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• Chemical bonds

  Three types of strong chemical bonds: Ionic, covalent and metallic
• Ionic bonding

  • Occurs in compounds formed from metals combined with nonmetals
  • The particles are oppositely charged ions
• Covalent bonding

  • Occurs in nonmetallic elements and in compounds of nonmetals
  • The particles are atoms which share pairs of electrons
• Metallic bonding

  • Occurs in metallic elements (and alloys)
  • The particles are atoms which share delocalised electrons
• Ions

  Charged particles
• Metal atoms

  Lose electrons to make positive ions
• Nonmetal atoms

  Gain electrons to make negative ions
• When a metal atom reacts with a nonmetal atom

  Electrons in the outer shell of the metal atom are transferred
• The ions produced by metals in Group 1 and Group 2, and by nonmetals in Groups 6 and Group 7, have the electronic structure of Group 0 (noble gas)
• Electron transfer during ionic compound formation

  • Sodium Chloride
• The electron transfer during the formation of an ionic compound can be represented by a dot and cross diagram
• Ionic compound

  A giant structure of ions held together by strong electrostatic forces of attraction between oppositely charged ions
• Ionic compounds

  • Have high melting and boiling points due to the strong bonds between ions
  • When solid, they can't conduct electricity because ions are fixed in place
  • When molten, the ions are free to move and will carry an electrical charge
• Covalent bonding

  Atoms share pairs of electrons to form strong covalent bonds
• Covalently bonded structures

  • May consist of small molecules
  • Some have very large molecules e.g. polymers
  • Some are giant covalent structures e.g. diamond, silicon dioxide
• Covalently bonded molecules

  • Ammonia (NH3)
  • Polyethene
• Simple covalent bonds

  • Have low boiling points because there are weak intermolecular forces of attraction between the molecules that require little energy to overcome
  • Do not conduct electricity as they do not contain ions or delocalised electrons that are free to move and carry a charge
• Diamond and Graphite


  • Have high melting points because of the strong covalent bonds between carbon atoms
  • Diamond is very hard because of the strong 3D network of covalent bonds
  • Graphite can conduct electricity because each carbon atom forms 3 covalent bonds, leaving delocalised electrons that can carry a charge
  • Graphite is soft and slippery because it has layers that can slide over each other due to weak intermolecular forces between the layers
• Nanotubes/fullerenes

  Cylindrical/spherical forms of carbon useful for electronics and nanotechnology
• Polymers

  Very large molecules linked by covalent bonds, with strong intermolecular forces
• Graphene

  A single layer of graphite, useful in electronics
• Metal bonding

  Giant structures of metal atoms with delocalised electrons that are free to move through the whole structure, giving rise to strong metallic bonds
• Metals

  • Have strong electrostatic attraction between positive metal ions and shared negative delocalised electrons
  • Are good conductors of electricity and heat
  • Are malleable as metal atoms can slide over each other
• Alloys

  • Are harder than pure metals because the different sized atoms distort the layers
• States of matter

  • Solid, liquid, gas
  • Melting and freezing occur at melting point
  • Boiling and condensing occur at boiling point
• The amount of energy needed to change state depends on the strength of the forces between the particles of the substance</b>
• Stronger the forces between particles, the higher the melting and boiling points of the substance
• Particle Theory doesn't show forces