AP Chemistry Unit 2.3 Structure of Ionic Solids

Ionic Solids

  • Ionic solids: stable substances held together by opposite charges (electrostatic attraction)
  • Will not conduct electricity in solid form → only when ions are mobile (melted (molten) or dissolved)
    • In order to conduct electricity need charged particles that must be free to flow
  • Ions pack themselves to maximize attractions between opposite charges and to minimize repulsion between like ions → like charges will be far away from each other → cations and anions should alternate within a row and column to avoid them repelling each other
  • As the size of ions decrease and charges increase, lattice energy increases → compound more stable and MP higher
  • Why are ionic solids hard and brittle?
    • Hard: the cations and anions are locked tightly into place because of the very strong electrostatic attraction (ionic bonds)
    • Brittle: ionic bonds as result of electrostatic attraction create crystals in rigid, lattice structures that, when pressured, causes one layer to slide past another and break
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