Sunday, 29 September 2013

Structure and Properties of Ionic Bonding

Ionic Bonding 

  • Ionic bonding is the strong electrostatic force of attraction between oppositely charged ions. 
  • Metals lose e- (electrons) to form positive ions - cations 
  • Non-metals gain e- to form negative ions - anions 
  • e.g. Ionic bonding in sodium chloride.

Structure of Ionic Compounds

  • Ionic compounds form a giant ionic lattice held together by many strong ionic bonds.
  • Each Cl- is surrounded by 6 Na+
  • Each Na+ is surrounded by 6 Cl-

  • A similar structure is seen with MgO but this is stronger as the Mg2+ ion is bonded more strongly to O2+

Properties of Ionic Compounds

  • High MP (melting point) & BP (boiling point) - there are many strong ionic bonds to break due to strong electrostatic attraction between oppositely charged ions.
  • Crystalline - the ions are packed together regularly.
  • Brittle - the arrangement of ions allows crystals to split easily.
  • Soluble in water - Water is a polar molecule. These molecules are electrostatically attracted to the +ve (positively charged) and –ve (negatively charged) ions in the lattice, and pulls it apart.
  • If the attractions between the water molecule are stronger than the attractions between the ionic lattice, it will dissolve.