allotropes of carbon

• What are allotropes?

  Different structural forms of the same element in the same physical state.
• What are the 3 main properties of diamond?

  1. It has a giant covalent structure made up of carbon atoms that each form four covalent bonds which makes diamond really strong.

  
  

  2) It has a high melting point because the covalent bonds take a lot of energy to break.

  
  

  3) It doesn't conduct electricity because no free electrons or ions.
• What does each carbon atom form in graphite?

  Each carbon atom forms three covalent bonds with three other carbon atoms, forming layers of hexagonal rings.
• Are there covalent bonds between the layers in graphite? What affect does this have on the properties of graphite?

  No - this means that the layers are free to slide over each other, making graphite soft and slippery.
• True or false: graphite is an ideal lubricant.

  True.
• Why does graphite have a high melting point?

  It takes a great deal of energy to break the covalent bonds so graphite has high melting and boiling point.
• Graphite can conduct electricity and thermal energy - why is this?

  Only three out of each of carbon's four outer electrons are used in bonds, so each carbon atom has one electron that is delocalised (free) and can move around.
• What is graphene?

  A single layer of graphite, one atom thick, making it a 2D compound.
• What is the structure of graphene?

  It is a sheet of carbon atoms joined together in hexagons.
• What makes graphene strong?

  The network of covalent bonds.
• Why can graphene be added to composite materials?

  Because its very light so it can improve its strength without adding much weight.
• Why does graphene have potential of being used in electronics?

  Because it contains delocalised electrons so can conduct electricity through the whole structure.
• What are fullerenes?

  They are molecules of carbon shaped like closed tubes or hollow balls.
• How are fullerenes arranged?

  The structure of fullerenes is based on hexagonal rings of carbon atoms but they may also contain rings with five (pentagons) or seven (heptagons) carbon atoms.
• What was the first fullerene to be discovered?

  Buckminsterfullerene - this has a molecular formula of C60 and forms a hollow sphere containing 20 hexagons and 12 pentagons.
• What can fullerenes be used for? Give 3 examples.

  1. They could be used to ''cage'' other molecules which could deliver drugs into our bodies.

  2. They have a huge surface area so they could help make great industrial catalysts - individual catalyst molecules could be attached to the fullerenes.

  3. Fullerenes also make great lubricant.
• What structure can fullerenes form?

  Nanotubes - tiny carbon cylinders.
• What are nanotubes and why are they useful?

  Nanotubes are cylindrical fullerenes with very high length to diameter ratios. Their properties make them useful for nanotechnology, electronics and materials.
• What are some properties of nanotubes?

  1. They can conduct electricity and thermal energy.

  2. They have high tensile strength (don't break when stretched).
• Where can nanotubes be used?

  Can be used in electronics or to strengthen materials without adding much weight e.g. In tennis racket frames.