1. Do now! Can you continue the questions you started last lesson?

2. Today’s lesson Use the term half-life in simple calculations, including the use of information in tables or decay curves. Give and explain examples of practical applications of isotopes.

3. Do now! Tomekitis

4. ½ - life This is the time it takes half the nuclei to decay half-life (t ½ ) Number of nuclei undecayed time A graph of the count rate against time will be the same shape

5. Different ½ - lives Different isotopes have different half-lives The ½-life could be a few milliseconds or 5000 million years! half-life (t ½ ) Number of nuclei undecayed time

6. Examples A sample of a radioactive isotope of half life 2 hours has a count rate of 30 000 counts per second. What will the3 count rate be after 8 hours?

7. Examples

8. Uses of radioactive isotopes

9. Used as Tracers

12. Killing microbes

14. Thickness control

16. Smoke detection

17. Checking welds

18. Carbon dating

19. Summary sheet

20. “Can you………?”

21. Test! Wednesday 16 th March (11X) Monday 21 st March (11A)

22. Can you answer the questions on pages 261 and 265?