SPM Chemistry

Formula of Ionic Compounds

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Chemical Formlula 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