Giant covalent molecules

• In a giant covalent structure:

  • the atoms are joined to each other by strong covalent bonds
  • Regular arrangements of atom
  • High melting and boiling points as large amounts of energy are required needed to over come strong covalent bonds
  • Most giant covalent substances cannot conduct electricity because they have no charged particles that are free to move
• Diamond

  • The atoms from 4 covalent bonds with atoms
  • There is tetrahedral arrangement of electrons
  • There are no free atoms
  • Diamonds have high melting and boiling points because large amounts of energy are required to break its bonds
  • Diamonds do not conduct electricity
• Graphite

  • The atoms from three covalent bonds with other atoms to form layers
  • Atoms are arranged in a pattern of hexagons
  • There are free electrons
  • Graphite has high melting and boiling points because large amounts of energy is required to break covalent bonds
  • Graphite conduct electricity because its electrons are able to move between layers
  • Graphite is lubricant as its layers slide over one another
• Graphene and fullerenes

  • Graphene is a single layer of graphite
  • Has high melting and boiling points
  • Is very strong
  • Graphene conducts electricity as it contains delocalised electrons
• Nanotubes

  • Molecules of carbon atoms with hollow shapes
  • Nanotubes are cylindrical
  • Nanotubes have high tensile strength and conduct electricity
• Polymers

  • Have very large molecules
  • The atoms in a polymer molecule are joined together in chains
  • There are Variable number of atoms in the chains of a given polymer
  • Intermolecular forces between polymer molecules are stronger than the intermolecular forces between smaller molecules
  • So polymer melt at a higher temperatures than substances with smaller molecules