Sodium chloride is made from two ki

Sodium chloride is made from two kinds of ions. They are:
- Sodium ions, which have a positive charge (+),and
- Chloride ions, which have a negative charge (-).
Sodium chloride is a solid. Figure 5.14 show a model of solid sodium chloride. The solid consists of many layers of sodium ions and chloride ions. Notice that the number of sodium ions is equal to the number of chloride ions. Therefore, we write the formula of sodium chloride as NeCl.
Compounds made up of ions are called ionic compounds. Calcium carbonate, magnesium oxide and copper (II) sulfate are three other examples of ionic compounds.

Names and Formulae of Compounds
Table 5.1 gives the names and formulae of some compounds and the elements present in these compounds.