Topic: Chemical Bonding

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Topic Chemical Bonding
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chemical bond

• A chemical bond is a electrostatic force between
  atoms (caused by electrons attracting to the
  positive nucleus of another atom)

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Why do atoms form bonds?
How do atoms form chemical bonds?
By gaining, losing, or sharing electrons

• To attain a noble gas configuration

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A B ? AB

• When a bond formed energy is released
  reaction is exothermic

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Breaking a Bond Absorbs Energy (endothermic)!
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When a chemical bond is formed, PE is released,
the bond becomes more stable

• You have to put energy in to brake a chemical
  bond, so PE increases and the overall system
  becomes less stable

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Ionic Bonding

• Occurs between?
• (type of elements)
• Electrons
• (shared or transferred?)

• Metals and nonmetals
• Transferred, metal loses, nonmetal gains

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electron transferred from Na to Cl
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The more Na and Cl2, the larger the resulting
NaCl crystal -just keep adding on to it
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Structure of Ionic Compounds

• Ions form crystal lattice
• regular 3-D pattern or array
• Ions held in fixed positions (solid state)

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Ionic Bonding

• Type of structure?
• Properties

• Crystal Lattice
• High Boiling Point, High Melting Point, Hard,
  Brittle, Conduct electricity if melted or in
  solution (dissolved in water)

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NaCl has its own unique properties
lattice structure ?
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Metallic Bonding

• Occurs between?
• (type of elements)
• Electrons
• (shared or transferred?)

• Metals
• Mobile sea of electrons

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Metallic Bonding

• Type of structure?
• Properties

• Crystal Lattice
• High Boiling Point, High Melting Point, Hard,
  Good Conductors electricity

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Covalent Bonding

• Occurs between?
• (type of elements)
• Electrons
• (shared or transferred?)

• Nonmetals only
• shared

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Covalent Bonding

• Type of structure?
• Properties

• Molecules held together by IMF (intermolecular
  forces)
• Low Boiling Point, Low Melting Point, soft, poor
  conductors of electricity

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Identify Bond Type from Formula
Covalent
Covalent
Metallic
Ionic
Covalent
Covalent
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So what? Why is structure so important?
Structure determines physical properties!