Reactants and products | Structure strip

Structure strips can be used to promote independent writing. Learners write about chemical reactions using key terms, identify the difference between chemical and physical changes and explain types of chemical reactions. 

Learning objectives

1. Identify the reactants and products in a chemical equation.
2. Identify whether a chemical or physical change is occurring.
3. Define reactions as combination or decomposition from word and symbol equations.

Introduction

Chemical reactions are when one or more new substances are formed from other substances. This can also be referred to as a chemical change. In a physical change no new substances are formed, for example a change of state or dissolving.

A chemical change can occur through two types of reaction.

• A combination reaction (also known as a synthesis reaction) is where two or more reactants chemically change into one or more products
• A decomposition reaction is where a compound breaks down to give two or more products.

In chemical reactions, the reactants are the chemicals that react together and are found before the arrow in a word equation. The products are the new substances produced and are found after the arrow in a word equation.

How to use structure strips

Structure strips are a type of scaffolding you can use to support learners to retrieve information independently. Use them to take an overview at the start of the topic, to activate prior knowledge, or to summarise learning at the end of a teaching topic. For more ideas on how to use structure strips with your learners, visit 5 ways to use structure strips effectively. 

Structure strips have sections containing prompts, sized to suggest the amount that learners must write. Learners glue the strips into the margin of an exercise book and write their answers next to the sections, in full sentences. When learners have finished using the structure strip, they should have an A4 page set of notes and examples.

The strips are printed five to a page and will need to be trimmed to size. Find them on the second page of the student sheet.

Scaffolding

• Encourage learners to use the suggested key words and phrases in their answers.
• To further support learners, include additional prompts in the structure strip. If learners are struggling to engage with the task, supply them with sentence starters created from the model answers.
• As learners grow in confidence, ask them to attempt the extension question first and then use the structure strip to improve or self-assess their answer.

Key words

Reactants, products, chemical reaction, chemical change, combination reaction, decomposition reaction. 

Metacognition

This resource supports learners to develop their metacognitive skills in three key areas.

• Planning: the strips provide scaffolding to plan the written response. Learners will decide where to gather information from (textbooks, own notes, revision websites). Ask learners: is the source of information you are using reliable?
• Monitoring: learners are prompted by the questions in the structure strip and can check their own answer against the prompts. Ask learners: have you covered all of the prompts in the space provided? Do you need to change anything to complete the task?
• Evaluation: learners can self-assess or ask a peer to check their work against the answers. Ask learners: did you achieve what you meant to achieve? What might you do differently another time?

Answers

Suggested answers for the structure strip activity are given in the downloadable teacher notes.

Answers to extension question

Due to the nature of this task, answers will vary. Some of the key points learners can include in their summary are:

• the acid contains hydrogen, sulfur and oxygen
• magnesium contains only magnesium atoms
• magnesium atoms react with the sulfuric acid
• hydrogen gas is produced
• hydrogen contains only hydrogen atoms
• magnesium sulfate is formed
• magnesium sulfate contains magnesium, sulfur and oxygen
• bubbles or fizzing are observed
• a chemical change has occurred.

Learners can use these bullet points to self-assess or improve their answer. You can also supply them to less confident learners who need additional guidance.