1. Electron Structure of the Atom:
Configuration
Links for Chapter 7
Slide 3 07m01an1.mov fireworks
Slide 4 07m03an1.mov visible light as waves
Slide 4 waves_prop.exe wavelength and frequency
Slide 5 spectrum.exe range of radiation and applications
Slide 10 chm3d18s.mov continuous spectrum
Slide 11 chm3d19s.mov line spectrum
Slide 11 line_spectra.exe spectroscopy and 4 line spectra
Slide 16 bohr.exe animation of Bohr atom
Slide 17 absorb_emit_2.exe energy diagram
Slide 19 07m09an1.mov Bohr replaced by quantized atom
Slide 20 modern_atom_2.exe animation of modern atom
Slide 30 quantum_nos.exe physical significance of each
Slide 32 vd06_002.mov multielectron configurations and filling rules
Slide 41 filling_rules.exe check for violations
Slide 49 aufbau.exe stills of order and periodic table
Slide 61 ion_config.exe drag and drop drill
Slide 65 alk_met2.mov alkali metals + water
Slide 66 08m12an1.mov Mg 1st IE
Slide 66 08m12an2.mov Mg 2nd IE
Slide 67 ioniz_energy.exe trends in IE
Slide 70 alk_met2.mov alkali metals + water
Slide 71 08m12an1.mov Mg 1st IE
Slide 71 08m12an2.mov Mg 2nd IE
Slide 75 atomic_radii.exe trends in size
Slide 75 eff_nuclear_charge.exe trends in size with nuclear charge
Slide 77 ionic_radii.exe trends in ionic size with ion charge

2. MATTER elements Solid compounds Liquid mixtures Gas Chemical Change
Such as
Chemical Change
MATTER
Liquid
Gas
mixtures
compounds
elements
Physical property
Chemical Property
Solid
Physical Change
Can be classified into
Can undergo changes such as
Can be characterized by
Can be in different states such as
Density, MP, BP, polarity
Rxn with O2, CO2
Can combine chemically into
Can combine physically into
Can be described by KMT
Can be converted through melting into
Can be converted through evaporation into
Filtration, diffusion
Formation of H2O, H2, O2

3. Atomic Structural Theories: Thomson
Thomson – plum pudding model

4. Atomic Structural Theories: Rutherford
Rutherford – nuclear model

5. Atomic Structural Theories: Atomic Atomic Structural Theories: Bohr el
Bohr - planetary model

6. Atomic Structural Theories: Quantum Model

7. How is the electron configuration of an atom written?
The Big Question
How is the electron configuration of an atom written?

8. Introductory Experiment
Animation: fireworks

9. Orbital Diagrams Orbital diagrams
Show the sublevels and orbitals that can exist at each principal energy level.
Each box represents an orbital.
Groups of boxes represent sublevels.
Figure 7.17

10. Orbital Diagram: Hydrogen Atom
In the hydrogen atom only, the sublevels within a principal energy level all have the same energy.
Each box represents an orbital.

11. Orbital Diagram: Multielectron Atom
In multielectron atoms, the sublevels within a principal energy level have different energies.
Sublevels within a principal energy level split so that
s < p < d < f
Figure 7.18

12. Orbital Diagram Rules
Two principles and one rule determine how the electrons are filled in the principal energy levels and sublevels.
Electrons are always filled in their ground state, or lowest energy state.

13. Orbital Diagram Rules Aufbau principle:
Electrons fill orbitals starting with the lowest-energy orbitals.
Pauli exclusion principle:
A maximum of two electrons can occupy each orbital, and they must have opposite spins.
Hund’s rule:
Electrons are distributed into orbitals of identical energy (same sublevel) in such a way as to give the maximum number of unpaired electrons.

14. Orbital Diagrams
Electrons are represented by up and down arrows.

15. Orbital Diagrams
Electrons occupy the lowest-energy orbitals first (aufbau principle).
No more than two electrons occupy each orbital (Pauli exclusion principle).
Two electrons in the same orbital must have opposite spins, represented by the up and down arrows.

16. Orbital Diagram: Helium

17. Orbital Diagram: Lithium

18. Orbital Diagram: Boron

19. Orbital Diagram: Carbon
Why do the electrons in the p sublevel occupy separate orbitals?
It takes a little bit of energy to pair up electrons, so single electrons occupy different orbitals of the same energy (Hund’s Rule)

20. Orbital Diagram: Carbon

21. Electron Configurations
Shorthand notation which shows the distribution of electrons among sublevels

22. Electron Configurations
Electron configurations: Allow us to represent the arrangement of the electrons in an atom.

23. Electron Configuration

24. Electron Configurations
For elements in periods 1 and 2:
Figure 7.19

25. Problem
Use an orbital diagram to write the electron configuration for silicon:
Figure 7.18

26. Pneumonic device for electron configurations
The periodic table provides a simpler device for figuring out electron configurations.

27. Periodicity of Electron Configurations
Consider the alkali metals:
Li 1s22s1
Na 1s22s22p63s1
K 1s22s22p63s23p64s1
Rb 1s22s22p63s23p64s23d104p65s1
Can you see a pattern? Consider some more examples and look for patterns.

28. Periodicity of Electron Configurations
Consider the alkaline earth metals:
Be 1s22s2
Mg 1s22s22p63s2
Ca 1s22s22p63s23p64s2
Sr 1s22s22p63s23p64s23d104p65s2

29. Periodicity of Electron Configurations
Consider a few of the halogens:
F 1s22s22p5
Cl 1s22s22p63s23p5
Br 1s22s22p63s23p64s23d104p5

30. Periodicity of Electron Configurations
Consider some of the noble gases:
Ne 1s22s22p6
Ar 1s22s22p63s23p6
Kr 1s22s22p63s23p64s23d104p6

31. Conclusion
Electron configuration
and
periodic table placement?

32. Periodicity of Electron Configurations
Notice that the number of columns in the s, p, d, and f blocks is the same as the number of electrons allowed in each sublevel.
This allows us to use the periodic table to write electron configurations without the aid of an orbital diagram.

33. Periodicity of Electron Configurations
The periodic table can be used to fill orbital diagrams or to find electron configurations.
Figure 7.20

34. Periodicity of Electron Configurations
The principal energy level number, the number that comes before the sublevel letter designation, is the same as the period number for the s and p sublevels.
For the d sublevels, the principal energy level number is one less than the period number. Why?

36. The relation between orbital filling and the periodic table
Periodicity of Electron Configurations
The relation between orbital filling and the periodic table

37. Periodicity of Electron Configurations
Figure 7.21

38. Problem: electron configuration for phosphorus

39. Problem: electron configuration for phosphorus
Orbital Diagram: Carbon
1s2 2s2 2p6 3s2 3p3

40. Write the electron configuration for manganese:
Figure 7.22

41. Problem: electron configuration for manganese
1s2 2s2 2p6 3s2 3p6 4s2 3d5
Orbital Diagram: Carbon

42. Worksheet #2-1 Electron Configuration I:
Draw the electron configuration (long form) of the following elements just by looking at the periodic table.
Na S Eu
Ba F
Ga Ar
Sn Pb
Mo U

43. Condensed Electron Configurations
Abbreviated electron configurations are often used for elements with many electrons.
Notice that iron’s electron configuration starts out with argon’s electron configuration, but ends differently:
Fe 1s22s22p63s23p64s23d6
Ar 1s22s22p63s23p6
We use the symbol [Ar] to represent argon’s electron configuration:
Fe [Ar] 4s23d6

44. Periodicity of Electron Configurations

45. Periodicity of Electron Configurations

46. Figure 7.23

47. Worksheet #2- 2 Electron Configuration II:
Draw the electron configuration (condensed form) of the following elements just by looking at the periodic table.
Na S Eu
Ba F
Ga Ar
Sn Pb
Mo U

48. Valence Electrons for the Main-Group Elements
The last filled principal energy level is called the valence level, or valence shell.
The valence level contains electrons that are highest in energy and occupy orbitals that extend further from the nucleus than those in the lower levels.
Valence electrons occupy orbitals in the valence level. All the other electrons are called core electrons, or inner electrons.

49. Sample Problem: Valence Electrons
How many valence electrons in bromine?
Br 1s22s22p63s23p64s23d104p5
Bromine has 7 valence electrons (4s and 4p).

50. Sample Problem : Valence Electrons
How many valence electrons in Calcium?
Ca 1s22s22p63s23p64s2
Calcium has 2 valence electrons (4s).

51. Sample Problem: Valence Electrons
Determine the number of valence electrons in each of the following: F Li Na C Si Pb 7 1 4

52. Conclusion
Electronic configuration?
Valence electron?
Family Number?

53. Conclusion
The valence electrons of family A elements are the same as the family number. They can be seen in the outer most energy levels in the electron configuration of the element.
The same is not true for family B elements.

54. Electron Configurations for Ions
In atoms, the number of electrons is equal to the number of protons, which is the atomic number.
In ions, the number of electrons does not equal the atomic number. We must add or subtract electrons, depending on whether the ion is an anion or cation.

55. Electron Configurations for Ions
Write the electron configuration for Na+:
Na = 1s22s22p63s1
Na+ has a positive charge of 1; therefore, we need to subtract 1 electron from the total number of electrons, 11.
Na+ has 10 electrons and is iso-electronic with Ne.
1s22s22p6

56. Electron Configurations for Ions
Write the electron configuration for Cl-:
Cl = 1s22s22p63s23p5
Cl- has a negative charge of 1; therefore, we need to add 1 electron from the total number of electrons, 17.
Cl- has 18 electrons and is iso-electronic with Ar.
1s22s22p63s23p6

57. Worksheet #2-3 Electron Configuration of Ions: Ion
Write the electron configuration in condensed notation of the following ions.
Ion
Electron configuration
(condensed form) of the neutral atom
Electron configuration of the ion (condensed form)
Isoelectronic with
Br-
N3- K+
Sr2+
S2-
P3-
Ni2+
Al3+
Fe2+
Fe3+

58. Conclusion
Electron configuration of ions?
Family number?
Isoelectronic with?

59. Conclusion
Family A atoms form ions so as to have the same electron configuration as a noble gas element.
The charges of the ions formed can be determined from the family number of the element.

60. Conclusion
For family B metals, the electrons lost in ion formation come from the highest energy level filled (not the d-electrons yet)

61. Quantum Numbers Each electron has its own set of four quantum numbers.
These quantum numbers describe the location and the shape of the electron’s orbital.

62. Quantum Numbers Quantum Numbers and Atomic Orbitals
An atomic orbital is specified by four quantum numbers.
n the principal quantum number - a positive integer
l the angular momentum quantum number - an integer from 0 to n-1
ml the magnetic moment quantum number - an integer from -l to +l
ms the magnetic spin quantum number = -1/2 and + 1/2

63. Summary of Quantum Numbers of Electrons in Atoms
Name
Symbol
Permitted Values
Property
principal n
positive integers(1,2,3,…)
orbital energy (size)
angular momentum l
integers from 0 to n-1
orbital shape ( l = 0, 1, 2, and 3 correspond to s, p, d, and f orbitals, respectively.)
magnetic ml
integers from -l to 0 to +l
orbital orientation
spin ms
+1/2 or -1/2
direction of e- spin

64. Quantum Numbers
Table The Hierarchy of Quantum Numbers for Atomic Orbitals
Name, Symbol
(Property)
Allowed Values
Quantum Numbers
Principal, n
(size, energy)
Positive integer
(1, 2, 3, ...) 1 2 3 1 2
Angular momentum, l
(shape)
0 to n-1 1 +1 +2 -1 -2 -1 +1 -1 +1
Magnetic, ml
(orientation)
-l,…,0,…,+l

65. Quantum Numbers Where can you find Donna?
Donna lives in a dorm in a condominium unit. In the dorm floor, there are male and female sections per floor. Per room, there are two beds only: one near the window, one not. If she is asked, where EXACTLY she lives/sleeps, how would she answer?
Prince David Condominium in Katipunan Ave
At the 3rd floor
Female section
Room 314
Bed near window

66. Quantum Numbers Where can you find the electron?
The quantum mechanical model uses a certain way to describe an orbital. You can say you are asking the question, Where does my electron live/reside?
We use three quantum numbers to describe an orbital. We add a fourth to pinpoint the electron in that orbital
Principal quantum no. (n)
Azimuthal or Angular Momentum quantum no. (l)
Magnetic quantum no. (ml)
Spin quantum no. (ms)

67. Quantum Numbers Prince David Condominium in Katipunan Ave
The electron belongs to Chlorine
At the 3rd floor
At the 3rd energy level (n=3)
Female section
In the p-subshell (l=1)
In one of the three degenerate orbitals
eg. ml= 0
Room 314
Bed near window
Electron is spin-up
eg. ms= +1/2

68. Sample Problem What are the quantum numbers of a 1s1 electron? Answer:
ml = 0
ms = -1/2

69. Sample Problem What are the quantum numbers of a 3p2 electron? Answer:
ml = 0
ms = -1/2

70. Sample Problem What are the quantum numbers of a 5d7 electron? Answer:
ml = -1
ms = + 1/2

71. Worksheet #2-4 n l ml ms Electron Quantum Numbers: electrons
Write the quantum numbers of the following electrons.
electrons n l ml ms
2s1
3p5
3d3
4d7
4f4

72. Summary of Electron Configuration Concepts
Long form
Condensed form
Ions, iso-electronic, family A and B elements
Family Number/Period Number
Valence electrons
Quantum numbers

73. Points to Ponder…..
Is there a proton configuration or a neutron configuration? Why or why not?
How do scientists synthesize new elements?
What are the newest four elements added to the periodic table?
Is there a limit to the number of elements that scientists can synthesize?