Year 7 · Science

Conservation of mass: Year 7 introduction

6 checked activities 1 video matches

Start here

Focus on law of conservation of mass explained. Start with “Apply the Law of Conservation of Mass to Solve Calculations”, then explain the idea in your own words.

Understand the key idea

In a chemical reaction, atoms are rearranged but never created or destroyed, so the total mass of the products equals the total mass of the reactants. The same is true for changes of state, because the particles are unchanged and only their arrangement differs.

Common mix-up

When a mass appears to fall — such as wood burning away — no mass has been lost. Gases have escaped to the surroundings, and mass only appears constant when the reaction is done in a sealed container.

Try this first

Balance a simple equation and count atoms on each side.
Explain why a burning candle seems to lose mass.
Predict the mass reading if the same reaction runs in a sealed flask.

Ask: If a log burns down to a little ash, where did the rest of it go?

Year 7 learners practise law of conservation of mass explained.

The activities include Apply the Law of Conservation of Mass to Solve Calculations, Find Out About the Law of Conservation of Mass, Learn About the Conservation of Mass in Chemical Reactions, and related practice. The checked support below includes video, teaching, worksheet, lesson. Open a resource in its provider's website and choose the format that best helps the learner explain the idea independently.

Activities covered

Apply the Law of Conservation of Mass to Solve Calculations
Find Out About the Law of Conservation of Mass
Learn About the Conservation of Mass in Chemical Reactions
Learn About the Conservation of Mass in Simple Reactions
Study the Conservation of Mass in Chemical Reactions
Use the Law of Conservation of Mass to Calculate Reactants and Products in Chemical Reacti ...

Learning path

These same-subject links were reviewed as the foundations for this topic and the learning it directly unlocks.

Learn this first

Year 7The particle model: Year 7 KS3 introduction
Provides the idea that matter is made from particles which can move without disappearing.
Year 7Types Of Chemical Reactions
Introduces chemical reactions before total reactant and product mass is compared.

Where this leads next

Year 8Rearrangement Of Atoms In Reactions
Explains conservation by showing that atoms are rearranged rather than created or destroyed.
Year 8Conservation Of Mass
Applies the same principle to more varied reactions and open-system observations.

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