Science Year 9 - Unit 2 - Lesson 6

Electron Arrangement and Stability

Use this worksheet after reading the lesson to practise the key ideas and prove you can meet the success criteria.

Name

Date

Class

1. Key Ideas

The Materials unit now moves below the visible level of materials into the atomic ideas that help explain why substances behave differently. This lesson introduces outer-shell electrons and the idea of stability, which are the foundation for valency, ions and bonding.

electrons are arranged in shells around the nucleus
atoms do not all have the same outer-shell arrangement

2. Success Criteria

By the end, you should be able to:

electrons are arranged in shells around the nucleus
outer-shell electrons are especially important in chemical behaviour
Stage 5 uses noble gas configuration as the model of stability

3. Key Terms

Electron arrangementThe way electrons are organised around the nucleus in shells or energy levels.

Outer shellThe outermost occupied shell of electrons in an atom.

Valence electronAn electron in the outer shell that is important in bonding and reactivity.

StableLess likely to react or change because the outer-shell arrangement is already favourable.

Noble gas configurationA particularly stable outer-shell arrangement used as the Stage 5 model of stability.

Shell modelA simplified model showing electrons arranged in shells around the nucleus.

4. Activity: Build the Lesson Map

Use the lesson to complete the table. Keep answers brief but specific.

Prompt	Your answer
Main concept
Important example
Common mistake to avoid
How this links to the next lesson

5. Short Answer Questions

1. Explain this lesson goal in your own words: "electrons are arranged in shells around the nucleus". Use one specific example from the lesson.

Core

2. Apply this idea to a new example: "outer-shell electrons are especially important in chemical behaviour". Show your reasoning clearly.

Core

3. Analyse why this idea matters for understanding Electron Arrangement and Stability: "Stage 5 uses noble gas configuration as the model of stability".

Reasoning

6. Extend: Apply the Idea

A student says, "I understand Electron Arrangement and Stability because I memorised the definition."

Explain why memorising a definition is not enough. Use an example from the lesson to show deeper understanding.

7. Multiple Choice

1. What is the best first step when answering a question about Electron Arrangement and Stability?

A. Identify the key concept being tested

B. Write every fact from memory

C. Ignore the command word

D. Skip examples and evidence

2. Which answer would show stronger understanding of Electron Arrangement and Stability?

A. An answer with accurate terms and reasoning

B. A copied definition only

C. A single-word response

D. An answer with no example

3. What should you do if a question asks you to explain?

A. Link the idea to a reason or cause

B. List unrelated facts

C. Only draw a diagram

D. Write the shortest possible answer

8. Success Criteria Proof

Finish with evidence that you can do each success criterion.

Success criterion 1

Prove that you can: electrons are arranged in shells around the nucleus

Success criterion 2

Prove that you can: outer-shell electrons are especially important in chemical behaviour

Success criterion 3