C2: Structure and Properties

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  • Created by: foxes
  • Created on: 14-03-16 17:17
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  • C2: Structure and Properties
    • Ionic compounds have high melting and boiling points - solids at room temperature.
      • Conduct electricity when melted or dissolved in water - ions can then move freely and can carry electrical charge through the liquid.
    • Substances made up of simple molecules - low melting and boiling points.
      • No overall charge, cannot carry electrical charge, do not conduct electricity.
    • Covalently bonded substances with giant structures have very high melting points.
    • Alloy - mixture of metals, harder than pure metals because the layers in the structure are distorted.
    • Thermosoftening polymers - soften or melt easily when heated. Forces between the polymer chains are weak - when heated the weak intermolecular forces are broken, making the polymer soft.
      • Thermosetting polymers - do not soften or melt when heated.
        • For example: electrical sockets are made of thermosetting plastics.
    • Nanoscience = the study of very tiny particles or structures between 1 and 100 nanometres in size.
      • Their very small sizes give them large surface areas and new properties that make them useful materials.
  • Ionic compounds cannot conduct electricity when solid  - ions only vibrate about fixed positions.
  • Atoms in a molecule are held together by strong covalent bonds.
  • The forces of attraction between molecules(intermolecular forces) are weak.
    • Forces are overcome when a molecular substance melts or boils.
  • Diamond and graphite - forms of carbon with very high melting points.
    • Graphite: carbon atoms form layers that can slide over each other (due to weak intermolecular forces) - conducts electricity because of delocalised electrons in its structure. Slippery and grey.
      • Diamond: carbon atoms each form four covalent bonds - exists as fullerenes. Hard and transparent.
  • Atoms join together in giant covalent structures (macromolecules).
  • Shape memory alloy = mixture of metals which respond to changes in temperature.
    • If deformed, it can return to its original shape by heating.
    • Can be bent or deformed into a different shape,
    • Can be used as dental braces.
  • Developments in nanoscience - need more research into possible issues which might arise from increased use.
    • For example: if nanoparticles are used more often -  greater risk of them getting into the air and our bodies (could affect our health and the environment).
  • Nanocages can carry drugs inside them.


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