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Flashcards in Nuclear Fission Deck (14):

What is nuclear fission?

The splitting of a large nucleus to release two or more smaller nuclei and two or three neutrons, which produces energy


When is Fission most likely to happen?

If a nucleus absorbs a neutron


What might happen to the smaller nuclei produced in nuclear fission?

They can be unstable and decay


When is the fission process used?

In a nuclear power station to heat water to produce steam to drive turbines and generators to power things


What is a chain reaction?

When one reaction triggers the next


How is Nuclear fission a chain reaction?

You need a neutron to start a fission reaction, but the reaction also produces neutrons


How do engineers control chain reactions in a nuclear power station?

They use materials to absorb some of the neutrons, if the mass of radioactive material is very small, the neutrons escape so the reaction stops


What is nuclear fusion?

The joining of two lighter nuclei to form a larger nucleus, which releases energy


How is energy transferred from a nuclear store in nuclear fusion reactions?

Heating and electromagnetic radiation


What is the problem with trying to join two nuclei together?

All nuclei have the same charge, when you bring two protons together they repel each other


Why do most fusion reactions involve isotopes of hydrogen?

You can fuse two protons together to make deuterium (hydrogen-2). You can then fuse deuterium to form tritium (hydrogen-3) and hydrogen
The hydrogen-2 and hydrogen-3 fuse to form a helium nucleus and neutron


What are the conditions in the sun that mean fusion reactions are possible?

High temperatures - nuclei are moving at high speeds
High pressures - keep the nuclei close enough to fuse


Where does the energy come from for Fusion reactions?

Mass of products is slightly smaller than the mass of reactants, the tiny amount of mass produces an extremely large amount of energy in the form of radiation


How can you calculate the energy in fusion reactions

Energy = change in mass x speed squared
E = mc^2