1. Higher Unit 3 Radioisotopes

2. After today’s lesson you should be able to:  Give four uses of radioisotopes.  Explain the difference between ‘fission’ and ‘fusion’.  Give advantages and disadvantages of nuclear fuels compared to fossil fuels.  Explain how elements are created.  Give the name of the source where all naturally occurring elements are formed.

3. Uses of radioisotopes  Radioisotopes are used in: 1. Medicine Cobalt – 60 is used in the treatment of tumours. Cobalt – 60 is used in the treatment of tumours. Phosphorus - 32 is used in the treatment of skin cancers. Iodine –132 and iodine –123 are used to investigate possible disease of the thyroid gland.

4. 2.Industry Cobalt – 60 and iridium-192 are used to examine welds for imperfections. Flow patterns in estuaries and leaks in pipelines can be investigated using small quantities of short half-life isotopes. 3.Scientific research Carbon-14 is used to date archeological specimens between 600 and 10000 years old.

5. 4.Energy production Nuclear energy is produced by nuclear fission of uranium nuclei. This involves splitting the nuclei by bombarding them with slow-moving neutrons. There is ongoing research into energy production from nuclear fusion. However, there is difficulty in joining nuclei together due to the repulsions of the protons when the nuclei are brought together.

6. Nuclear fuels vs Fossil fuels Advantages  No greenhouse or acid rain gases emitted.  Uranium is a finite supply. Disdavantages  Low possibility of a disastrous accident (e.g. Chernobyl)  Contribute to background radiation  Difficulty in disposing of used radioactive fuel.

7. The origin of the elements  Nuclear fusion reactions only occur at very high temperatures e.g. those found in the Sun and in the stars.  These temperatures are required for nuclei fusion to take place i.e. the nuclei collide with such force at the temperatures that the repulsive energy barrier between the protons can be overcome.  Nuclear fusion reactions of elements take place in the gas clouds of stars. The energy released causes the gas cloud to glow.

8.  Two hydrogen nuclei fuse to form helium.  The helium nuclei can then fuse to form other elements.  All naturally occurring elements, including those in our bodies, originated in the stars.  Neil Degrasse Tyson The Elements: Forged in Stars – YouTube Neil Degrasse Tyson The Elements: Forged in Stars – YouTube Neil Degrasse Tyson The Elements: Forged in Stars – YouTube  Birth of the Universe 1 - 5: Part 1 - YouTube Birth of the Universe 1 - 5: Part 1 - YouTube Birth of the Universe 1 - 5: Part 1 - YouTube

9. Man-made elements  All elements with atomic numbers higher than uranium have been man-made by bombarding heavy nuclei with high energy particles.  All of these synthetic elements are radioactive.