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

Give pupils the mini white boards and ask them to draw the plum pudding model of the atom. Discuss their drawings.

Ask them to recall the Geiger and Marsden experiment. Discuss.

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!