Properties of ionic compounds

• • Ionic compounds are made of charged particles called ions which form a giant lattice structure 
• • Ionic compounds have high melting and boiling points because:
  • They have giant structures
  • There are strong electrostatic forces of attraction between oppositely charged ions in all directions
  • The forces need lots of energy to overcome them 
• • The greater the charge on the ions, the stronger the electrostatic forces and the higher the melting point will be
  • For example, magnesium oxide consists of Mg2+ and O2- so will have a higher melting point than sodium chloride which contains the ions, Na+ and Cl-
• • Ionic compounds are poor conductors in the solid state
  • The ions are in fixed positions in the lattice
  • They are therefore unable to move and carry a charge 
• • Ionic compounds are good conductors of electricity in the molten state or in solution 
  • When the ionic compound is melted or dissolved in water, the ions are able to move and carry a charge