bonding

• properties of graphite:

  • delocalised electron per atom so can conduct electricity and heat
  • each carbon has 3 bonds, hexagonally bonded
  • weak intermolecular forces between layers but no covalent bonds it is soft and slippery
  • many strong covalent bonds which require lots of energy to overcome so has high melting and boiling points
• properties of diamond:

  • each carbon has 4 bonds so no delocalised electrons so does not conduct electricity
  • many covalent bonds which take a lot of energy to overcome so have a high melting and boiling point
  • very hard
• uses of carbon fullerenes:

  • lubricants
  • to deliver drugs to parts of the body
  • catalysts
  • reinforcing materials like tennis rackets (nanotubes)
  • nanotechnology
• Properties of ionic compounds:

  • giant ionic lattices have strong electrostatic forces of attraction in all directions between oppositely charged electrons
  • high melting and boiling points
  • conduct electricity when melted or dissolved in water
• Why do ionic compounds only conduct electricity dissolved in water or melted?

  The ions become free to move and carry current throughout the layers of the compound.
• properties of small molecules:

  • gases or liquids with low melting and boiling points
  • weak intermolecular forces which are broken during melting
  • dont conduct electricity as they don’t have an overall charge
• properties of metals:

  • giant structures of atoms with strong metallic bonding
  • most have high melting and boiling points
  • layers of atoms are able to slide over eachother so are malleable
• properties of alloys:

  • made from 2 or more different types of metals
  • different sized atoms distort layers making it harder for them to slide over each other
  • harder than pure metals
• chemical bonds:

  1. ionic
  2. covalent
  3. metallic
• metallic bonding consists of positive ions and delocalised electrons arranged in a regular pattern.
• in metallic bonding, delocalised electrons consist of the electrons lost from the now positive ions.
• polymers are large covalent bonded chains
• nano particles are 1nm-100nm in size
• nanoparticles have a high surface area to volume ratio and therefore make good catalysts
• nanoparticles can be used in suncream and deodorants without leaving white marks
• nano particles have different properties to the bulk chemical due to high surface area to volume ratio
• nanoparticles allow smaller quantities of a material to be more effective than materials with larger particle sizes