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
Answer:
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
Answer:
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
Answer:
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
Answer:
a. Hydrochloric acid

b. Sulphuric acid

c. Nitric acid

d. Ethanoic acid

e. Phosphoric acid

f. Carbonic acid