C3: structure and bonding

• Heating or cooling curve

  1. Quick increase in temperature

  2. Flattening out

  3. Increase again

  4. Flattening out again
• Reason for flattening out points

  Change in state occurring (e.g. melting, evaporating)
• Evaporating requires more energy than melting, so the flattening out line is flatter for evaporating</b>
• The particle model has limitations as not everything is a perfect sphere
• Atoms

  Want to have a full outer shell of 8 electrons, either by losing or gaining electrons
• Forming an ion

  1. Lose or gain electrons

  2. Draw electron configuration

  3. Determine charge
• Determining ion charge

  • Group 1 = +1
  • Group 2 = +2
  • Group 3 = +3
  • Group 5 = -3
  • Group 6 = -2
  • Group 7 = -1
• Ionic bonding

  1. Atoms become ions

  2. Electrons donated from one atom to another

  3. Determine molecular formula using diagonal rule
• Ionic compounds

  • Form giant lattices
  • Have high melting and boiling points due to strong electrostatic forces
  • Conduct electricity as liquids or in solution but not as solids
• Higher charge on ions

  Higher electrostatic forces, higher melting/boiling points
• Covalent bonding

  • Occurs between two non-metals
  • Electrons are shared between atoms, not transferred
• Atoms want a full outer shell of 8 electrons, they can achieve this by losing or gaining electrons
• Ionic compounds form giant lattices with high melting/boiling points due to strong electrostatic forces
• Ionic compounds conduct electricity as liquids or in solution, but not as solids
• Higher charge on ions results in higher electrostatic forces and higher melting/boiling points
• Covalent bonding occurs between two non-metals, with electrons shared between atoms
• Double bond


  Each line represents one bonding pair of electrons
• Covalent compounds

  • Have weak or no forces of attraction between molecules
  • Have low melting and boiling points
  • Do not conduct electricity
• Covalent structures


  Can be giant, not just simple
• Allotropes of carbon

  • Graphite - has delocalized electrons, conducts electricity, acts as a lubricant
  • Diamond - has 4 bonds per carbon, incredibly strong and hard, does not conduct electricity
  • Fullerenes - have delocalized electrons, conduct electricity, high melting/boiling point
  • Graphene - one-atom thick sheet of graphite, acts as a superconductor
• Metallic bonding

  • Positive metal ions with delocalized electrons in between
  • Allows metals to conduct electricity and heat
  • Makes metals malleable and ductile
• Alloys


  • Mixtures of metals with different properties than pure metals
  • Can be stronger, have higher melting/boiling points
• Common alloys

  • Steel
  • Brass