CHAPTER 8 Atomic Electron Configurations and Chemical Periodicity

1. CHAPTER 8 Atomic Electron Configurations and Chemical Periodicity Outline-Collect homework-Review-Trends -Ions

2. Review • Spdf notation • Orbital box notation

3. principal n positive integers(1,2,3,…) orbital energy (size) angular momentum l integers from 0 to n-1 orbital shape (The l values 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 Characteristics of Many-Electron Atoms: The Electron-Spin Quantum Number Name Symbol Permitted Values Property

5. Practice Problem 23-1 • Consider this set of quantum numbers: n = 3, ℓ = 2, mℓ = -1, ms = +½ The maximum number of electrons in an atom which can share the above set of quantum numbers is A) 1 B) 14 C) 3 D) 10 E) none of the above

6. Practice Problem 23-1 Answer • Consider this set of quantum numbers: n = 3, ℓ = 2, mℓ = -1, ms = +½ The maximum number of electrons in an atom which can share the above set of quantum numbers is A) 1 B) 14 C) 3 D) 10 E) none of the above

7. Practice Problem 23-2 • An atom in its ground state contains 30 electrons. How many of these are in sublevels with ℓ = 2? A) 2 B) 4 C) 6 D) 8 E) 10

8. Practice Problem 23-2 Answer • An atom in its ground state contains 30 electrons. How many of these are in sublevels with ℓ = 2? A) 2 B) 4 C) 6 D) 8 E)10

9. Practice Problem 23-3 What are the possible values for the angular momentum quantum number ℓ ? A) integers from -ℓ to 0 to +ℓ B) 1, 2, 3, etc. C) 2, 4, 6, etc. D) +½ , -½ E) integers from 0 to n - 1

10. Practice Problem 23-3 Answer • What are the possible values for the angular momentum quantum number (ℓ)? A) integers from -ℓ to 0 to +ℓ B) 1, 2, 3, etc. C) 2, 4, 6, etc. D) +½ , -½ E) integers from 0 to n - 1

11. Practice Problem 23-4 • The electron configuration of the outermost electrons of atoms of the halogen group is: A) ns2np7 B) ns1 C) ns2np5 D) ns2np6(n-1)d7 E) ns2np6

12. Practice Problem 23-4 Answer • The electron configuration of the outermost electrons of atoms of the halogen group is: A) ns2np7 B) ns1 C) ns2np5 D) ns2np6(n-1)d7 E) ns2np6

13. Practice Problem 23-5 • The electronic configuration of the element whose atomic number is 26 is: A) 1s2 2s2 2p6 3s2 3p6 4s0 3d8 B) 1s2 2s2 2p6 3s2 3p6 3d6 4s2 C) 1s2 2s2 2p6 3s2 3p6 4s2 3d6 D) 1s2 2s2 2p6 3s2 3p6 4s2 3d4 4p2 E) none of the above

14. Practice Problem 23-5 Answer • The electronic configuration of the element whose atomic number is 26 is: A) 1s2 2s2 2p6 3s2 3p6 4s0 3d8 B) 1s2 2s2 2p6 3s2 3p6 3d6 4s2 C) 1s2 2s2 2p6 3s2 3p6 4s2 3d6 D) 1s2 2s2 2p6 3s2 3p6 4s2 3d4 4p2 E) none of the above

15. Practice Problem 23-6 • The set of quantum numbers that correctly describes an electron in a 3p orbital is A) n = 3; ℓ = 0; mℓ = 0; ms = 0 B) n = 3; ℓ = 2; mℓ = -2, -1, 0, 1, or 2; ms = +½ or -½ C) n = 3; ℓ = 1; mℓ = -1, 0, or 1; ms = +½ or -½ D) n = 4; ℓ = 0; mℓ = -1 ,0, or 1; ms = +½ or -½ E) none of the above

16. Practice Problem 23-6 Answer • The set of quantum numbers that correctly describes an electron in a 3p orbital is A) n = 3; ℓ = 0; mℓ = 0; ms = 0 B) n = 3; ℓ = 2; mℓ = -2, -1, 0, 1, or 2; ms = +½ or -½ C) n = 3; ℓ = 1; mℓ = -1, 0, or 1; ms = +½ or -½ D) n = 4; ℓ = 0; mℓ = -1 ,0, or 1; ms = +½ or -½ E) none of the above

17. Practice Problem 23- 7 • An atom in its ground state contains 18 electrons. How many of these are in orbitals with mℓ = 0? A) 2 B) 4 C) 6 D) 8 E) 10

18. Practice Problem 23-7 Answer • An atom in its ground state contains 18 electrons. How many of these are in orbitals with mℓ = 0? A) 2 B) 4 C) 6 D) 8 E) 10

19. Practice Problem 23-8 • The configuration for the six outer electrons in ground state oxygen atoms is A) 2s3 2p3-1 B) 2p6 C) 2s2 2p-12 2p02 D) 2s2 2p-12 2p01 2p11 E) 2s4 2p2-1

20. Practice Problem 23-8 Answer • The configuration for the six outer electrons in ground state oxygen atoms is A) 2s3 2p3-1 B) 2p6 C) 2s2 2p-12 2p02 D) 2s2 2p-12 2p01 2p11 E) 2s4 2p2-1

21. Practice Problem 23-9 • Which of the following is the electron configuration for chromium, element 24? A) 1s2 2s2 2p6 3s2 3p6 4s2 B) 1s2 2s2 2p6 3s2 3p6 4s2 3d4 C) 1s2 2s2 2p6 3s2 3p6 3d6 D) 1s2 2s2 2p6 3s2 3p6 4s1 3d5 E) 1s2 2s2 2p6 3s2 3p6 4s2 3d1 3d1

22. Practice Problem 23-9 Answer • Which of the following is the electron configuration for chromium, element 24? A) 1s2 2s2 2p6 3s2 3p6 4s2 B) 1s2 2s2 2p6 3s2 3p6 4s2 3d4 C) 1s2 2s2 2p6 3s2 3p6 3d6 D) 1s2 2s2 2p6 3s2 3p6 4s1 3d5 E) 1s2 2s2 2p6 3s2 3p6 4s2 3d1 3d1

25. PERIODIC TRENDS

26. Trends in Some Key Periodic Atomic Properties: Trends in Electron Affinity • Atomic and ionic size • # electrons • # shells – • Larger orbitals, • -electrons held less tightly • Effective nuclear charge • When higher: Electrons held • more tightly Electron affinity: energy involved when an atom gains an electron to form an anion.

27. Trends in Some Key Periodic Atomic Properties: Trends in Atomic Size Atomic radii of the main-group and transition elements.

28. The Effect of Nuclear Charge (Zeffective) The Effect of Electron Repulsions (Shielding) Characteristics of Many-Electron Atoms: Electrostatic Effects and the Splitting of Energy Levels Factors Affecting Atomic Orbital Energies Higher nuclear charge lowers orbital energy (stabilizes the system) by increasing nucleus-electron attractions. Additional electron in the same orbital An additional electron raises the orbital energy through electron-electron repulsions. Additional electrons in inner orbitals Inner electrons shield outer electrons more effectively than do electrons in the same sublevel.

29. Effective Nuclear Charge, Z* • Z* is the nuclear charge experienced by the outermost electrons. • Z* increases across a period owing to incomplete shielding by inner electrons. • The 2s electron PENETRATES the region occupied by the 1s electron. • 2s electron experiences a higher positive charge than expected. • Estimate Z* by --> [ Z - (# inner electrons) ] • Charge felt by 2s e- in Li Z* = 3 - 2 = 1 • Be Z* = 4 - 2 = 2 • B Z* = 5 - 2 = 3 and so on!

30. Ionization Energy IE = energy required to remove an electron from an atom in the gas phase. Mg (g) + 738 kJ ---> Mg+ (g) + e- Mg+ (g) + 1451 kJ ---> Mg2+ (g) + e- Mg+ has 12 protons and only 11 electrons. Therefore, IE for Mg+ > Mg

31. Trends in Some Key Periodic Atomic Properties: Trends in Ionization Energy

32. + + Li , 78 pm 2e and 3 p Ion Sizes • CATIONS are SMALLER than the atoms from which they come. • The electron/proton attraction has gone UP and so size DECREASES. Forming a cation. Li,152 pm 3e and 3p

33. - - F, 71 pm F , 133 pm 9e and 9p 10 e and 9 p Ion Sizes • 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. Forming an anion.

34. Ion Configurations To form cations, always remove electrons of highest n value first! P [Ne] 3s2 3p3 - 3e- ---> P3+ [Ne] 3s2 3p0

35. Trends in Ion Sizes Active Figure 8.15

36. Practice Problem 23-10 • Which of the following has the largest radius? A) F B) N C) C D) O E) Ne

37. Practice Problem 23-10 Answer • Which of the following has the largest radius? A) F B) N C) C D) O E) Ne

38. Practice Problem 23-11 • Which of the following elements has the largest ionization energy? A) Na B) Ne C) F D) K E) Rb

39. Practice Problem 23-11 Answer • Which of the following elements has the largest ionization energy? A) Na B) Ne C) F D) K E) Rb

40. Practice Problem 23-12 • Which of the following has the greatest electron affinity (most negative value)? A) Cl B) K C) He D) Na E) Rb

41. Practice Problem 23-12 Answer • Which of the following has the greatest electron affinity (most negative value)? A) Cl B) K C) He D) Na E) Rb

42. Practice Problem 23-13 • In the periodic table, the most nonmetallic elements will be found A) at the top of Group 3A (13) B) at the top of Group 1A (1) C) at the top of Group 7A (17) D) at the bottom of Group 1A (1) E) at the bottom of Group 7A (17)

43. Practice Problem 23-13Answer • In the periodic table, the most nonmetallic elements will be found A) at the top of Group 3A (13) B) at the top of Group 1A (1) C) at the top of Group 7A (17) D) at the bottom of Group 1A (1) E) at the bottom of Group 7A (17)

44. Practice Problem 23-14 • Which ion has the smallest radius? A) Li+ B) Na+ C) K+ D) Be2+ E) Mg2+

45. Practice Problem 23-14 Answer • Which ion has the smallest radius? A) Li+ B) Na+ C) K+ D) Be2+ E) Mg2+

46. Practice Problem 23-15 • Which of the following statements about periodic properties is incorrect? A) Both electron affinity and ionization energy decrease down a group. B) Atomic size increases to the right across a period. C) Ionization energy increases to the right across a period. D) Atomic size increases down a group. E) Electron affinity increases to the right across a period.

47. Practice Problem 23.15 Answer • Which of the following statements about periodic properties is incorrect? A) Both electron affinity and ionization energy decrease down a group. B) Atomic size increases to the right across a period. C) Ionization energy increases to the right across a period. D) Atomic size increases down a group. E) Electron affinity increases to the right across a period.

48. Practice Problem 23.16 • Which of the following elements has the greatest ionization energy? A) Ga B) As C) K D) Pb E) Na

49. Practice Problem 22.16 Answer • Which of the following elements has the greatest ionization energy? A) Ga B) As C) K D) Pb E) Na

50. Practice Problem 23.17 • Which of the following elements has the greatest electron affinity? A) Rb B) Ca C) Li D) Na E) I