Year 10 Science · Unit 2 · Lesson 26

Nuclear Fission and Fusion

Foundation Worksheet

Name

Date

Class

Learning Goals

Recall what happens during nuclear fission and nuclear fusion.
Sort key features into the correct process: fission or fusion.
Explain why nuclear reactions release so much more energy than chemical reactions.

Warm Up

Fill the gap

Choose the correct word from the word bank to complete each sentence. Two words will NOT be used.

fission fusion neutron chain reaction uranium helium energy Sun electron oxygen

When a heavy nucleus splits into two smaller nuclei, the process is called nuclear . This usually begins when the nucleus absorbs a . A common fuel for this process is -235. The extra neutrons released can split more nuclei, causing a self-sustaining . When light nuclei join together to form a heavier nucleus, the process is called nuclear , and it often produces gas. Fusion powers the and other stars. Both processes release a huge amount of because a tiny amount of mass is converted following E = mc².

Your Turn

Sort it!

Write each feature from the pool into the correct process box below. Each feature belongs to exactly one process.

Heavy nucleus splits apart Light nuclei join together Uses uranium-235 as fuel Uses hydrogen isotopes as fuel Powers the Sun and stars Used in nuclear power reactors Produces helium Can cause a chain reaction Needs extreme temperature and pressure Triggered by absorbing a neutron Not yet a practical power source on Earth Produces radioactive waste

Nuclear Fission

Nuclear Fusion

Show What You Know

1. In your own words, describe what happens to a uranium-235 nucleus during nuclear fission. Mention the neutron, the smaller nuclei, and the energy released.

Recall 2 marks

2. Name the process that powers the Sun and write down two conditions that are needed for it to happen.

Recall 2 marks

Wrap Up

In one sentence, explain why nuclear reactions release millions of times more energy than chemical reactions such as burning fuel.