Periodic Trends

1
Periodic Trends

• The Periodic Table

2
Periodic Properties

• Atomic Radius
• ½ the distance between
• two identical atoms
• bonded together

• Ionization Energy
• Energy required to
• remove one e- from a
• neutral atom.

3
Periodic Properties

• Electron Affinity
• Attraction for additional electrons

• Electronegativity
• Pull an atom has on electrons when bonded to
  another atom

4
A. Atomic Radius

• Atomic Radius

1. Increases to the LEFT and DOWN

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A. Atomic Radius

• Why larger going down?
• Adding energy levels
• Shielding - core e- block the attraction between
  the nucleus and the valence e-

6
A. Atomic Radius

• Why smaller to the right?
• Increased nuclear charge (i.e. more protons in
  nucleus) without more shielding pulls e- in
  tighter

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A. Atomic Radius
Nucleus not strong enough to pull valence e- in
tight
Stronger nucleus pulls valence e- in tight
8
A. Atomic Radius

• Atomic Radius

K
Na
Li
Ar
Ne
9
B. Ionic Radius

• Ionic Radius

• Cations ()
• lose e-
• smaller

• Anions ()
• gain e-
• larger

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B. Ionic Radius

• Ionic Radius

• Tug of War between positive nucleus and
  negative electrons.

• Cations nucleus is stronger
• Anions electrons are stronger

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Examples

• Which atom has the larger radius?

• Be or Ba
• Ca or Br

Ba Ca
12
Examples

• Which particle has the larger radius?

• S or S2-
• Al or Al3

S2- Al
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C. Ionization Energy

• First Ionization Energy energy needed to remove
  ONE electron.

He
Ne
Ar
Na
Li
K
14
C. Ionization Energy

• First Ionization Energy

1. Increases UP and to the RIGHT

15
C. Ionization Energy

• Why opposite of atomic radius?
• In small atoms, e- are close to the nucleus where
  the attraction is stronger it takes a lot of
  energy to strip an e- away!
• Why small jumps within each group?
• Stable e- configurations dont want to lose e-

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C. Ionization Energy

1. Successive Ionization Energies

1. Large jump in I.E. occurs when a CORE e- is
   removed after all valence e- have been removed.

• Mg 1st I.E. 736 kJ
• 2nd I.E. 1,445 kJ
• Core e- 3rd I.E. 7,730 kJ

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C. Ionization Energy

1. Successive Ionization Energies

1. Large jump in I.E. occurs when a CORE e- is
   removed after all valence e- have been removed.

• Al 1st I.E. 577 kJ
• 2nd I.E. 1,815 kJ
• 3rd I.E. 2,740 kJ
• Core e- 4th I.E. 11,600 kJ

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Examples

• Which atom has the higher 1st I.E.?

• N or Bi
• Ba or Ne

N Ne
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D. Electron Affinity

• Electron Affinity

1. Increases UP and to the RIGHT

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D. Electron Affinity

• Why smaller going down?
• e- further from the nucleus
• Greater shielding additional e- feel the
  attraction from the nucleus less.
• Why greater to the right?
• Higher nuclear charge without greater shielding
  stronger nucleus has a greater attraction for e-
  (atoms tend to make anions)

21
Examples

• Which atom has the higher e- affinity?

• K or Br
• F or I

Br F
22
E. Electronegativity

• Electronegativity

1. Increases UP and to the RIGHT

23
Examples

• If the following atoms were bonded together,
  which would have the higher electronegativity?

• P or S
• Se or O

S O
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F. Melting/Boiling Point

• Melting/Boiling Point

• Highest in the middle of a period.