1. Nuclear Reactions

2. Going Nuclear A nuclear reaction is a reaction in which there are changes to the nuclei of the atoms involved. This differs from previous reactions which only involved the transfer or sharing of valence electrons. It’s still a type of chemical reaction so we will see new substances created with new properties. There are a couple of differences between nuclear reactions and the traditional chemical reactions: –Nuclear reactions are unaffected by temperature, pressure or catalysts. –An atom that is undergoing a nuclear reaction will do so as part of any compound and once it has started – it’s on!

3. Atoms Falling Apart? As atoms get larger – they have more protons in the nucleus. All of these positively charged protons are trying to repel each other, but, the neutrons get in there and space them far enough apart so they are able to stand being so close to one another. There is a limit though…beyond Bismuth (83) it seems that the nucleus has too much positives and the repulsion is just too much. Elements beyond Bismuth occur only as radioactive isotopes. Radioactivity, if you remember, is the energy released by an atom breaking down into a more stable isotope – this process of breaking down is known as radioactive decay.

4. Radiation When an atom undergoes radioactive decay, radiation and energy are released along with the leftovers of the decaying atom. There are several types of radiation that differ in the type of particle that is released form the atom and the strength/severity of the energy that is emitted. The types of radiation that we will be examining in class are: –Alpha (α) radiation –Beta (β) radiation –Gamma (γ) radiation

5. Alpha (α) Radiation Alpha radiation occurs when a stream of helium nuclei is emitted from a radioactive source. The helium nuclei consist of two protons and two neutrons and is termed an alpha particle. Alpha radiation is substantially weaker than the other types of radiation. It can be stopped by paper or clothing.

6. Alpha (α) Radiation

7. Beta (β) Radiation Beta radiation consists of fast moving electrons (e – ). A beta ray is stream of electrons of beta particles. Beta radiation is stronger than alpha radiation. It can penetrate paper and clothing. It can embed itself about 4mm into body tissues.

8. Beta (β) Radiation

9. Gamma (γ) Radiation Gamma radiation is high energy electromagnetic radiation given off by a radioisotope. Gamma rays are often emitted along with alpha and beta rays as a radioactive atom disintegrates. Gamma rays have no mass so they travel the fastest and have the greatest penetrating ability of the three types of radiation. Gamma rays also made the Incredible Hulk!

10. Gamma (γ) Rays

11. Types of Radiation

12. Types of Nuclear Reactions Nuclear fusion – Reaction in which nuclei combine to produce a nucleus of greater mass. Solar fusion – Reaction in which hydrogen nuclei (protons) fuse to make a helium nucleus. (You also need a couple of beta particles for this.) Nuclear fission – reaction in which the nucleus of an atom is split into two smaller fragments of nearly equal mass.

13. THE END!