1. Modern Chemistry Chapter 4 Arrangement of Electrons in Atoms
Sections 1-3
The Development of a New Atomic Model
The Quantum Model of the Atom
Electron Configurations

2. The Quantum Model of the Atom
Section 2
The Quantum Model of the Atom
Chapter 4 Section 2 The Quantum Model pages

3. Chapter 4 Section 2 The Quantum Model pages 104-110
Electrons As Waves
Electrons can have wave and particle characteristics (like light).
Waves (electrons) confined to a space can have only certain frequencies
The frequencies correspond to Bohr’s orbits.
Louis de Broglie
Chapter 4 Section 2 The Quantum Model pages

4. Chapter 4 Section 2 The Quantum Model pages 104-110
Electrons As Waves
This is confirmed by experiments
Electrons, like waves, can be bent, diffracted and have interference
Diffraction: the bending of a wave as it passes through a small opening
Interference: when waves overlap.
Chapter 4 Section 2 The Quantum Model pages

5. The Heisenberg Uncertainty Principle
Involves the detection of electrons
To detect an electron a photon is used
The photon interacts with the electron and changes its course
There is uncertainty in trying to locate an electron.
Chapter 4 Section 2 The Quantum Model pages

6. The Heisenberg Uncertainty Principle
It is impossible to determine simultaneously both the position and velocity of an electron or any other particle.
Chapter 4 Section 2 The Quantum Model pages

7. The Schrödinger Wave Equation
Developed an equation that treats electrons as waves
Proved the quantization of electron energies
Quantum theory: describes mathematically the wave properties of electrons and other small particles
Chapter 4 Section 2 The Quantum Model pages

8. The Schrödinger Wave Equation
Solutions to the equations are wave functions.
Wave functions give the probability of finding electrons.
Electrons do not travel in neat orbits.
Electrons exist in regions called orbitals.
Orbital: a three dimensional region around the nucleus that indicates the probable location of electrons.
Chapter 4 Section 2 The Quantum Model pages

9. Heisenbery Uncertainty Principle Animation
Chapter 4 Section 2 The Quantum Model pages

10. Atomic Orbitals and Quantum Numbers
Quantum numbers specify the properties of atomic orbitals and the properties of electrons in the orbital.
The first three numbers result from the solution to Schrodinger’s wave equation.
Chapter 4 Section 2 The Quantum Model pages

11. Principle Quantum Number1
Symbol = n
Energy Level
n = 1, 2, 3, 4, 5, 6, 7 (whole numbers)
As n increases the electron’s energy and average distance from the nucleus increases.
Chapter 4 Section 2 The Quantum Model pages

12. Angular Momentum Quantum Number2
Symbol = l
Shape of orbital (sublevel)
l = s, p, d, f
A sublevel is made up of a certain number of orbitals
Chapter 4 Section 2 The Quantum Model pages

13. Atomic Orbitals and Quantum Numbers
Sublevel
Orbitals
Electrons s 1 2 p 3 6 d 5 10 f 7 14
Chapter 4 Section 2 The Quantum Model pages

14. Magnetic Quantum Number3
Symbol = m
Orientation around the nucleus
m = x, y, z, xy, yz, xz
Chapter 4 Section 2 The Quantum Model pages

15. Chapter 4 Section 2 The Quantum Model pages 104-110
Spin Quantum Number 4
Symbol = ms
Spin State of the electron
m = +1/2, -1/2
When electrons spin they produce a magnetic field.
Two electrons can exist in one orbital.
Each electron must have an opposite spin state.
Chapter 4 Section 2 The Quantum Model pages

16. # of electrons on a energy level
7s2 7p6 7d f14 7g 7h 7i
6s2 6p6 6d f14 6g 6h
5s2 5p6 5d f14 5g
4s2 4p d f14
3s2 3p6 3d10
2s2 2p6
1s2
# of electrons on a energy level
32e- =
18e- =
8e- = 2 + 6
2e- = 2 in the s orbital
Chapter 4 Section 2 The Quantum Model pages

17. Electron Configurations
Section 3
Electron Configurations
Chapter 4 Section 3 Electron Configurations pages

18. Chapter 4 Section 3 Electron Configurations pages 110-122
Aufbau principle
Pauli exclusion principle
Hund’s Rule
Noble Gas
Noble Gas configurations
Section 3 Vocabulary
Chapter 4 Section 3 Electron Configurations pages

19. Rules Governing Electron Configurations
Aufbau Principle
An electron occupies the lowest energy orbital that can receive it
Less energy is required for electrons to pair up in the 4s than the 3d.
Aufbau: German for construction
Chapter 4 Section 3 Electron Configurations pages

20. Aufbau Principle Animation
Chapter 4 Section 3 Electron Configurations pages

21. Sublevel Filling Order
7s 7p 7d 7f 7g 7h 7i
6s 6p 6d 6f 6g 6h
5s 5p 5d 5f 5g
4s 4p 4d 4f
3s 3p 3d
2s 2p 1s
Sublevel Filling Order
Chapter 4 Section 3 Electron Configurations pages

22. Rules Governing Electron Configurations
Pauli Exclusion Principle
No two electrons in the same atom can have the same set of four quantum numbers.
Electrons must have opposite spin states
Two electrons can exist in an orbital.
Chapter 4 Section 3 Electron Configurations pages

23. Chapter 4 Section 3 Electron Configurations pages 110-122
Pauli and Bohr
Chapter 4 Section 3 Electron Configurations pages

24. Pauli Exclusion Principle Animation
Chapter 4 Section 3 Electron Configurations pages

25. Rules Governing Electron Configurations
Hund’s Rule
Orbitals of equal energy are each occupied by one electron before any orbital is occupied by a second electron, and all electrons in singly occupied orbitals must have the same spin state.
Repulsion between electrons is minimized.
Chapter 4 Section 3 Electron Configurations pages

26. Chapter 4 Section 3 Electron Configurations pages 110-122

27. Chapter 4 Section 3 Electron Configurations pages 110-1223d 4d 5s 5p 6s 5d 6p 6d 7s 4f 5f
Chapter 4 Section 3 Electron Configurations pages

28. Chapter 4 Section 3 Electron Configurations pages 110-122
PRACTICE
Page 113 # 1 & 2
Write the electron configurations for the following elements: Ne, Na, Mg, Ar, K
p. 113
Chapter 4 Section 3 Electron Configurations pages

29. Orbital Notation Animation
Chapter 4 Section 3 Electron Configurations pages

30. Representing Electron Configurations
Orbital Notation
     . 1s 2s 2p
Which element is this?
How does this show Hund’s rule?
Chapter 4 Section 3 Electron Configurations pages

31. Chapter 4 Section 3 Electron Configurations pages 110-122
Orbital Diagram for Si
orbital
14 electrons
electron
(-1/2 spin) 1s 2s 2p 3s 3p
electron
(+1/2 spin)
sublevel
Chapter 4 Section 3 Electron Configurations pages

32. Shapes of s, p and d orbitals Image
Chapter 4 Section 3 Electron Configurations pages

33. Representing Electron Configurations
Orbital Notation
     . 1s 2s 2p
Electron Configurations
1s2 2s2 2p3
Use superscripts instead of lines and arrows.
Chapter 4 Section 3 Electron Configurations pages

34. Reading Electron Configuration Notation Animation
Chapter 4 Section 3 Electron Configurations pages

35. Electron Configurations
For Manganese – 25 electrons
1s 2s 2p 3s 3p 4s 3d 2 2 6 2 6 2 5
number of electrons in the sublevel
sublevel
Chapter 4 Section 3 Electron Configurations pages

36. Electron Configuration Animation
p. xx
Chapter 4 Section 3 Electron Configurations pages

37. Chapter 4 Section 3 Electron Configurations pages 110-122
PRACTICE
Page 113 # 1 & 2
Write the electron configurations for the following elements: Ne, Na, Mg, Ar, K
p. 113
Chapter 4 Section 3 Electron Configurations pages

38. Elements of the Second Period
3Li = 1s2 2s1
6C = 1s2 2s2 2p2
Inner shell electrons
Highest occupied energy level
C = 4 valence electrons Li = 1 valence electron
Valence electrons: electrons occupying the highest energy level in an atom
Chapter 4 Section 3 Electron Configurations pages

39. Elements of the Third Period
10Ne =
11Na =
12Mg =
18Ar =
19K =
1s2 2s2 2p6
1s2 2s2 2p6 3s1
1s2 2s2 2p6 3s2
1s2 2s2 2p6 3s2 3p6
1s2 2s2 2p6 3s2 3p6 4s1
Chapter 4 Section 3 Electron Configurations pages

40. Elements of the Third Period
Look! It’s neon!
10Ne =
11Na =
12Mg =
18Ar =
19K =
1s2 2s2 2p6
1s2 2s2 2p6 3s1
1s2 2s2 2p6 3s2
1s2 2s2 2p6 3s2 3p6
1s2 2s2 2p6 3s2 3p6 4s1
Ar?!
Chapter 4 Section 3 Electron Configurations pages

41. Elements of the Third Period
10Ne =
11Na =
12Mg =
18Ar =
19K =
1s2 2s2 2p6
1s2 2s2 2p6 3s1
1s2 2s2 2p6 3s2
1s2 2s2 2p6 3s2 3p6
1s2 2s2 2p6 3s2 3p6 4s1
[Ne]
[Ne]
[Ar]
Chapter 4 Section 3 Electron Configurations pages

42. Elements of the Third Period
10Ne =
11Na =
12Mg =
18Ar =
19K =
1s2 2s2 2p6
[Ne] 3s1
[Ne] 3s2
1s2 2s2 2p6 3s2 3p6
[Ar] 4s1
Chapter 4 Section 3 Electron Configurations pages

43. Noble Gas Notation Animation
Chapter 4 Section 3 Electron Configurations pages

44. Noble Gas Configuration
Find the noble gas with an atomic number closest to but less than the element’s atomic number.
Find the next sublevel after that noble gas
Fill in sublevels with the “leftover” electrons. (atomic # of element – atomic # of noble gas)
Chapter 4 Section 3 Electron Configurations pages

45. Noble Gas Configurations
2p6
3p6
4p6
5p6
6p6
Chapter 4 Section 3 Electron Configurations pages

46. Chapter 4 Section 3 Electron Configurations pages 110-122

47. Chapter 4 Section 3 Electron Configurations pages 110-1223d 4d 5s 5p 6s 5d 6p 6d 7s 4f 5f
Chapter 4 Section 3 Electron Configurations pages

48. Elements of the Fourth Period
Deviations
24Cr =
24Cr = [Ar] 3d5 4s1
unpaired electrons give a more stable arrangement with a lower energy
29Cu =
29Cu = [Ar] 3d10 4s1
No explanation for either
[Ar] 4s2 3d4
WRONG!!!
[Ar] 3d9 4s2
WRONG!!!
Chapter 4 Section 3 Electron Configurations pages

49. Elements of the Fourth Period
Even though the d sublevel fills before the p sublevel, the s sublevel is moved to be with the p sublevel.
53I = [Kr] 5s2 4d10 5p5 is written as…
53I = [Kr] 4d10 5s2 5p5
The sublevels on the same energy level are together.
It also shows the valence electrons.
Chapter 4 Section 3 Electron Configurations pages

50. Elements of the Fifth Period
Y [Kr] 4d1 5s2 Zr [Kr] 4d2 5s2
Nb [Kr] 4d3 5s2
Mo [Kr] 4d4 5s2
Tc [Kr] 4d5 5s2
Ru [Kr] 4d6 5s2 Rh [Kr] 4d7 5s2
Pd [Kr] 4d8 5s2
Ag [Kr] 4d9 5s2
Cd [Kr] 4d10 5s2
expected
deviations
Nb [Kr] 4d4 5s1
Mo [Kr] 4d5 5s1
Tc [Kr] 4d6 5s1
Ru [Kr] 4d7 5s1 Rh [Kr] 4d8 5s1
Pd [Kr] 4d10
Ag [Kr] 4d10 5s1
p.120
Chapter 4 Section 3 Electron Configurations pages

51. Chapter 4 Section 3 Electron Configurations pages 110-122
PRACTICE
Page 121 #1-4
p. 113
Chapter 4 Section 3 Electron Configurations pages

52. Elements of the Sixth Period
4f and 5d are very close in energy causing many deviations
Look at the configurations on the periodic table on the back cover of the book.
Chapter 4 Section 3 Electron Configurations pages

53. Chapter 4 Section 3 Electron Configurations pages 110-122
PRACTICE
Page 122 #1 & 2
p. 113
1. answer answer 3. answer
Chapter 4 Section 3 Electron Configurations pages

54. Chapter 4 Section 3 Electron Configurations pages 110-122
Section 3 Homework
Chapter 4 Section 3 Electron Configurations pages