1. Classwork: Standard: 2e terms: 135 Article: 136 Mastering concept: 146(57-64) Practice Problems: 139(18-22), 141(23) Homework: Cornell notes: 5.3 sec. assessment: 141(24-26)

2. Section 5-3
Section 5.3 Electron Configuration
Apply the Pauli exclusion principle, the aufbau principle, and Hund's rule to write electron configurations using orbital diagrams and electron configuration notation.
Define valence electrons, and draw electron-dot structures representing an atom's valence electrons.
electron: a negatively charged, fast-moving particle with an extremely small mass that is found in all forms of matter and moves through the empty space surrounding an atom's nucleus

3. Section 5-3 electron configuration aufbau principle
Section 5.3 Electron Configuration (cont.)
electron configuration
aufbau principle
Pauli exclusion principle
Hund's rule
valence electrons
electron-dot structure
A set of three rules determines the arrangement in an atom.

4. Section 5-3
Ground-State Electron Configuration
The arrangement of electrons in the atom is called the electron configuration.
The aufbau principle states that each electron occupies the lowest energy orbital available.

5. Section 5-3
Ground-State Electron Configuration (cont.)

6. Section 5-3
Ground-State Electron Configuration (cont.)
The Pauli exclusion principle states that a maximum of two electrons can occupy a single orbital, but only if the electrons have opposite spins.
Hund’s rule states that single electrons with the same spin must occupy each equal-energy orbital before additional electrons with opposite spins can occupy the same energy level orbitals.

7. Section 5-3
Ground-State Electron Configuration (cont.)

8. Section 5-3
Ground-State Electron Configuration (cont.)
Noble gas notation uses noble gas symbols in brackets to shorten inner electron configurations of other elements.

9. Section 5-3
Ground-State Electron Configuration (cont.)
The electron configurations (for chromium, copper, and several other elements) reflect the increased stability of half-filled and filled sets of s and d orbitals.

10. Section 5-3
Valence Electrons
Valence electrons are defined as electrons in the atom’s outermost orbitals—those associated with the atom’s highest principal energy level.
Electron-dot structure consists of the element’s symbol representing the nucleus, surrounded by dots representing the element’s valence electrons.

11. Section 5-3
Valence Electrons (cont.)

12. Electron Configuration Rules
Aufbau: electrons fill lowest Energy level 1st
Pauli: only 2 electrons may share an atomic orbital, and only when they have opposite spins
Hunds: single electrons with the same spin must occupy each equal energy orbital before additional electrons with opposite spins can enter the same orbitals

13. Sub-shell
#Orbits
# Electrons s 1 2 p 3 6 d 5 10 f 7 14

15. Mastering Concepts: 146(57-64)
Electron Configurations

16. 57. Explain the meaning of the aufbau principle as it applies to atoms with many electrons. (5.3) The aufbau principle describes the sequence in which an atom’s orbitals are filled with electrons.

17. 58. In what sequence do electrons fill the atomic orbitals related to a sublevel? (5.3) Each orbital must contain a single electron before any orbital contains two electrons.

23. 59. Why must the two arrows within a single block of an orbital diagram be written in opposite (up and down) directions? (5.3) Two electrons occupying a single atomic orbital must have opposite spins.

24. 60. How does noble-gas notation shorten the process of writing an element’s electron configuration? (5.3) The noble-gas notation uses the bracketed symbol of the preceding noble gas in the periodic table to represent an atom’s inner electrons. S1 1 Ne
3 Na 4
[Ne] 3S1

25. 61. What are valence electrons
61. What are valence electrons? Valence electrons are the electrons in an atom’s outermost orbitals

26. Valence Electrons

27. 61. How many of a magnesium atom’s 12 electrons are valence electrons

28. 62. Light is said to have a dual wave-particle nature
62. Light is said to have a dual wave-particle nature. What does this statement mean? (5.3) Light exhibits wavelike behavior in some situations and particlelike behavior in others.

29. 63. Describe the difference between a quantum and a photon. (5
63. Describe the difference between a quantum and a photon. (5.3) A quantum is the minimum amount of energy that can be lost or gained by an atom, while a photon is a particle of light that carries a quantum of energy.

30. 64. How many electrons are shown in the electron-dot structures of the following elements? (5.3)
Carbon 4
b. Iodine 7
c. Calcium 2
d. Gallium 3

31. Shorthand Configuration
neon's electron configuration (1s22s22p6) B
third energy level
[Ne] 3s1 C
one electron in the s orbital D
Valence electrons
– Tedious to keep copying the configurations of the filled inner subshells
– Simplify the notation by using a bracketed noble gas symbol to represent the configuration of the noble gas from the preceding row
– Example: [Ne] represents the 1s22s22p6 electron configuration of neon (Z = 10) so the electron configuration of sodium
(Z = 11), which is 1s22s22p63s1, is written as [Ne]3s1
– Electrons in filled inner orbitals are closer and are more tightly bound to the nucleus and are rarely involved in chemical reactions
orbital shape
Na = [1s22s22p6] 3s1
electron configuration

32. Practice Problems: 139 (18-22)
18. Write ground state electron configurations for the following elements.
Bromine (Br)
Strontium (Sr)
Antimony (Sb)
Rhenium (Re)
Terbium (Tb)
Titanium (Ti)

33. Practice Problems: 139 (18-22)
18. Write ground state electron configurations for the following elements.
Bromine (Br)
bromine (35 electrons): [Ar]4s23d104p5

34. Practice Problems: 139 (18-22)
18. Write ground state electron configurations for the following elements. b.Strontium (Sr) strontium (38 electrons): [Kr]5s2

35. Practice Problems: 139 (18-22)
18. Write ground state electron configurations for the following elements. c. Antimony (Sb) antimony (51 electrons): [Kr]5s24d105p3

36. Practice Problems: 139 (18-22)
18. Write ground state electron configurations for the following elements. d. Rhenium (Re) rhenium (75 electrons): [Xe]6s24f145d5

37. Practice Problems: 139 (18-22)
18. Write ground state electron configurations for the following elements. e. Terbium (Tb) terbium (65 electrons): [Xe]6s24f9

38. Practice Problems: 139 (18-22)
18. Write ground state electron configurations for the following elements. f. Titanium (Ti) titanium (22 electrons): [Ar]4s23d2

39. Practice Problems: 139 (18-22)
19. How many electrons are in orbitals related to the third energy level of a sulfur atom? 20. How many electrons occupy p orbitals in a chlorine atom? 21. What element has the following ground state electron configuration? [Kr]5s24d105p1 22. What element has the following ground state electron configuration? [Xe]6s2

40. Practice Problems: 139 (18-22)
19. How many electrons are in orbitals related to the third energy level of a sulfur atom? Sulfur (16 electrons) has the electron configuration [Ne]3s23p4. 6 electrons are in orbitals related to the third energy level of the sulfur atom.

41. Practice Problems: 139 (18-22)
20. How many electrons occupy p orbitals in a chlorine atom? Chlorine (17 electrons) has the electron configuration [Ne]3s23p5, or 1s22s22p63s23p5. 11 electrons occupy p orbitals in a chlorine atom.

42. Practice Problems: 139 (18-22)
21. What element has the following ground state electron configuration? [Kr]5s24d105p1 indium (In)

43. Practice Problems: 139 (18-22)
22. What element has the following ground state electron configuration? [Xe]6s2 barium (Ba)

44. Practice Problems: 141(23)
23. Draw electron dot structures for atoms of the following elements.
Magnesium
Sulfur
Bromine
Rubidium
Thallium
Xenon

45. Practice Problems: 141(23)
Magnesium

46. . Mg . Practice Problems: 141(23)
23. Draw electron dot structures for atoms of the following elements.
Magnesium
. Mg .

47. Practice Problems: 141(23)
B. Sulfur

48. Practice Problems: 141(23)
23. Draw electron dot structures for atoms of the following elements. B. Sulfur

49. Practice Problems: 141(23)
C. Bromine

50. Practice Problems: 141(23)
23. Draw electron dot structures for atoms of the following elements. C. Bromine

51. Practice Problems: 141(23)
d. Rubidium

52. Practice Problems: 141(23)
23. Draw electron dot structures for atoms of the following elements. d. Rubidium

53. Practice Problems: 141(23)
E. Thallium

54. Practice Problems: 141(23)
23. Draw electron dot structures for atoms of the following elements.
E. Thallium

55. Practice Problems: 141(23)
F. Xenon

56. Practice Problems: 141(23)
23. Draw electron dot structures for atoms of the following elements. F. Xenon

57. write e configuration of K & Ar and compare
same except (K) has extra 4s1
Why Ar is stable?
It is a noble gas and has 8e.
How K can achieve noble gas configuration