(types of substances)

• what is the melting / boiling point of ionic compounds like?

  high because you need significant amounts of energy to overcome the electrostatic forces between the ions and electrons in the lattice.
• when do ionic lattices NOT conduct electricity?

  when solid
• when do ionic lattices conduct electricty?

  when molten, or dissolved in water, the ions in the lattice can move freely so charge can flow.
• what are the bonds like in small covalent molecules?

  small covalent molecules are held together by strong covalent bonds.

  lots of small covalent molecules are held together by weak intermolecular forces.
• why do small covalent molecules have a low melting / boiling point?

  intermolecular forces are weak and easy to break.
• what state are small covalent molecules at room temp?

  liquid or gas
• do small molecules conduct electricty?

  no because they don't contain delocalised electrons.
• why do bigger molecules have higher melting points than smaller molecules?

  bigger molecules attract other molecules with stronger intermolecular forces.
• what is the melting point of giant covalent structures like?


  very high because the strong covalent bonds make them solids at room temperature.
• giant covalent structures exist as 1 large structure or molecule, there are no intermolecular forces.
• what are the properties of diamond?

  • hard
  • high melting point
  • covalent bonds
  • doesn't conduct electricity
• why is diamond hard?

  there are lots of strong covalent bonds.
• what is the structure of diamond?

  each carbon atom in diamond is bonded to 4 other carbon atoms by strong covalent bonds, created a giant covalent structure.
• what is the structure of graphite?

  each carbon atom in graphite is bonded to 3 other carbon atoms by strong covalent bonds, this creates a giant covalent structure.
• why does graphite conduct electricity?

  each carbon atom forms 3 bonds, meaning there is 1 delocalised electron from every carbon atom. This electron can move freely, so graphite is a good electrical conductor.
• why is graphite soft?

  the carbon atoms form layers of hexagonal rings, with weak intermolecular forces keeping the layers together. The layers can easily slide over each other, making graphite very soft.
• what are the uses of graphite?

  pencil lead and lubricants.
• what are the uses of diamond?

  jewelery and cutting tools
• what are the properties of graphite?

  • giant covalent structure
  • conducts electricity
  • soft
• what is the structure of fullerenes?

  molecules of carbons that take up hollow structures. Their structure is usually arranged in hexagonal rings but pentagonal and heptagonal carbon rings can also be found.
• what was the first fullerene to be discovered?

  Buckminsterfullerene
• what structure does buckminsterfullerene have?


  it has a spherical shape and has the formula C60.
• what are the uses of fullerenes?

  catalysts, lubricants, and as vehicles for transporting drugs into our bodies.
• what are carbon nanotubes?

  cyclindrical fullerenes, they are often called molecular wires because they have a tiny diameter but can be incredibly long.
• what are uses of cyclindrical fullerenes?

  in electronics, in nanotechnology, and for strengthening materials (tennis racket frames).
• why does graphene conduct electricity?

  each carbon atom has a delocalised electron. Graphene is a single layer of graphite so it also conducts electricity because of the carbon atoms' delocalised electron.
• how is graphene light but strong?


  graphene has a thickness of 1 atom (1 layer) meaning it's almost 2D, so it's very light. But, the strong covalent bonds between carbon atoms mean that it is also very strong.
• what are the uses of graphene?

  • makes metals stronger without making them much heavier.
  • used in solar panels and batteries.
• what are polymers held together by?

  strong covalent bonds between atoms in molecules and weak intermolecular forces between molecules.
• what state are polymers usually at room temperature?

  Solid
• why do polymers melt easily?

  the intermolecular forces remain less strong than chemical bonds.
• why are pure metals soft and maleable?

  because the ions are arranged in layers, they easily move over each other when a force is applied.
• what are the properties of pure metals?

  • high melting / boiling points
  • soft and malleable