Bonding, strucuture + properteis

• The three states of matter


  Solid, liquid and gas

  
• Melting and freezing


  Take place at the melting point
• Boiling and condensing


  Take place at the boiling point
• Particle theory


  • Can help to explain melting, boiling, freezing and condensing
  • The amount of energy needed to change state depends on the strength of the forces between the particles
  • The nature of the particles involved depends on the type of bonding and the structure of the substance
  • The stronger the forces between the particles the higher the melting point and boiling point of the substance
• Limitations of the simple particle model include that there are no forces, all particles are represented as spheres, and the spheres are solid
• State symbols


  Solid (s), liquid (l), gas (g), aqueous (aq)
• Ionic compounds


  • Have regular structures (giant ionic lattices)
  • Have strong electrostatic forces of attraction in all directions between oppositely charged ions
  • Have high melting and boiling points
  • Conduct electricity when melted or dissolved in water, but not when solid
• Small molecules


  • Usually gases or liquids with low boiling and melting points
  • Have weak intermolecular forces between the molecules
  • Larger molecules have higher melting and boiling points
  • Don't conduct electricity
• Polymers


  • Have very large molecules
  • Atoms in the polymer molecules are linked by strong covalent bonds
  • Intermolecular forces between polymer molecules are relatively strong, so they are solids at room temperature
• Giant covalent structures


  • Are solids with very high melting points
  • All atoms are linked by strong covalent bonds that must be overcome to melt or boil
• Giant covalent structures


  • Diamond, graphite, silicon dioxide
• Metals


  • Have giant structures of atoms with strong metallic bonding
  • Most have high melting and boiling points
  • The layers of atoms can slide over each other, so metals can be bent and shaped
• Alloys


  • Made from 2 or more different types of metals
  • The different sized atoms distort the layers in the structure, making it harder for them to slide over each other, so alloys are harder than pure metals
• Metals as conductors


  • Good conductors of electricity because the delocalised electrons carry electrical charge
  • Good conductors of thermal energy because energy is transferred by the delocalised electrons