Chemical Bonding Ionic Bonding

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Chemical BondingIonic Bonding

• Why and How Atoms Stick to each other

2
Chemical Bonding

• Potential Energy Lowering
• Types of Bonds
• Ionic
• Covalent
• Metallic
• Bond Polarity - How Ionic Is It?

3
More Chemical Bonding

• Lewis Structures for Covalent Bonding
• Formal Charge - Selecting the best Lewis
  Structure
• Resonance
• Coordinate Covalent Bonding

4
Lowering Potential Energy

• Rock with Higher Potential (Stored ) Energy -gt

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Lowering Potential Energy

• Converts Potential Energy to Kinetic when it
  falls to lower level

Energy Release
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Bond Formation Lowering Potential Energy

• Na(s) 1/2 Cl2(g)

Na(s) 1/2 Cl2(g)
Energy Release
NaCl(s)
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Ionic Bond

• Transfer of electron(s) from metal to nonmetal

e- e-
e- e-
e-
e-
Na
e- e-
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Ionic Bond

• Transfer of electron(s) from metal to nonmetal
• Resulting Ions with - Charge Attract

-
e- e-

e- e-
e- e-
Na
e- e-
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Ionic Bond

• Coming together of Ions to make Crystal lowers
  potential energy

Na
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Ionic Bond

• Energy Released forming Crystal called Lattice
  Energy

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Net Energy Change - Remember Hesss Law?
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Net Energy Change - Remember Hesss Law?
107.8 kJ
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Net Energy Change - Remember Hesss Law?
495.4 kJ
107.8 kJ
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Net Energy Change - Remember Hesss Law?
Na(g) e- Cl (g)
121.3 kJ
495.4 kJ
107.8 kJ
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Net Energy Change - Remember Hesss Law?
Na(g) e- Cl (g)
121.3 kJ
-348.8 kJ
495.4 kJ
107.8 kJ
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Net Energy Change - Remember Hesss Law?
Na(g) e- Cl (g)
121.3 kJ
-348.8 kJ
495.4 kJ
107.8 kJ
-787 kJ
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Net Reaction
Net ?H -411 kJ
Exothermic Reaction
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Why Na

• Na 496 kJ -gt Na
• Not much energy needed
• Na 4563 kJ -gt Na2
• Too Much Energy to Remove Core e-
• Na e- -gt Na- 53 kJ
• Not much energy released

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Why Cl-?

• Cl e- -gt Cl- 348 kJ
• Exothermic
• Cl anion formation much more exothermic than Na
  anion
• Cl 1251 kJ -gt Cl e-
• Endothermic

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Net Energy Change - Remember Hesss Law?
Na(g) e- Cl (g)
-348.8 kJ
-53 kJ for Na ? Na-
495.4 kJ
1255 kJ for Cl?Cl
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Why Mg2?

• Mg 737 kJ -gt Mg
• Mg 1450 kJ -gt Mg2
• Mg2 7731 kJ -gt Mg3
• Too Much Energy needed to Remove Core e-
• Mg e- 230 kJ -gt Mg-

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Periodic Table
Metals Low IE and eA
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Periodic Table
Nonmetals High IE and eA
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Ionic Bond

• Metals form Cations ()
• Low IE gt Little E needed to remove e-
• Low eA gt Little E lost when gaining e-
• Nonmetals form Anions (-)
• High IE gt Lots of E needed to remove e-
• High eA gt Lots of E lost when gaining e-

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Octet Rule

• Octet Rule
• when forming bonds, atoms tend to gain, lose or
  share electrons so the outer s and p orbitals
  have 8 e-
• Cl has 7 valence e-
• It tends to gain 1 e-, giving it a total of 8

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Octet Rule

• Octet Rule
• when forming bonds, atoms tend to gain, lose or
  share electrons so the outer s and p orbitals
  have 8 e-
• S has 6 valence e-
• It tends to ?

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Octet Rule

• Octet Rule
• when forming bonds, atoms tend to gain, lose or
  share electrons so the outer s and p orbitals
  have 8 e-
• Ca has 2 valence e-
• It tends to ?

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Octet Rule

• Octet Rule
• when forming bonds, atoms tend to gain, lose or
  share electrons so the outer s and p orbitals
  have 8 e-
• Exceptions

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Ionic Bond

• Representative Elements
• Gain or Lose Valence (s and p) e-
• e.g., Na, Mg2, Al3, O-2
• Transition Elements
• Can Lose p, then s, then some d e-
• e.g. Pb2, 4, Fe2, 3
• Half and Completely Full d very stable

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Ionic Bond

• and - charges balance
• e.g. NaCl
• MgCl2
• Al2O3

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Ionic Bond

• and - charges balance
• CaxSy

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Ionic Bond

• and - charges balance
• CaS
• AlxCly

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Ionic Bond

• and - charges balance
• CaS
• AlCl3
• GaxOy

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Ionic Bond

• and - charges balance
• CaS
• AlCl3
• Ga2O3

35
Lewis Symbol

• Used to represent an Atoms Valence e-
• Valence e- shown as dots on 4 sides of element
  symbol
• e.g

- Helpful in drawing Lewis Structures
36
Ionic Bonding

• Potential Energy Lowering
• Bond Formation Exothermic
• Types of Bonds
• Ionic
• Metal Nonmetal
• Transfer of e-(s) from Metal to Nonmetal

37
Ionic Bonding

• Potential Energy Lowering
• Bond Formation Exothermic
• Types of Bonds
• Ionic
• Large Difference between IE and eA of 2 elements
• Octet Rule - Atoms tend to have filled s p
  orbitals when bonding

38
Chemical Bonding

• Why and How Atoms Stick to each other