polymers and giant covalent Structures

• Polymers:

  • Long chains of molecules
  • joined by Strong covalent bonds
  • The sections are repeating, so to draw a polymer you Just draw the repeated section, the repeating unit
  • Molecular formula is just the pattern in brackets with an N outside of it
• Polymers properties:

  • Intermolecular forces between polymer molecules are larger than Simple covalent so require more energy to break them
  • so polymers are Solid at room temp
  • Intermolecular forces are still weaker than other bonds so they generaly have lower boiling points than ionic or giant molecular compounds
• Giant covalent Structures:

  • Bonded to eachother by Strong covalent bonds
  • very high melting and boiling points
• Diamonds:

  • Made up of carbon atoms that each form four covalent bonds, making it extremely hard
  • Doesn't conduct electricity as it has no free electrons or ions
• Graphite:

  • each carbon atom forms three covalent bonds, creating sheets of carbon atoms arranged in hexagons
  • There aren't any covalent bonds between the layers so they are free to move over eachother, making graphite Soft and slippery.
  • Its got a high melting point
  • only 3/4 of carbon's electrons are used in bonds so each carbon atom has one delocalised electron meaning it conducts electricity and thermal energy
• Graphene

  • sheet of carbon atoms joined together in hexagons
  • Only one atom thick making it two-dimensional
  • the network of covalent bonds makes it very strong and light, so it can be added to lots of materials to improve their strength
  • contains delocalised electrons so can conduct electricity
• Fullerenes:

  1. molecules Of carbon shaped like closed tubes or hollow balls
  2. Mainly arranged in hexagons but could be in pentagons or heptagons
  3. Fullerenes can 'cage' other molecules. It can form around another atom or molecule, trapping it inside. This can be used to deliver drugs into the body
  4. huge surface area, so make good Catalysts and lubricants
• Nanotubes:

  • tiny carbon cylinders
  • can conduct heat and electricity
  • High tensile Strength (don't break when stretched )
  • Can be used in electronics or to Strengthen materials without adding weight, like tennis rackets