graphenes and fullerenes

• Name four types of giant covalent substances?

  diamond, graphite, graphene, carbon nanotubes
• What are allotropes?

  substances made of the same element, but with different arrangements of atoms
• How many bonds form between each carbon atom in :

  1. diamond
  2. Graphite
  3. graphene
  4. carbon nanotubes

  1)4

  2)3

  3)3

  4)3
• What is the maximum number of bonds that carbon atoms can make, and why?

  4 they are in group 4 so have 4 electrons on the outer shell that they can share
• How is the strength of covalent bonds different to intermolecular bonds?

  they are much stronger, so take more energy to break
• Explain why diamond has a very high melting point?

  Each carbon atom forms 4 strong covalent bonds with other atoms. there are many strong covalent bonds in total, taking lots of energy to break
• Explain why diamond is not a good conductor of electricity?

  All 4 electrons in each carbon atom are used to form covalent bonds. There are no delocalised electrons, so they cannot move throughout the structure carrying charge.
• Explain why graphite has a very high melting point?

  Each carbon atom forms 3 strong covalent bonds with other atoms. There are many strong covalent bonds in total, taking lots of energy to break
• Explain why graphite can conduct electricity?

  as each carbon only forms 3 covalent bonds, each one has a delocalised electron. These can move throughout the structure, carrying charge.
• Explain why graphene can be used as a lubricant?

  it contains layers held by weak intermolecular forces. These can slide easily over each other
• Explain why diamond is hard but graphite is soft?

  All carbon atoms in diamond are held by strong covalent bonds. All atoms are connected together, and it takes a very large force to break these bonds. Graphite contains layers held by weaker intermolecular forces. This means forces cause these layers to slide, making it soft.
• What is the difference between the structure of graphite and graphene?

  graphite contains many layers, graphene has one layer. Therefore there are no intermolecular forces in graphene.
• State the properties of graphene?

  good electricity conductor, high melting and boiling points, high tensile strength, transparent and low density
• Explain why graphene has a high tensile strength?

  it has a single layer containing many strong covalent bonds that take alot of force to break
• Why is graphene transparent, whereas graphite is a grey solid?

  Graphene is a single layer of graphite, allowing light to pass through it, while graphite is a stack of multiple layers reducing the amount of transmissed light
• What are fullerenes?

  allotropes of carbon that are hollow inside
• Name 2 fullerenes?

  Buckminsterfullerene balls, Carbon nanotube
• Describe the structure of carbon nanotubes?

  a very tiny tube made of carbon. Each carbon forms 3 covalent bonds with others
• Explain why carbon nanotubes can conduct electricity?

  As each carbon only forms 3 covalent bonds, there are delocalized electrons that can move freely throughout the structure, carrying charge
• Explain why carbon nanotubes have high tensile strengths?

  there are many strong covakent bonds between carbon atoms taking a lot of force to break
• Describe the structure of buckminsterfullerene balls?

  they are spheres made of 60 carbon atoms. They are hollow inside.
• Do buckminsterfullerene balls conduct electricity? explain your answer.

  No, even though they have delocalised electrons. only flow across the surface each ball. They cannot 'jump' to different balls so the substance cannot conduct electricity.
• What forces hold two buckmisterfullerene balls together?

  weak intermolecular forces
• Does buckmisterfullerene have high or low melting points? explain your answer

  low melting points, there are weak intermolecular forces between balls that take a small amount of energy to break
• Explain how buckminsterfullerene can be used to deliver medical drugs into patients?

  they are hollow inside, so can store drugs