- 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.