2
The probability of finding e- in certain regions of an atom is described by an orbital
n = 3
n = 4
Orbitals have characteristic shapes, size and energies, but do NOT tell how e- move
The larger the orbital, the further the e- are from the nucleus

19. - There are four types of orbitals: s, d, p, f

20. s p d f Electron Configurations 1 2 1 2 3 4 5 6 7 1 2 3 4 5 6
1 2
valence e- = outermost e- 1 2 3 4 5 6 7 s
Columns (top to bottom) = group/family
Rows (left to right) = period 2 p 3 3 d 4 4 5 5 6 6 7 4 f
energy levels 5

21. Quantum model

22. Electron Spin
- e- spin either clockwise or counterclockwise which creates a magnetic field
each orbital in an atom can hold up to 2e- that must have opposite spin ( and )
Pauli Exclusion Principle –
- an orbital with 2e- of opposite spin are said to have a pair of e-
Sublevels # Orbitals Max # of e- s p d f
Figure 4-24

23. Electron Configurations
Definition
Distribution of e- among orbitals; describes where e- are and what energy they have
Aufbau Principle –
e- are added one at a time to the lowest energy level available
Hund Rule –
e- occupy equal energy orbitals so the maximum number of unpaired e- result
3s _____
2p _____ _____ _____
2s _____
1s _____         
Figure 4-24

24. Electron Configurations
Definition
Distribution of e- among orbitals; describes where e- are and what energy they have
Aufbau Principle –
e- are added one at a time to the lowest energy level available
Hund Rule –
e- occupy equal energy orbitals so the maximum number of unpaired e- result
3s _____
2p _____ _____ _____
2s _____
1s _____         
Figure 4-24

25. Electron Configurations
Definition
Distribution of e- among orbitals; describes where e- are and what energy they have
Aufbau Principle –
e- are added one at a time to the lowest energy level available
Hund Rule –
e- occupy equal energy orbitals so the maximum number of unpaired e- result
_____ _____ _____ _____ _____
1s s px 2py pz
1s2 2s2 2p6         

26. 1s2 2s2 2p6
Orbital Last level of energy
Number of electrons in a particular orbital
Level of energy
This particular atoms has
2 levels of energy
10 electron total
8 electrons in the last level of energy 2 +6

27. How To Do Energy Diagrams
Step 1
Determine atomic number
Step 2
Determine number of e-
- if neutral: # e- = atomic #
- if ion: # e- = atomic # - charge
Step 3
Fill in atomic orbital energy diagram using following principles
- Pauli: 2e- max per orbital with opposite spin
- Aufba: 1e- at a time filling lowest energy levels first
- Hund: max # of unpaired e-
Step 4
Determine number of paired and unpaired e-
Step 5
Write e- configuration

28. Example. Determine the e- configuration of Ne by using an
Example Determine the e- configuration of Ne by using an atomic orbital energy diagram
3s _____
2p _____ _____ _____
2s _____
1s _____
Atomic # = 10
# e- = 10 – 0 = 10
Paired = 5
Unpaired = 0        
e- config: 1s22s22p6  
Example Determine the e- configuration of S by using an atomic orbital energy diagram
4s _____
3p _____ _____ _____
3s _____
2p _____ _____ _____
2s _____
1s _____
Atomic # = 16
# e- = 16 – 0 = 16
Paired = 7
Unpaired = 2      
e- config: 1s22s22p63s23p4          

29. Example. Determine the e- configuration of Fe+ by using an
Example Determine the e- configuration of Fe+ by using an atomic orbital energy diagram
3d _____ _____ _____ _____ _____
4s _____
3p _____ _____ _____
3s _____
2p _____ _____ _____
2s _____
1s _____       
Atomic # = 26
# e- = 26 – 1 = 25
Paired = 10
Unpaired = 5                
e- config: 1s22s22p63s23p64s23d5  
Example Determine the e- configuration of F- by using an atomic orbital energy diagram
3s _____
2p _____ _____ _____
2s _____
1s _____
Atomic # = 9
# e- = 9 – -1 = 10
Paired = 5
Unpaired = 0        
e- config: 1s22s22p6  

30. Order of Energy Levels from Lowest (1s) to Highest
Group 1 – Alkali Metals
Group 2 – Alkaline Earth Metals
Group – Transition Metals
Group 3 – Boron Group
Group 4 – Carbon Group
Group 5 – Nitrogen Group
Group 6 – Oxygen Group
Group 7 – Halogens
Group 8 – Nobel Gas
Period 4f– Lanthanides
Period 5f– Actinides
Start with 1s and read up the arrow