C2.3

• What group is carbon in on the periodic table?

  Group 4
• How many electrons are in the outer shell of a carbon atom?

  Four electrons
• What type of bonds can carbon form?

  Four covalent bonds
• What structures can carbon atoms form with each other?

  Chains and rings
• With which elements can carbon form covalent bonds?

  Hydrogen and oxygen
• What are the allotropes of carbon?

  • Graphite
  • Diamond
  • Fullerenes
• What is the main difference between diamond and graphite?

  Diamond is transparent and very hard, while graphite is grey-black and soft
• Why do diamond and graphite have different properties?

  The differences are due to their structure and bonding
• What type of structure does diamond have?

  A giant covalent structure
• How many carbon atoms is each carbon atom in diamond covalently bonded to?

  Four other carbon atoms
• Why does diamond not conduct electricity?

  It has no delocalised electrons
• What is the melting point of diamond?

  High melting point, lots of energy needed
• Why is diamond suitable for the tips of dental drills?


  Because it is hard
• What is the appearance of diamond?

  Colourless and shiny
• How does graphite's structure differ from diamond's structure?

  Each carbon atom in graphite is covalently bonded to just three other carbon atoms
• What happens to the fourth electron in graphite's outer shell?

  It becomes delocalised
• Why does graphite conduct electricity?

  Because the delocalised electrons are free to move through the structure
• What is the structure of graphite?

  A layered structure with interlocking hexagons
• What gives graphite a very high melting point?


  The many strong covalent bonds in the layers
• Why can layers in graphite slide over each other easily?

  Because the forces between each layer are weak
• What is the physical property of graphite that makes it useful as a lubricant?

  It is slippery
• Is graphite soluble in water?

  No, it is insoluble in water
• What is graphene?


  A carbon allotrope that resembles a single layer of graphite
• What are the properties of graphene?

  Almost transparent, extremely strong, and conducts electricity
• What are fullerenes?


  A large family of carbon allotropes shaped like tubes or balls
• What is a nanotube?


  A nanotube resembles a sheet of graphene rolled into a tube
• What are the properties of nanotubes?


  They are strong and used to reinforce some sports equipment
• What is a buckyball?

  A buckyball resembles a sheet of graphene closed to make a hollow ball
• What potential uses do buckyballs have?

  As lubricants and for delivering medical drugs directly to cells
• What happens when a substance melts or boils?


  Forces of attraction between its particles are overcome
• What types of bonds can break when a substance changes state?

  Metallic bonds, ionic bonds, covalent bonds, or intermolecular forces
• What determines the melting and boiling points of substances?

  The strength and number of bonds that must be broken
• What is the relationship between strong bonds and melting/boiling points?

  Substances with many strong bonds have high melting and boiling points
• What happens when a substance condenses or freezes?

  Stored chemical energy is transferred to the surroundings
• What state are simple molecules usually in at room temperature?

  Liquid or gas
• What types of substances are usually solid at room temperature?

  Metals, ionic compounds, and giant covalent substances
• What is a brittle substance?


  A substance that cracks or breaks when an external force is applied
• What is a malleable substance?


  A substance that can change shape without cracking or breaking
• Why are metals considered malleable?

  Because layers of metal ions can slide over one another without breaking bonds
• What holds metal ions in a lattice structure?


  Forces that attract them to a 'sea of delocalised electrons'