• Positive ions (cations) form by metals losing valence electrons.

• Negative ions (anions) form by non-metals gaining electrons.

• The number of electrons lost or gained is determined by the electron configuration of the atom.

• The ionic bond is due to electrostatic attraction between oppositely charged ions.

• Under normal conditions, ionic compounds are usually solids with lattice structures.

• Deduction of the formula and name of an ionic compound from its component ions, including polyatomic ions.

• Explanation of the physical properties of ionic compounds (volatility, electrical conductivity and solubility) in terms of their structure.

• Students should be familiar with the names of these polyatomic ions: NH4+, OH-, NO3-, HCO3-, CO32-, SO42- and PO43-.