1. Atomic Electron Configurations and Chemical Periodicity
Chapter 8
Atomic Electron Configurations
and Chemical Periodicity
Dr. S. M. Condren

2. ATOMIC ELECTRON CONFIGURATIONS AND PERIODICITY
Dr. S. M. Condren

3. Atomic Orbitals
Types of orbitals found in the known elements: s, p, d, and f
schools play defensive football
Packer version: secondary pass defense fails
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4. Atomic Orbitals Shapes s – spherical p – dumbbell d – complex
f – very complex
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5. Arrangement of Electrons in Atoms
Electrons in atoms are arranged as
SHELLS (n)
SUBSHELLS (l)
ORBITALS (ml)
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6. Arrangement of Electrons in Atoms
Each orbital can be assigned no more than 2 electrons!
This is tied to the existence of a 4th quantum number, the electron spin quantum number, ms.
Dr. S. M. Condren

7. Electron Spin Quantum Number, ms
Can be proved experimentally that electron
has a spin. Two spin directions are given by
ms where ms = +1/2 and -1/2.
Dr. S. M. Condren

8. Electron Spin and Magnetism
Diamagnetic: NOT attracted to a magnetic field
Paramagnetic: substance is attracted to a magnetic field.
Substances with unpaired electrons are paramagnetic.
Dr. S. M. Condren

9. Measuring Paramagnetism
Paramagnetic: substance is attracted to a magnetic field. Substance has unpaired electrons.
Diamagnetic: NOT attracted to a magnetic field
Dr. S. M. Condren
Active Figure 8.2

10. QUANTUM NUMBERS Now there are four! n ---> shell 1, 2, 3, 4, ...
l ---> subshell 0, 1, 2, ... n - 1
ml ---> orbital -l l
ms ---> electron spin +1/2 and -1/2
Dr. S. M. Condren

11. Pauli Exclusion Principle
No two electrons in the same atom can have the same set of 4 quantum numbers.
That is, each electron has a unique address.
Dr. S. M. Condren

12. Electrons in Atoms When n = 1, then l = 0
this shell has a single orbital (1s) to which 2e- can be assigned
When n = 2, then l = 0, 1
2s orbital e-
three 2p orbitals 6e-
TOTAL = 8e-
Dr. S. M. Condren

13. Electrons in Atoms When n = 3, then l = 0, 1, 2 3s orbital 2e-
three 3p orbitals 6e-
five 3d orbitals 10e-
TOTAL = e-
Dr. S. M. Condren

14. Electrons in Atoms When n = 4, then l = 0, 1, 2, 3 4s orbital 2e-
three 4p orbitals 6e-
five 4d orbitals 10e-
seven 4f orbitals 14e-
TOTAL = 32e-
And many more!
Dr. S. M. Condren

15. Dr. S. M. Condren

16. Assigning Electrons to Atoms
Electrons generally assigned to orbitals of successively higher energy.
For H atoms, E = - C(1/n2). E depends only on n.
For many-electron atoms, energy depends on both n and l.
Dr. S. M. Condren

17. Electron Filling Order
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18. LED Traffic Lights
Chapter 7, Problem 3, page 326 text
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19. Writing Atomic Electron Configurations
Two ways of writing configs. One is called the spdf notation. 1 s
value of n
value of l
no. of
electrons
spdf notation
for H, atomic number = 1
Dr. S. M. Condren

20. Writing Atomic Electron Configurations
Other is called the orbital box notation
One electron has n = 1, l = 0, ml = 0, ms = + 1/2
Other electron has n = 1, l = 0, ml = 0, ms = - 1/2
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21. See “Toolbox” on CD for Electron Configuration tool.
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22. Electron Configurations and the Periodic Table
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23. Lithium Group 1A Atomic number = 3 1s22s1 ---> 3 total electrons
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24. Beryllium Group 2A Atomic number = 4 1s22s2 ---> 4 total electrons
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25. Boron Group 3A Atomic number = 5 1s2 2s2 2p1 ---> 5 total electrons
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26. Carbon Group 4A Atomic number = 6 1s2 2s2 2p2 --->
6 total electrons
Here we see for the first time HUND’S RULE. When placing electrons in a set of orbitals having the same energy, we place them singly as long as possible.
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27. Nitrogen Group 5A Atomic number = 7 1s2 2s2 2p3 --->
7 total electrons
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28. Oxygen Group 6A Atomic number = 8 1s2 2s2 2p4 --->
8 total electrons
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29. Fluorine Group 7A Atomic number = 9 1s2 2s2 2p5 --->
9 total electrons
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30. Neon Group 8A Atomic number = 10 1s2 2s2 2p6 --->
10 total electrons
Note that we have reached the end of the 2nd period, and the 2nd shell is full!
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31. Sodium Group 1A Atomic number = 11 1s2 2s2 2p6 3s1 or
“neon core” + 3s1
[Ne] 3s1 (uses rare gas notation)
Note that we have begun a new period.
All Group 1A elements have [core]ns1 configurations.
Dr. S. M. Condren

32. Aluminum Group 3A Atomic number = 13 1s2 2s2 2p6 3s2 3p1 [Ne] 3s2 3p1
All Group 3A elements have [core] ns2 np1 configurations where n is the period number.
Dr. S. M. Condren

33. Phosphorus Group 5A Atomic number = 15 1s2 2s2 2p6 3s2 3p3
Yellow P
Red P
Group 5A
Atomic number = 15
1s2 2s2 2p6 3s2 3p3
[Ne] 3s2 3p3
All Group 5A elements have [core ] ns2 np3 configurations where n is the period number.
Dr. S. M. Condren

34. Calcium Group 2A Atomic number = 20 1s2 2s2 2p6 3s2 3p6 4s2 [Ar] 4s2
All Group 2A elements have [core]ns2 configurations where n is the period number.
Dr. S. M. Condren

35. Transition Metals Table 8.4
All 4th period elements have the configuration [argon] nsx (n - 1)dy and so are d-block elements.
Chromium
Iron
Copper
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36. Transition Element Configurations
3d orbitals used for Sc-Zn (Table 8.4)
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37. Dr. S. M. Condren

38. Board Work V – electron configuration Cr – electron configuration
Mn – electron configuration
Ni – electron configuration
Cu – electron configuration
Zn – electron configuration
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39. Magnetism Paramagnetism Ferromagnetism
Spins are randomized by thermal energy.
Spins are aligned with or against
an applied magnetic field.
Ferromagnetism
Spins are aligned with an
applied magnetic field.
Spins are ordered in magnetic domains.
Dr. S. M. Condren

40. NMR and MRI http://mrsec.wisc.edu/Edetc/background/NMR/index.html
Nuclei also have spin and nuclear quantum numbers
800 MHz, 18.8 T NMR spectrometer
Open Magnet Design MRI
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41. Memory Metal
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42. Nitinol, NiTi
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43. Lanthanides and Actinides
All these elements have the configuration [core] nsx (n - 1)dy (n - 2)fz and so are f-block elements.
Cerium
[Xe] 6s2 5d1 4f1
Uranium
[Rn] 7s2 6d1 5f3
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44. Lanthanide Element Configurations
4f orbitals used for Ce - Lu and 5f for Th - Lr (Table 8.2)
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45. Dr. S. M. Condren

46. Ion Configurations
To form cations from elements remove 1 or more e- from subshell of highest n [or highest (n + l)].
P [Ne] 3s2 3p e > P3+ [Ne] 3s2 3p0
Dr. S. M. Condren

47. Ion Configurations
For transition metals, remove ns electrons and then (n - 1) electrons.
Fe [Ar] 4s2 3d6
loses 2 electrons ---> Fe2+ [Ar] 4s0 3d6
To form cations, always remove electrons of highest n value first!
Dr. S. M. Condren

48. Quantum Numbers
What is one of the sets of quantum numbers for the 4s electrons in calcium?
n = 4; l = 0; ml = 0; s = +1/2 or
n = 4; l = 0; ml = 0; s = -1/2
Dr. S. M. Condren

49. Quantum Numbers
What is one of the sets of quantum numbers for the 3p electrons in sulfur?
n = 3; l = 1; ml = +1; s = +1/2 or
n = 3; l = 1; ml = +1; s = -1/2 or
n = 3; l = 1; ml = 0; s = +1/2 or
n = 3; l = 1; ml = 0; s = -1/2 or
n = 3; l = 1; ml = -1; s = +1/2 or
n = 3; l = 1; ml = -1; s = -1/2
Dr. S. M. Condren

50. Quantum Numbers
What is one of the sets of quantum numbers for the 3d electrons in Fe?
n = 3; l = 2; ml = +2; s = +1/2
or n = 3; l = 2; ml = +2; s = -1/2
or n = 3; l = 2; ml = +1; s = +1/2
or n = 3; l = 2; ml = +1; s = -1/2
or n = 3; l = 2; ml = 0; s = +1/2
or n = 3; l = 2; ml = 0; s = -1/2
or n = 3; l = 2; ml = -1; s = +1/2
or n = 3; l = 2; ml = -1; s = -1/2
or n = 3; l = 2; ml = -2; s = +1/2
or n = 3; l = 2; ml = -2; s = -1/2
Dr. S. M. Condren

51. Announcements You may bring a 4x6 index card with information
A periodic table and a table of thermodynamic data will be furnished.
You need to know your TAs name and your section number.
Photo ID will be required when submitting your exam.
Dr. S. M. Condren

52. Announcements General Chemistry 103 Hour Exam 2 Nov. 6, 2006
Teaching Assistant _________________________ Section _____ Name _________________________________ c
General Chemistry 103
Hour Exam 2
Nov. 6, 2006
ALL WORK MUST APPEAR ON TEST FOR ANY CREDIT.
Work includes “stating the question in a mathematical form.”
A box should be drawn around the answer to be graded for a problem.
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53. Announcements Last day to drop
Suzie and Christie have papers to return, please see them after class
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54. Bonus Points Exam II – worth 105 points, count as 100
5 pts - Available through “Other Lecture Documents” this week, due Friday Nov. 10
Exam III – worth 105 points, count as 100
5 pts - Available through “Other Lecture Documents” later, due Friday Dec. 15
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55. Ion Configurations How do we know the configurations of ions?
Determine the magnetic properties of ions.
Sample of Fe2O3
Sample of Fe2O3 with strong magnet
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56. General Periodic Trends
Atomic and ionic size
Ionization energy
Electron affinity
Higher effective nuclear charge
Electrons held more tightly
Larger orbitals.
Electrons held less
tightly.
Dr. S. M. Condren

57. Effective Nuclear Charge, Z*
Atom Z* Experienced by Electrons in Valence Orbitals Li Be B C N O F
Increase in Z* across a period
[Values calculated using Slater’s Rules]
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58. Orbital Energies Orbital energies “drop” as Z* increases
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59. Atomic Radii
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60. Atomic Size Size goes UP on going down a group.
Because electrons are added further from the nucleus, there is less attraction.
Size goes DOWN on going across a period.
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61. Atomic Radius Increase in Z*
Size decreases across a period owing to increase in Z*. Each added electron feels a greater and greater + charge.
Large
Small
Increase in Z*
Dr. S. M. Condren

62. Trends in Atomic Size
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63. Sizes of Transition Elements
3d subshell is inside the 4s subshell.
4s electrons feel a more or less constant Z*.
Sizes stay about the same and chemistries are similar!
Dr. S. M. Condren

64. Density of Transition Metals
6th period
5th period
4th period
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65. Ion Sizes Does the size go
up or down when losing an electron to form a cation?
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66. Ion Sizes CATIONS are SMALLER than the atoms from which they come.Li +
, 78 pm
2e and 3 p
Forming a cation.
Li,152 pm
3e and 3p
CATIONS are SMALLER than the atoms from which they come.
The electron/proton attraction has gone UP and so size DECREASES.
Dr. S. M. Condren

67. Ion Sizes
Does the size go up or down when gaining an electron to form an anion?
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68. Ion Sizes ANIONS are LARGER than the atoms from which they come.
Forming an anion. F -
, 133 pm
10 e and 9 p
F, 71 pm
9e and 9p
ANIONS are LARGER than the atoms from which they come.
The electron/proton attraction has gone DOWN and so size INCREASES.
Trends in ion sizes are the same as atom sizes.
Dr. S. M. Condren

69. Trends in Ion Sizes
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70. Trends in Ionization Energy
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71. 2nd IE / 1st IE Li Na K B Al
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72. Electron Affinity A few elements GAIN electrons to form anions.
Electron affinity is the energy involved when an atom gains an electron to form an anion.
A(g) + e- ---> A-(g)
E.A. = ∆E
Dr. S. M. Condren

73. Electron Affinity of Oxygen
∆E is EXOthermic because O has an affinity for an e-.
[He]  
O atom
+ electron O
[He]   -
ion
EA = kJ
Dr. S. M. Condren

74. Electron Affinity of Nitrogen
[He]   N
atom
∆E is zero for N- due to electron-electron repulsions.
+ electron
[He]  
N- ion
EA = 0 kJ
Dr. S. M. Condren

75. Announcements You may bring a 4x6 index card with information
A periodic table and a table of thermodynamic data will be furnished.
You need to know your TAs name and your section number.
Photo ID will be required when submitting your exam.
Dr. S. M. Condren

76. Announcements Last day to drop
Suzie and Christie have papers to return, please see them after class
Dr. S. M. Condren