Properties of Ionic Compounds (Oxford AQA IGCSE Chemistry)

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 O^2- so will have a higher melting point than sodium chloride which contains the ions, Na⁺ and Cl^-

For electrical current to flow there must be freely moving charged particles such as electrons or ions present 

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