1. Need to know
Historical outline of radioactivity: work of Becquerel (discovery of radiation from uranium salts); Marie and Pierre Curie (discovery of polonium and radium).
Widespread occurrence of radioactivity.

2. Antoine Henri Becquerel
In 1896, while investigating uranium salts, Becquerel accidentally discovered radioactivity . Becquerel found that the photographic plates were fully exposed when in contact with radioactive salt.

3. Marie Curie
developed a theory of radioactivity techniques for isolating radioactive isotopes, and discovered two new elements, Polonium and Radium

4. Natural Radiation comes from
Sources in the earth that contain radioactive isotopes.
Sources from space in the form of cosmic rays
Sources in the atmosphere, particularly from Radon gas that is released from the Earth's crust.
About 15% of background radiation comes from medical X-rays and nuclear medicine.
About 3% of background radiation comes from other man-made sources such as: nuclear testing, power plants, and smoke detectors.

5. Pierre Curie
Pierre discovered nuclear energy, by identifying the continuous emission of heat from Radium particles. He also investigated the radiation emissions of radioactive substances, which lead to the discovery of Alpha, Beta and Gamma radiation.

6. Radioactivity
Is the spontaneous breaking up of unstable nuclei with the emission of one or more types of radiation
There are three types alpha, beta and gamma

7. Alpha particle

8. Alpha Made of 2 protons + 2 neutrons Helium nucleus
From unstable nuclei
Low penetration; stopped by a sheet of paper
Americum-241 [used in smoke detectors] emits alpha particles

9. Alpha particle

10. Smoke detector

11. Beta
Electrons
Formed when a neutron decays into a proton and an electron
Penetrate 5mm of aluminum
Carbon-14 used in carbon-dating emits beta particles

12. Neutron decay

13. Carbon 14

14. Learning Outcomes Alpha, beta and gamma radiation (nature and
penetrating ability).One example each of:
an α-emitter, e.g. 241Am
a β-emitter, e.g. 14C
a γ-emitter, e.g. 60Co.

15. Need to know Uses of radioisotopes (three examples).
14C age determination (calculations not required).
60Co for cancer treatment.
Food irradiation.

16. The animation below shows the decay of a radioactive sample of Carbon-14 to stable Nitrogen by the emission of beta particles.

17. Carbon-14 decays to nitrogen-14

18. Take in Carbon-14
The percentage of carbon-14 in all of these living things is the same as the percentage of carbon-14 in the atmosphere.

19. Death
The carbon-14 within every once-living thing will someday turn back into nitrogen-14

20. Carbon-14 detection

21. Gamma High energy electromagnetic radiation
Not deflected by magnetic or electric fields
Only stopped by several cms of lead.
Cobalt-60 [used to treat cancer] emits gamma rays

22. Gamma Rays

23. Penetration

24. Penetration 2

25. Need to know
Distinction between chemical reaction and nuclear reaction
(simple equations required –confine examples to alpha and beta emissions).

26. Nuclear reactions Emission of radioactive radiation
In a nuclear reaction the nucleus forms a new element,

27. Loss of an alpha particle
Radium-226 Radon alpha particle
22688Ra22286Rn +42He
Mass decreases by 4 [226222]
Atomic number decreases by 2 [8886]

28. Beta loss Carbon-14 nitrogen-14 + beta 146C  147N + 0-1e
Mass number stays the same
Atomic number increases by 1

29. Radioisotopes
A Radioisotope (radionuclide) is an atom with an unstable nucleus.

30. Transmutation Change of one element into another
Rutherford confirmed the artificial transmutation of nitrogen. Alpha particles were allowed to pass through nitrogen gas; when one struck a nitrogen nucleus, a hydrogen nucleus was ejected, and an oxygen nucleus formed.

31. Half life
Time taken for half of the nuclei in any given sample to decay

32. uses Medical—.gamma rays kill cancerous cells and sterilises equipment
Archaeological—after a living thing dies the amount of C-14 decreases. Used to determine the age of a plant/animal
Food—gamma rays kill disease causing organisms