chem - covalent and ionic compounds

• Ionic compounds

  • Have high melting and boiling points
• Oppositely charged ions in the lattice structure

  Are attracted to each other by strong electrostatic forces which hold them firmly in place
• Large amounts of energy


  Are needed to overcome ionic electrostatic forces as the m.p. and b.p. are high
• Ionic substances can conduct electricity

  When in either the molten state or when dissolved in solution. In both cases the ions must be able to move and carry the charge
• Solid ionic substances

  The ions are in fixed positions and cannot move, hence they do not conduct electricity
• Simple covalent substances

  • Have very strong covalent bonds between the atoms in each molecule, but much weaker intermolecular forces between individual molecules
• When one of these substances melts or boils

  It is these weak intermolecular forces that break, not the strong covalent bonds
• covalent - less energy is needed to break the molecules apart, so they have lower m.p. and b.p. than ionic compounds
• Covalent compounds

  Are poor conductors of electricity as there are no free ions or electrons to move and carry charge
• most covalent compounds do not conduct at all in the solid state and so become insulators
• Common insulators

  • Plastic coating around electrical wiring
  • Rubber
  • Wood
• Giant ionic and covalent structures

  Form huge continuous networks of atoms that are bonded together and which cannot be separated into individual units without breaking bonds