Covalent Bonding

• How are covalent bonds formed?

  By atoms sharing electrons.
• Which type of atoms form covalent bonds between them?

  Non-metals.
• Describe the structure and bonding of a giant covalent substance.

  Billions of atoms bonded together by strong covalent bonds.
• Describe the structure and bonding of small molecules.

  Small numbers of atoms group together into molecules with strong covalent bonds between the atoms and weak intermolecular forces between the chains.
• Why do giant covalent substances have high melting points?

  It takes a lot of energy to break the strong covalent bonds between the atoms.
• Describe the structure and bonding of polymers.


  Many identical molecules joined together by strong covalent bonds in a long chain, with weak intermolecular forces between the chains.
• What do small molecules have low melting points?

  Only a small amount of energy is needed to break the weak intermolecular forces.
• Why do large molecules have higher melting and boiling points than small molecules?

  The intermolecular forces are stronger in large molecules.
• Why do most covalent substances not conduct electricity?

  Do not have delocalised electrons or ions.
• Describe the structure and bonding in graphite.

  Each carbon atom is bonded to three others in hexagonal rings arranged in layers - it has delocalised electrons and weak forces between the layers.
• Why can graphite conduct electricity?

  The delocalised electrons can move through the graphite.
• Explain why graphite is soft.

  Layers are not bonded so can slide over eachother.
• What is graphene?


  One layer of graphite.
• Give two properties of graphene.

  Strong and conducts electricity.
• What is a fullerene?

  Hollow cage of carbon atoms arranged as a sphere or a tube.
• What is a nanotube?


  Hollow cylinder of carbon atoms.
• Give two properties of nanotubes.

  High tensile strength, conduct electricity.
• Give three uses of fullerenes.

  Lubricants, drug delivery (spheres) and high-tech electronics.