Sections 7.4

1
Sections 7.4 7.5 Periodic Properties of Atoms
and Ions
2
Periodic Properties

• In these sections
• Trends in Orbital Energies
• Atomic Size
• Ionization Energy
• Electron Affinity
• Ion Electron Configuration and Size

3
Periodic Properties of the Elements

• All atomic properties depend on energies of
  outermost orbitals.
• Relative energies of outermost orbitals depend on
  their size and their effective nuclear charge.

4
Trends in Orbital Energies
5
Across a period, orbital energies decrease.
6
Why do energies decrease moving left-to-right?
Effective Nuclear Charge Z Z - S
7
General Periodic Trends
Highest Occupied Orbital
smaller, lower energy
larger, high energy
8
Atomic Size What does that mean?
9
Atomic Size Trends
10
Ionization Energy What does that mean?
Atom(g) ? Atom(g) e- ?E
ionization energy
11
Ionization Energy Trends I
12
Ionization Energy Trends II
13
Why the breaks in the line?
14
Electron Affinity What does that mean?
Atom(g) e- ? Atom-(g) ?E electron
affinity
Trends
15
Why is EA sometimes zero?
16
Ion Formation Why do ions have the charges
they do?
17
Cations vs. Anions
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Electron Configurations of Cations
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Transition Metal Cations Lose s electrons first
21
Ion Size
In General Anions are big. Cations are small.
22
Isoelectronic Species