The structure and properties of ionic compounds

• The ions in ionic compounds are held together because of the strong electrostatic attraction between the oppositely charged ions
• The electrostatic forces around each ion extend in all directions so each ion attracts several oppositely charged ions around it. This results in a giant lattice where the ions are regularly arranged in a repeating pattern
• Even though there are many ions in a giant ionic lattice, the numbers of each ion are in the same ratio as they are in the formula of the compound. For example, in NaCl the number of sodium and chloride ions are equal in number. In CaBr², there are twice as many bromide ions as there are calcium ions
• Ionic compounds have high melting and boiling points because the ionic bonds are strong and in the giant lattice there are lots of them to break. You need a lot of energy to break these bonds
• Ions are charged particles and when they move they can carry an electric current
• In solid form ionic compounds do not conduct electricity because the ions are fixed in a lattice and do not move and therefore they cannot carry the current
• If an ionic compound is dissolved in water or is in molten form, then the ions are no longer fixed in a lattice and can move. This means that the ionic compounds will conduct electricity