Year 10 Science · Unit 2 · Lesson 26
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Learning Goals
Odd one out
Circle the item that does not belong in each group. Then explain why it doesn't fit in the answer column.
| # | Group | Odd one out + reason |
|---|---|---|
| 1 | Fission Chain reaction Uranium-235 Helium | |
| 2 | Deuterium Tritium Hydrogen Plutonium | |
| 3 | The Sun Stars Fusion Nuclear reactor | |
| 4 | Splitting Heavy nucleus Joining Two smaller nuclei | |
| 5 | Neutron Proton Electron Combustion |
Scenario: a fission chain reaction in a nuclear reactor
Inside a reactor, a uranium-235 nucleus absorbs a slow-moving neutron and splits, following the equation 23592U + 10n → 14156Ba + 9236Kr + 310n. Each split releases two or three fast neutrons that can go on to split other uranium nuclei. Control rods are used to absorb some of the neutrons so that the reaction does not run out of control.
| Process Is this fission or fusion? What is the key event that happens to the uranium nucleus? |
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| Check the equation Add up the top numbers (mass) on each side, then the bottom numbers (atomic). Show they balance. |
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| Chain reaction Explain how the neutrons released cause a self-sustaining chain reaction. |
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| Control rods Why are control rods needed, and what would happen without them? |
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| Fission vs fusion Name one way a fusion reaction (such as in the Sun) would differ from this fission reaction. |
Wrap Up
In one sentence, explain why a fission chain reaction must be carefully controlled in a power reactor but is uncontrolled in an atomic bomb.