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Ionic Properties

Giant Ionic Lattice

  • Ionic compounds found in giant ionic lattices
  • Giant 3D structures made of millions of alternating ions
  • Positive cations will be found to negative anions in opposite and alternating 3D pattern
  • Ions are held together by:
    • Strong ionic bonds
      • Happens due to electrostatic forces of attraction between cations and anions

Properties of Ionic Substances

High melting and boiling points

  • Ionic bonds are attracted with strong forces of electrostatic attraction between cations and anions
  • In order to melt the substance, a high amount of energy must be applied to break the bonds

Brittle

  • When a force is applied, the ions shift
  • When the ions shift, they will be rearranged where it is not alternating
  • The same type of ion will repel each other and break

Insulator as Solids

  • In a solid, the ions are held in a lattice therefore they cannot move
  • All electrons involved in bonding

Conductor as Liquids

  • When molten/dissolved, the ions are no longer in the lattice and are free to move
  • Ions can carry a charge now

Crystalline

  • Alternative cations and anions are arranged in an orderly way in a giant ionic lattice
  • As this is so regular on a microscopic scale, it will be the same on a macroscopic scale

Practical to find out Ionic Substances

Health and safety

  • Eye protection to be used
  • Toxic fumes may be produced so do not keep the circuit connected for too long
  • Toxic gases may be produced, once observations have been made, swwitch off the circuit

Method

  • Set up the equipment as shown in the diagram

Beaker Electrode

  • Choose a test substance and add some to boiling tube
  • Add water to the boiling tube to about half full
  • Seal the boiling tube using a bung
  • Hold your thumb over the bung and shake the boiling tube
  • Observe and record if the substance dissolves
    • If the substance dissolves add to beaker
    • Observe and record whether the lamps light or not.
      • If both tests suceed, the substance is ionic
    • After recording results, empty the beaker and clean apparatus of impurites
  • Repeat the steps with remaining substances