When a substance decomposes it undergoes a decomposition reaction.

A type of reaction in which a reactant compound breaks down into two or more products.

Chemical reactions: decomposition

Science

Characteristics of chemical reactions

Conservation of mass and balanced symbol equations

Chemical reactions: oxidation

Chemical reactions: combustion

Chemical reactions: precipitation

In the Acids and Bases unit, pupils will build on their understanding of chemical reactions to learn about the properties of acids, bases, alkalis, and the neutralisation reaction.

In the Atoms, Elements and Compounds unit, pupils learned about atoms, elements, and compounds and how particles reorganise in a chemical reaction.

This unit covers the conservation of mass in changes of state and chemical reactions, including atom rearrangement. It also focuses on representing reactions with formulae and equations, exploring combustion, decomposition, and displacement, and distinguishing chemical from physical changes.

Understanding chemical reactions

Physical activity and equipment requiring safe use

A reaction where two compounds combine to form one product.

A reaction where a single compound breaks down into two or more products.

A reaction where a gas is produced by combining liquids.

Decomposition reactions usually require {{}}, light, or electricity to occur.

What gas is commonly produced when metal carbonates decompose?

Which of the following is a decomposition reaction?

When metal carbonates decompose upon heating, they typically form metal {{}} and carbon dioxide gas.

Which of the following reactions represents the decomposition of water?

What are common signs that a chemical reaction is taking place?

In a chemical reaction, what happens to the atoms of the reactants?

What happens to the mass of the products compared to the mass of the reactants in a chemical reaction?

What type of reaction involves a substance combining with oxygen?

To test for carbon dioxide, you would bubble the gas through {{}}. If carbon dioxide is present, the solution turns milky (cloudy).

Which of the following chemicals are reactants in this reaction?
zinc + hydrochloric acid → zinc chloride + hydrogen

Chemical reactions: decomposition

Lesson outcome

Content guidance