Polymers and giant covalent structures

• Polymers


  Long chains of repeating units
• Polymers

  • All the atoms are joined by strong covalent bonds
  • To find the molecular formula, write the molecular formula of the repeating unit in brackets and put an n outside
  • The intermolecular forces between polymer molecules are larger than between simple covalent molecules, so more energy is needed to break them
  • Most polymers are solid at room temperature
  • The intermolecular forces are still weaker than ionic or covalent bonds, so they generally have lower boiling points than ionic or giant molecular compounds
• Giant covalent structures

  Macromolecules where all the atoms are bonded to each other by strong covalent bonds
• Giant covalent structures

  • They have very high melting and boiling points as lots of energy is needed to break the covalent bonds between the atoms
  • They don't contain charged particles, so they don't conduct electricity (except for a few weird exceptions such as graphite)
  • The main examples are diamond, graphite, and silicon dioxide (silica)
• Giant covalent structures

  • Diamond
  • Graphite
  • Silicon dioxide (silica)
• Each carbon atom in diamond forms four covalent bonds in a very rigid giant covalent structure
• In graphite, each carbon atom forms three covalent bonds to create layers of hexagons, and each carbon atom also has one delocalised (free) electron
• Silicon dioxide (silica) is what sand is made of, and each grain of sand is one giant covalent structure of silicon and oxygen