1. RADIOACTIVITY Radioactive Decay

2. T HE A TOM

3. T YPES OF R ADIOACTIVE D ECAY T YPES OF R ADIOACTIVE D ECAY 1. Alpha Decay: The transmutation of and atom with an emission of an alpha particle 2. Beta Decay: The transmutation of and atom with an emission of a beta particle 3. Gamma Decay: The nucleus of an atom settles to a lower energy state and releases electromagnetic energy (photon)

4. A LPHA D ECAY  An alpha particle (  ) is a helium nucleus, a cluster of two protons and two neutrons

5. B ETA D ECAY  In beta decay (  ) a neutron decays into a proton, an electron and an antineutrino  The beta particle is an electron  Neutrinos are particles 10 millionths the mass on an electron with no charge.

6. G AMMA D ECAY  In gamma decay (  ) a nucleus settles to a lower energy state and release a photon  The gamma particle is a photon

7. R EACTION E XAMPLES 1. Find the daughter nucleus for the beta decay of thorium-234. 2. Predict the daughter nucleus that results from alpha decay of radium-226.

8. NUCLEAR PROCESSES Fission & Fusion

9. F ISSION VS. F USION

10.  In nuclear fusion, two nuclei combine to form a more massive nucleus.  Fusion means the merging together of different elements to make a new element.  In nuclear fission, a massive nucleus splits into two lighter nuclei.  Fission means breaking something up into parts.

11. L AW OF C ONSERVATION OF M ASS -E NERGY  Mass can be transformed into energy and energy can be transformed into mass.  This explains the mass defect: when nucleons are bound together, their energy is reduced, so their mass is also reduced.  The binding energy of a nucleus is the mass-energy equivalent of its mass defect.

12. N UCLEAR R EACTIONS

13. N UCLEAR F ISSION Fission is the reaction in which a massive nucleus splits into two or more lighter nuclei. 1. Spontaneous Fission: Spontaneous fission occurs when an unstable isotope splits into two or more smaller nuclei without any external interaction.  It is only seen in nuclei with atomic mass numbers above 230 (elements near thorium).  Induced Fission: a nucleus absorbs a neutron, forming a highly unstable isotope that breaks up almost instantly into two lighter nuclei

14. N UCLEAR F ISSION Thorium-230 decays to polonium-218 by three alpha decays. Write the equations for the reactions. Use a periodic table.

15. N UCLEAR F ISSION

16. N UCLEAR F USION The dominant fusion reaction in stars the size of our Sun or smaller is the proton-proton chain.

17. N UCLEAR F USION Another form of fusion is neutron absorption.