Who this is for: Cambridge IGCSE Chemistry (0620) students who want oxides — acidic, basic, amphoteric and neutral — to become reliable marks instead of labels they apply without knowing the underlying reactions.
What query it owns: how to understand and revise oxides in Cambridge IGCSE Chemistry.
Why this is safe: this page owns the oxides revision-guide angle, while Tutopiya’s Oxides subtopic page owns the learning resource and the free Oxides quiz owns the practice.

Oxides are tested regularly in the Acids, Bases and Salts unit of Cambridge IGCSE Chemistry (0620). Examiners expect you to classify oxides as acidic, basic, amphoteric or neutral, predict their reactions with acids and bases, and link oxide type to the metal or non-metal they contain. This guide covers the syllabus definitions, the classification rules, and the question types that appear every year.

Key takeaways

• Acidic oxides (usually non-metal oxides) react with bases/alkalis to form salts.
• Basic oxides (usually metal oxides) react with acids to form salts and water.
• Amphoteric oxides react with both acids and bases — e.g. aluminium oxide, zinc oxide.
• Neutral oxides (e.g. water, carbon monoxide) do not react with acids or bases.

What are oxides in Cambridge IGCSE Chemistry?

An oxide is a compound containing oxygen combined with another element. At IGCSE level oxides are classified by their reaction behaviour: acidic oxides form acids when dissolved in water and react with bases; basic oxides react with acids; amphoteric oxides react with both; neutral oxides show neither behaviour. This classification links directly to the periodic table — non-metal oxides tend to be acidic and metal oxides tend to be basic, with notable exceptions.

You can read the full explanation, worked examples and notes on Tutopiya’s Oxides subtopic page before you attempt questions.

The core ideas you must master

Idea	What it means	How the exam uses it
Acidic oxide	Reacts with base; often non-metal	”Classify SO₂ as acidic, basic or amphoteric.”
Basic oxide	Reacts with acid	”Write the equation for CuO + H₂SO₄.”
Amphoteric oxide	Reacts with acid and base	”State why Al₂O₃ is amphoteric.”
Neutral oxide	No reaction with acid or base	”Give an example of a neutral oxide.”
Periodic link	Metal → basic; non-metal → acidic	”Predict the oxide type of a Group 14 element.”

Classifying common oxides — the reference table

Oxide	Type	Reaction pattern
CO₂, SO₂, SO₃, NO₂	Acidic	React with alkalis → salt (+ water)
CuO, CaO, MgO, Na₂O	Basic	React with acids → salt + water
Al₂O₃, ZnO, PbO	Amphoteric	React with acids AND bases
H₂O, CO, N₂O	Neutral	No reaction with acids or bases

How to classify an oxide — step by step

1. Identify the element combined with oxygen — metal or non-metal?
2. Non-metal oxide → usually acidic (CO, H₂O are exceptions).
3. Metal oxide → usually basic (Al, Zn, Pb oxides are amphoteric).
4. Check the syllabus list of amphoteric oxides: Al₂O₃, ZnO (and PbO at IGCSE).
5. Test your classification — does it react with acid, base, or both?

Once you have worked through a few, test yourself with the free Oxides quiz — it tells you fast whether the classification rules have actually stuck.

Oxides in past-paper wording: command words that matter

Command word / phrase	What the question wants	Typical oxides stem
Classify	State oxide type with reason	”Classify aluminium oxide.”
Write an equation	Balanced reaction	”Write the equation for CaO reacting with HCl.”
Explain	Link to acid/base behaviour	”Explain why CO₂ is an acidic oxide.”
Give an example	Named oxide of stated type	”Give an example of an amphoteric oxide.”
Predict	Oxide type from element position	”Predict whether the oxide of magnesium is acidic or basic.”

Worked exam-style stems (how to answer the wording)

1. “Classify aluminium oxide and write equations to show its reaction with both hydrochloric acid and sodium hydroxide.” Al₂O₃ is amphoteric — it reacts with both acids and bases.
   Al₂O₃ + 6HCl → 2AlCl₃ + 3H₂O
   Al₂O₃ + 2NaOH → 2NaAlO₂ + H₂O
   Mark-scheme reward: amphoteric + correct equations with both acid and base.
2. “Explain why carbon dioxide is classified as an acidic oxide.” CO₂ reacts with alkalis (e.g. Ca(OH)₂) to form a salt (CaCO₃) — this is characteristic of an acidic oxide. Reward: reacts with alkali + salt formed.
3. “Write the equation for the reaction of copper(II) oxide with dilute sulfuric acid.” CuO + H₂SO₄ → CuSO₄ + H₂O. Reward: correct salt + water.

When you can recognise the wording instantly, work the full set on the Acids, Bases and Salts topical past paper questions and the Oxides quiz to lock the patterns in.

How oxides connect to the rest of the syllabus

Oxides link to Characteristic Properties of Acids and Bases (acid + metal oxide reactions), Preparation of Salts (insoluble salt preparation) and The Periodic Table (oxide trends across periods). When you are ready to mix topics, the Cambridge IGCSE Chemistry resource hub links every Acids, Bases and Salts subtopic.

Common mistakes students make

• Calling all metal oxides basic (Al₂O₃ and ZnO are amphoteric).
• Calling all non-metal oxides acidic (CO and H₂O are neutral).
• Forgetting that amphoteric oxides react with both acids and bases.
• Writing CO₂ + NaOH → Na₂CO₃ without balancing or omitting water where required.
• Confusing basic oxide with base — a basic oxide reacts with acid but may be insoluble.

When you need more support

If oxides questions keep costing marks — especially amphoteric classification — work through the Acids, Bases and Salts topical past paper questions and the Oxides quiz, then get focused help from a Cambridge IGCSE Chemistry tutor.

Frequently asked questions

Are oxides hard in Cambridge IGCSE Chemistry? Classification follows clear rules. Marks are lost when students forget amphoteric oxides or misclassify CO and H₂O.

What is an amphoteric oxide? An oxide that reacts with both acids and bases. At IGCSE, know Al₂O₃ and ZnO.

Why is CO₂ an acidic oxide? It reacts with alkalis to form a salt (and water), which is the defining behaviour of an acidic oxide.

How do I revise oxides effectively? Learn the classification table, write equations for each oxide type, then take the Oxides quiz.

Ready to master Cambridge IGCSE Chemistry oxides?

Start with the Oxides subtopic page, then book a free trial with a Cambridge IGCSE Chemistry specialist to turn oxides into guaranteed marks.

Ready to Excel in Your Studies?

Get personalised help from Tutopiya's expert tutors. Whether it's IGCSE, IB, A-Levels, or any other curriculum — we match you with the perfect tutor and your first session is free.

Book Your Free Trial