chemistry paper 1

• Giant covalent structures are made up of thousands of atoms held together by strong covalent bonds
• Diamond


  • Every carbon atom makes four strong covalent bonds
  • Incredibly hard
  • Does not conduct electricity
• Graphite


  • Every carbon atom makes three bonds, leaving one electron delocalized
  • Sheets held together by weak intermolecular forces, can slide over each other
  • Soft and slippery, useful as a lubricant
• Graphene


  • Single layer of graphite, can conduct electricity
• Fullerenes


  • Nanoparticles made of carbon atoms, form tubes and balls
• Silicon dioxide


  • Every silicon atom joined to four oxygen atoms by strong covalent bonds
  • High melting point, does not conduct electricity
• Relative atomic mass


  Mass of an element compared to 1/12 the mass of carbon-12
• Relative formula mass (Mr)


  Sum of the relative atomic masses of the atoms in a compound