Year 8 - Science
Characteristics of chemical reactions
Understanding chemical reactions
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This pupil-friendly study guide includes a unit summary, clear notes, common mistakes, and quick questions with answers.
Unit Summary
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.
Lesson Summary
You will learn to describe some of the changes that indicate a chemical reaction is taking place.
Key Notes
- Characteristics of chemical reactions include changes in colour, bubbling, or a change of temperature.
- Bubbles appear when a gas is produced in a chemical reaction.
- In a chemical reaction, atoms rearrange themselves to form new substances.
- Generally, chemical reactions are irreversible.
Vocabulary To Learn
- chemical reaction: when atoms are rearranged to make new products and changes can be observed e.g. bubbles of gas forming.
- irreversible reaction: occurs in one direction only where the reactants are converted into the products.
- reactants: elements or compounds before a reaction takes place. Reactants are found on the left hand side of a chemical equation.
- products: elements or compounds that are formed after a reaction has taken place. Products are found on the right hand side of a chemical equation.
Common Mistakes To Avoid
- Pupils do not understand chemical reactions as changes, they considered them to be 'events'. They focus on observable features e.g. colour change rather than formation of a new substance.
3 Quick Questions (With Answers)
1. Explain the scientific idea in this lesson using two key points.
Characteristics of chemical reactions include changes in colour, bubbling, or a change of temperature. Bubbles appear when a gas is produced in a chemical reaction.
2. Define this scientific word and use it in context. 'chemical reaction'
when atoms are rearranged to make new products and changes can be observed e.g. bubbles of gas forming. Include the word in a full scientific explanation, not as a single label.
3. Correct this common scientific misunderstanding.
Mistake: Pupils do not understand chemical reactions as changes, they considered them to be 'events'. They focus on observable features e.g. colour change rather than formation of a new substance. Correction: Use questioning to encourage pupils to make links between their observations as evidence that a new substance is formed when substances undergo chemical reactions.
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