Matter and Measurement

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

• Spdf notation
• Orbital box notation

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Characteristics of Many-Electron Atoms The
Electron-Spin Quantum Number
Name
Symbol
Permitted Values
Property
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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

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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

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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

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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

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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

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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

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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

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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

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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

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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

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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

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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

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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

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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

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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

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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

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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

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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

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PERIODIC TRENDS
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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.
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Trends in Some Key Periodic Atomic Properties
Trends in Atomic Size
Atomic radii of the main-group and transition
elements.
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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.
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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 --gt 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!

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Ionization Energy

• IE energy required to remove an electron from
  an atom in the gas phase.

Mg (g) 738 kJ ---gt Mg (g) e- Mg (g)
1451 kJ ---gt Mg2 (g) e- Mg has 12
protons and only 11 electrons. Therefore, IE for
Mg gt Mg
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Trends in Some Key Periodic Atomic Properties
Trends in Ionization Energy
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Ion Sizes
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.

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Ion Sizes
Forming an anion.

• 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.

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Ion Configurations

• To form cations, always remove electrons of
  highest n value first!
• P Ne 3s2 3p3 - 3e- ---gt P3 Ne 3s2 3p0

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Trends in Ion Sizes
Active Figure 8.15
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Practice Problem 23-10

• Which of the following has the largest radius?
• A) F
• B) N
• C) C
• D) O
• E) Ne

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Practice Problem 23-10 Answer

• Which of the following has the largest radius?
• A) F
• B) N
• C) C
• D) O
• E) Ne

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Practice Problem 23-11

• Which of the following elements has the largest
  ionization energy?
• A) Na
• B) Ne
• C) F
• D) K
• E) Rb

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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

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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

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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

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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)

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Practice Problem 23-13 Answer

• 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)

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Practice Problem 23-14

• Which ion has the smallest radius?
• A) Li
• B) Na
• C) K
• D) Be2
• E) Mg2

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Practice Problem 23-14 Answer

• Which ion has the smallest radius?
• A) Li
• B) Na
• C) K
• D) Be2
• E) Mg2

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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.

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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.

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Practice Problem 23.16

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

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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

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Practice Problem 23.17

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

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Practice Problem 23.17 Answer

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

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Practice Problem 23.18

• Which of the following ions and atoms has the
  largest radius?
• A) Mg
• B) Na
• C) Na
• D) Mg2
• E) Al

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Practice Problem 23.18 Answer

• Which of the following ions and atoms has the
  largest radius?
• A) Mg
• B) Na
• C) Na
• D) Mg2
• E) Al

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Practice Problem 23.19

• Which of the following elements has the greatest
  metallic character?
• A) Mg
• B) Al
• C) Ca
• D) Ba
• E) Cs

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Practice Problem 23.19 Answer

• Which of the following elements has the greatest
  metallic character?
• A) Mg
• B) Al
• C) Ca
• D) Ba
• E) Cs

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Equations

• speed of light wavelength x frequency
• c ? X ? 3.00 x 108 m/s
• E nh? nh(c/?) n positive integer
• Plancks constant(h) 6.626 x 1034 J s
• ?Eatom Eemitted (or absorbed) radiation ?nh?
• Rydberg equation R
• n2 gt n1
• R 1.096776 x 107 m-1
• ?E Efinal Einitial 2.18 x 1018 J
• Ephoton Estate A Estate B h?

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Quantum mechanics
Quantum number Values Total number
n shell/level 1,2,3, 8 n subshells n2 orbitals in a shell
l - subshell/ sublevel 0, 1, n-1 n-1
ml - orbital - l, 0, l 2 l 1 (orbitals in a subshell)
ms - spin ½, -½ 2 possible
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Practice Problem 23-20

• When electrons in helium atoms fall from the 3s
  orbital down to the 1s orbital, how many
  different energies could be released if all
  possible pathways of decreasing energy are
  considered?
• A) 2 B) 4 C) 5
• D) 6 E) 7

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Practice Problem 23-20 Answer

• When electrons in helium atoms fall from the 3s
  orbital down to the 1s orbital, how many
  different energies could be released if all
  possible pathways of decreasing energy are
  considered?
• A) 2 B) 4 C) 5
• D) 6 E) 7

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Practice Problem 23-21

• Of the following four electron configurations,
  which two represent elements that would have
  similar chemical properties? 1. 1s22s22p5 2.
  1s22s22p6
• 3. Ar4s23d104p4 4. Ar4s23d104p5
• A) 1 and 3 B) 1 and 4 C) 2 and 3
• D) 1 and 2 E) 2 and 4

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Practice Problem 23-21 Answer

• Of the following four electron configurations,
  which two represent elements that would have
  similar chemical properties? 1. 1s22s22p5 2.
  1s22s22p6
• 3. Ar4s23d104p4 4. Ar4s23d104p5
• A) 1 and 3 B) 1 and 4 C) 2 and 3
• D) 1 and 2 E) 2 and 4

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Practice Problem 23-22

• The electron configuration for Fe2 is 1s2 2s2
  2p6 3s2 3p6 3d6. Therefore Fe2 is
• A) paramagnetic with two unpaired electrons.
• B) paramagnetic with one unpaired electron.
• C) paramagnetic with three unpaired electrons.
• D) paramagnetic with four unpaired electrons.
• E) diamagnetic.

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Practice Problem 23-22 Answer

• The electron configuration for Fe2 is
• 1s2 2s2 2p6 3s2 3p6 3d6.
• Therefore Fe2 is
• A) paramagnetic with two unpaired electrons.
• B) paramagnetic with one unpaired electron.
• C) paramagnetic with three unpaired electrons.
• D) paramagnetic with four unpaired electrons.
• E) diamagnetic.