C2 - Bonding, Structure, and Properties of Matter

• The Particle Model


  • Can be used to explain how the particles are arranged and how they move in solids, liquids and gases
• Particles in solids


  1. Have a regular arrangement

  2. Are very close together

  3. Vibrate about fixed positions
• Particles in liquids


  1. Have a random arrangement

  2. Are close together

  3. Flow around each other
• Particles in gases


  1. Have a random arrangement

  2. Are much further apart

  3. Move very quickly in all directions
• Melting point


  The temperature at which a pure substance melts
• Boiling point


  The temperature at which a pure substance boils
• The amount of energy required for a substance to change state


  Depends on the amount of energy required to overcome the forces of attraction between the particles
• The stronger the forces of attraction


  The greater the amount of energy needed to overcome them, the higher the melting point and boiling point will be
• Substances with high melting points due to strong bonds


  • Ionic compounds
  • Metals
  • Giant covalent structures
• Ionic bonding


  Involves a transfer of electrons from metal atoms to non-metal atoms, forming positive and negative ions that are attracted to each other
• Ionic bonds


  • Are strong electrostatic forces of attraction between positive metal ions and negative non-metal ions
• Metallic bonding


  Occurs in metallic elements and alloys, where electrons in the outer shell are delocalised and not bound to one atom
• Metallic structure

  • Has a regular arrangement (lattice) of positive ions held together by electrostatic attraction to the delocalised negatively charged electrons
• Metallic bond


  The attraction between the positive metal ions and the delocalised negatively charged electrons
• Properties of metals


  • Metallic bonds are very strong, so most metals have high melting and boiling points

  Delocalised electrons can move around freely and transfer energy, making metals good thermal and electrical conductors

  Particles have a regular arrangement, allowing the layers to slide over each other easily, making metals ductile and malleable
• Metal uses and properties

  • Aluminium: High-voltage power cables, furniture, drinks cans, foil - Corrosion resistant, ductile, malleable, good conductivity, low density

  Copper: Electrical wiring, water pipes, saucepans - Ductile, malleable, good conductivity

  Gold: Jewellery, electrical junctions - Ductile, shiny, good conductivity
• Covalent bond


  A shared pair of electrons between atoms
• Covalent bonding occurs in


  • Non-metallic elements (e.g. oxygen, O2)

  Compounds of non-metals (e.g. sulfur dioxide, SO2)
• Giant covalent structures

  • Have very high melting and boiling points due to strong covalent bonds

  Diamond: Giant, rigid covalent structure with each carbon atom forming 4 strong covalent bonds, making it very hard but not electrically conductive

  Graphite: Layered, hexagonal structure with weak intermolecular forces between layers, allowing the layers to slide, making it soft and slippery, but with delocalised electrons allowing it to conduct heat and electricity
• Graphene


  A form of carbon, a single layer of graphite, just one atom thick
• Graphene

  • Very strong
  • Good thermal and electrical conductor
  • Nearly transparent
• Fullerenes


  Molecules of carbon with hollow shapes, including tubes, balls and cages
• Fullerenes


  • Structure based on hexagonal rings of carbon atoms
  • Sometimes contain five or seven carbon atoms
• Fullerenes


  • Buckminsterfullerene (C60)
• Carbon nanotubes


  Cylindrical fullerenes with very high length to diameter ratios
• Carbon nanotubes


  • Properties make them very useful in nanotechnology, electronics and materials
• Matter


  The material that everything is made up of
• Particle


  A small piece of matter
• Melting point


  The specific temperature at which a pure substance changes state, from solid to liquid and from liquid to solid
• Boiling point


  The specific temperature at which a pure substance changes state from liquid to gas and from gas to liquid
• Aqueous


  Dissolved in water
• Ionic bond


  The force of attraction between positive and negative ions
• Ion


  An atom that has gained or lost electrons and now has an overall charge
• Electrostatic


  A force of attraction between oppositely charged species
• Molten


  Liquefied by heat
• Covalent bond


  A shared pair of electrons between atoms in a molecule
• Intermolecular


  Between molecules
• Diamond


  A form of carbon, with a giant covalent structure, that is very hard
• Graphite


  A form of carbon, with a giant covalent structure, that conducts electricity
• Delocalised

  Not bound to one atom