covalent bonding

• bonds in molecules


  • form when 2+ atoms bond together (doesn't matter if they're the same or different atoms)
  • held together by covalent bonds
  • single covalent bonding contains shared pair of electrons
  • two atoms share electrons so they've both got full outer shells
  • both positive nuclei are electrostatically attracted to the shared electrons
  • can form double or triple covalent bond
• giant covalent structures


  • have huge network of covalently bonded atoms
  • sometimes called macromolecular structures
  • carbon atoms form this type of structure because they each form four sarong covalent bonds (e.g. graphite and diamond)
• graphite


  • hexagon sheets w delocalised electrons
  • used as dry lubricants + in pencils because they're slippery - weak bonds between sheets so they can slide over each other
  • electrical conductor bc delocalised electrons aren't attached to a C atom so are free to move along the sheets and carry a charge
  • used to make strong, lightweight sports equipment bc low density - layers are quite far apart compared to the lengths of the covalent bonds
  • very high melting point because of the strong covalent bonds in the hexagon sheets
  • insoluble w any solvent bc covalent bonds too strong to break
• diamond

  • each carbon atom covalently bonded to 4 other carbon atoms
  • v high melting point
  • extremely hard - used in diamond-tipped drills and saws
  • good thermal conductor bc vibrations easily travel through stiff lattice
  • can't conduct electricity bc outer electrons held in localised bonds
  • won't dissolve in any solvent
  • can be cut to form gemstones which's structure refracts light a lot so it sparkles
• dative covalent bonding


  • both electrons come from one atom
  • e.g. ammonium ion - nitrogen atom donates pair of electrons to a proton (H+)