Classifying Oxides (Cambridge (CIE) IGCSE Combined Science): Revision Note

Classifying oxides as acidic or basic

What are oxides?

• Oxides are compounds made from one or more atoms of oxygen combined with one other element

• Examples of oxides include:

  • Magnesium oxide - MgO

  • Zinc oxide - ZnO

  • Potassium oxide - K₂O

  • Carbon dioxide - CO₂

  • Sulfur dioxide - SO₂

  • Water - H₂O

• Oxides can be classified based on their acid-base characteristics

Acidic oxides

• Acidic oxides are formed when a non-metal element combines with oxygen

• Common examples include:

  • CO₂

  • SO₂

  • NO₂

  • SiO₂

Basic oxides

• Basic oxides are formed when a metal element combines with oxygen

• Common examples include:

  • CuO

  • CaO

Basic and acidic oxides 

Metals form basic oxides while non-metals form acidic oxides