covalent bonding

    Cards (10)

    • A covalent bond is the electrostatic attraction between two nuclei and a shared pair of electrons.
    • covalent bonding forms molecules
    • simple molecular structure and boiling point
      contains many individual covalently bonded molecules held together by weak intermolecular forces of attraction
      low boiling point as the weak intermolecular forces need to be broken
      as the mass of the structure increases (mr increases) the intermolecular forces get stronger and boiling point gets higher
    • giant covalent structureand boiling point
      many atoms all covalently bonded together
      eg. diamond, graphite, silicon dioxide
      very high boiling points as you need to separate the strong covalent bonds
      no ions or delocalized electrons so poor conductors
      apart from graphite
    • graphite
      layers of giant covalent structures (hexagonal lattice structures of carbon) (called graphenes) with weak forces of attraction holding them together so they can slide over eachother - making it soft and why it is used as a lubricant
      layers have delocalised electrons between them which are free to move so can conduct electricity
      high melting point because of strong covalent bonds
    • do covalent structures conduct electricity

      covalent structures generally don't conduct electricity as they lack ions or delocalized electrons
    • how are covalent bonds formed
      Covalent bonds are formed when two non-metal atoms share pairs of electrons to achieve a full outer shell.
    • diamond
      tetrahedral lattice of carbon atoms
      giant covalent structure
      high melting point as many (because of tetrahedral shape) strong (covalent) bonds need to be broken.
      hard as lots of energy required to scratch and break strong covalent bonds
    • c60 (buckminster) fullerene
      Its molecules are made up of 60 carbon atoms joined together by strong covalent bonds in a hollow sphere.
      There are weak intermolecular forces between molecules of buckminsterfullerene, so is slippery and has a low melting point.
      can't conduct electricity as delocalized electrons can't move across molecules
    • allotrope
      different form of same element
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