5-RAD-02

Outcomes

• Pupils can define and understand the term 'activity' and state its unit - becquerel(Bq)
• Pupils define 'half-life'
• Pupils can use graphs to determine half-life

Specification References

• 7.10 understand that the activity of a radioactive source decreases over a period of time and is measured in becquerels
• 7.11 recall the term 'half-life' and understand that it is different for different radioactive isotopes
• 7.12 use the concept of half-life to carry out simple calculations on activity

Starter

Tell pupils that they'll be playing a game today. Show them the pots with dice and start a short discussion about how gambling, winning the lottery is all relative and RANDOM.

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!