5-RAD-04

Specification References

• 7.17 understand that a nucleus of U-235 can be split (process of fission) by collision with a neutron, and that this process releases energy in the form of kinetic energy of the fission products
• 7.18 recall that the fission of U-235 produces two daughter nuclei and a small number of neutrons
• 7.19 understand that a chain reaction can be set up if the neutrons produced by one fission strike other U-235 nuclei
• 7.20 understand the role played by the control rods and moderator when the fission process is used as an energy source to generate electricity

Main Body of Lesson

• Explain in detail how Geiger and Marsden's experiment led to the current structure of the atom:

- most alpha particles going through - empty space between the nucleus and the orbit of electrons; - some alpha particles being deflected - nucleus posivively charged; - alpha particles bounced back - nucleus very dense, carries the whole mass of the atom;

• Introduce pupils to the symbol A¦Z X and define Z and A: Z = atomic number = number of protons inside the nucleus; A = atomic number = number of nucleons inside the nucleus.
• Introduce the three types of radiation and pupils must understand that all three types are emitted when the nucleus is unstable.
• Describe the nature of each type of radiation in terms of:

-what is made of - How is charged - range in air - speed at which it travels at -what stops it (A table containing all info in Science shared)

• use the kit containg all three sources, the Geiger-Muller counter and test them in terms of penetration (what can they be stopped by)

Plenary

• alphs, beta and gamma rays are ionising radiations emitted from unstable nuclei in a random process

Additional Information

Resources Required

• Geiger-Muller counter
• kit containing alpha, beta and gamma sources
• different materials of different thicknesses

Safety/Hazards

• Don't keep the sources outside their boxex for too long!