# Chemical Formula of Ionic Compounds

2 Requirements to form the formula of an ionic compound
1. Have at least 2 types of ions that contain opposite charge.
2. The amount of positive charge/charges must be equal to the amount of negative charge/charges in the compound.

Example 1 – If the Charge of the Positive Ions = Charge of Negative Ions
Write the formula of each of the following compound
1. Potassium bromide
2. Sodium chloride
a. Potassium bromide

b. Sodium chloride

Example 2 – If the Charge of the Positive Ions ≠ Charge of Negative Ions
Write the formula of each of the following compound
1. Calcium iodide
2. Sodium oxide
a. Calcium iodide

b. Sodium oxide

Example 3 – If there is more than 1 element in the ion
Write the formula of each of the compound
1. Ammonium sulphate
2. Zinc nitrate
a. Ammonium sulphate

b. Zinc nitrate

Example 4 – Formulae of Acid
Write the formula of the following acid
1. Hydrochloric acid
2. Sulphuric acid
3. Nitric acid
4. Ethanoic acid
5. Phosphoric acid
6. Carbonic acid