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TN-CHEM-ACT-61001 · v2.-7

Isotopes

ACT · Chemistry · Atomic Structure · Edexcel

Grade

ACT

Subject

Chemistry

Topic

Atomic Structure

Subtopic

Isotopes

Curriculum

Edexcel

Difficulty

Core

Time

25 minutes

Total marks

54

Student name

Teacher name

Date

Learning objectives

  • Recognise isotopes accurately in chemistry contexts.
  • Explain the underlying rule of isotopes in the student's own words.
  • Apply isotopes to multi-step and unfamiliar problems.
  • Justify a chosen method and identify errors in another student's work.

Skills assessed

  • Fluency and recall
  • Method and setting out
  • Reasoning and justification
  • Problem solving in context
  • Self-assessment

Instructions

  1. Write your name, your teacher's name and the date in the header.
  2. Answer every question in the space provided. Continue on the back if needed.
  3. Show all working — method marks are awarded even when the final answer is wrong.
  4. Aim to finish in about 25 minutes.
  5. Complete the reflection box at the end before you hand the sheet in.

Warm-up

Bloom: Remember · 4 marks

Answer quickly. These check you are ready for the topic.

  1. 1.Name one fact you already know about isotopes.

    [1]
  2. 2.State one fact you already know about isotopes.

    [1]
  3. 3.Name one fact you already know about isotopes.

    [1]
  4. 4.State one fact you already know about isotopes.

    [1]

Recall

Bloom: Remember · 4 marks

Complete from memory. No calculator, no notes.

  1. 1.Label the key term used in isotopes described here: item 1.

    [1]
  2. 2.Label the key term used in isotopes described here: item 2.

    [1]
  3. 3.Complete the key term used in isotopes described here: item 3.

    [1]
  4. 4.Complete the key term used in isotopes described here: item 4.

    [1]

FreeMathWorksheet · TN-CHEM-ACT-61001 · v2.-7

© 2026 FreeMathWorksheet. Licensed for classroom and home use. Redistribution or resale is not permitted.

Page 1 of 4

FreeMathWorksheet · ACT Chemistry

Isotopes

Basic Practice

Bloom: Understand · 5 marks

Work through each item. Show the step you used.

  1. 1.Work out part 1 using the rule for isotopes.

    [1]
  2. 2.Match part 2 using the rule for isotopes.

    [1]
  3. 3.Match part 3 using the rule for isotopes.

    [1]
  4. 4.Identify part 4 using the rule for isotopes.

    [1]
  5. 5.Work out part 5 using the rule for isotopes.

    [1]

Guided Practice

Bloom: Understand · 8 marks

The first step is given. Finish the reasoning.

  1. 1.Complete the method for part 1. Step 1 has been started for you.

    [2]
  2. 2.Complete the method for part 2. Step 1 has been started for you.

    [2]
  3. 3.Continue the working for part 3. Step 1 has been started for you.

    [2]
  4. 4.Continue the working for part 4. Step 1 has been started for you.

    [2]

FreeMathWorksheet · TN-CHEM-ACT-61001 · v2.-7

© 2026 FreeMathWorksheet. Licensed for classroom and home use. Redistribution or resale is not permitted.

Page 2 of 4

FreeMathWorksheet · ACT Chemistry

Isotopes

Independent Practice

Bloom: Apply · 10 marks

No scaffolding. Set out your full method.

  1. 1.Calculate part 1 on isotopes without help.

    [2]
  2. 2.Calculate part 2 on isotopes without help.

    [2]
  3. 3.Work out fully part 3 on isotopes without help.

    [2]
  4. 4.Calculate part 4 on isotopes without help.

    [2]
  5. 5.Calculate part 5 on isotopes without help.

    [2]

Challenge Questions

Bloom: Analyse · 9 marks

Harder items. Attempt every one, even partially.

  1. 1.Find and justify the statement in part 1 about isotopes.

    [3]
  2. 2.Show that the statement in part 2 about isotopes.

    [3]
  3. 3.Prove the statement in part 3 about isotopes.

    [3]

FreeMathWorksheet · TN-CHEM-ACT-61001 · v2.-7

© 2026 FreeMathWorksheet. Licensed for classroom and home use. Redistribution or resale is not permitted.

Page 3 of 4

FreeMathWorksheet · ACT Chemistry

Isotopes

Real-life Application

Bloom: Apply · 6 marks

Use the skill in context. State units in your answer.

  1. 1.Use the information to decide a real chemistry situation that depends on isotopes.

    [3]
  2. 2.In context, work out a real chemistry situation that depends on isotopes.

    [3]

Critical Thinking

Bloom: Evaluate · 8 marks

Explain your reasoning in full sentences.

  1. 1.Compare and justify a student's method for isotopes is or is not efficient.

    [4]
  2. 2.Evaluate whether a student's method for isotopes is or is not efficient.

    [4]

Reflection

Bloom: Create · 0 marks

Not marked. Answer honestly — this guides your next worksheet.

  1. 1.Describe how confident you feel with isotopes and what you will practise next.

    [—]
  2. 2.Reflect on how confident you feel with isotopes and what you will practise next.

    [—]

FreeMathWorksheet · TN-CHEM-ACT-61001 · v2.-7

© 2026 FreeMathWorksheet. Licensed for classroom and home use. Redistribution or resale is not permitted.

Page 4 of 4