properties of materials

• A substance's physical state depends on its temperature, pressure, and volume.
• The boiling point is the temperature at which a liquid turns into a gas.
• The melting point is the temperature at which a solid turns into a liquid.
• The three states of matter are solid, liquid, and gas.
• carbon is in group 4 so its atoms have 4 electrons in their outer shell
• diamond, graphite, graphene and fullerenes are different forms of carbon
• allotropes are different forms of an element in the same state but with different atomic arrangements
• diamond exists as a giant covalent structure, covalent bonds are strong and diamond has many of them this means diamond has a very high mp and is very hard. diamond has no delocalised electrons so does not conduct electricity
• graphite exists as a giant covalent structure, in which each carbon atom is covalently bonded to 3 other carbon atoms one electron in the outer shell of each atom is not involved in bonding so becomes delocalised therefore graphite conducts electricity. graphite has a layered structure, they many strong covalent bonds in the layers that gives graphite a very high mp, however the forces between each layer are weak so layers can slide over each other easily.
• graphene is a carbon allotrope that resembles a single layer of graphite, almost completely transparent, extremely strong and conducts electricity
• diamond and graphite are two allotropes of carbon
• fullerenes form a large family of carbon allotropes
• a nanotube resembles a sheet of graphene rolled into a tube, nanotubes are strong
• when a substance melts or boils, forces of attraction between its particles overcome - some or all of them break
• some bonds break going from solid to liquid
• all bonds break going from liquid to gas
• bonds form when a substance condenses or freezes
• some bonds form going from gas to liquid
• many bonds form going from liquid to solid
• substances in solid state at room temp:

  • metals
  • ionic compounds
  • giant covalent substances
• f= forces b=bonds

  example of bonds involved in state changed

  substance bonds involved strength example

  metal metallic b strong iron

  ionic compound ionic b strong sodium chloride

  giant covalent covalent b strong diamond

  simple molecule intermolecular f weak water
• some substances can sublime - change directly from solid to gas e.g. iodine
• a nanoparticle is a particle between 1nm and 100nm across
• possible risks of nanoparticles

  • if breathed in skin can absorb them
  • they take a long time to break down
  • toxic substances may stick to their surfaces
• What is an alloy?

  A mixture of two or more chemical elements, at least one of which is a metal, in which the elements are evenly blended at the atomic or molecular level to form a new material with unique properties.
• Buckminsterfullerene


  A type of molecular carbon structure composed of 60 carbon atoms, known for its unique spherical shape and symmetrical structure.