Chemical Bonding

• Covalent bonds


  Atoms share electrons so all atoms have full outer shells
• Simple molecular substances


  • Chlorine
  • Ammonia
• Simple molecular substances


  • Small molecules made up of a few conveniently bonded atoms
  • Separate molecules joined by weak intermolecular forces
• Giant covalent structures


  • Diamond
  • Graphite
  • Silicon dioxide
• Giant covalent structures


  • Made of large numbers of non-metal atoms bonded by covalent bonds
  • Atoms arranged in regular repeating lattices
  • Very strong
  • High melting and boiling points
• Covalent bonds are strong, requiring a lot of energy to break
• Simple molecular substances


  Melt/boil by breaking weak intermolecular forces, not covalent bonds
• Simple molecular substances only require low temperatures to melt/boil
• Larger molecules in halogens (Cl, Br, I)

  More intermolecular forces, higher melting/boiling points
• Simple molecular substances don't conduct electricity as they have no free electrons or charged particles
• Silicon dioxide (silica) is made of silicon and oxygen atoms in a 1:2 ratio, and is the main component of sand
• Giant covalent structures generally don't conduct electricity as they lack free charged particles
• Graphite is an exception as a conductive giant covalent structure