1. Created by C. Ippolito May 2007 Nuclear Chemistry Objectives: 1. E xplain how unstable nuclei release energy 2. D escribe the three main types of nuclear radiation 3. S olve problems that involve half-life 4. I dentify the two ways transmutation can occur 5. D escribe what happens in a nuclear chain reaction 6. E xplain the role of water in the storage os spent fuel rods 7. D istinguish fission from fusion reactions 8. I dentify three devices used to detect radiation 9. D escribe how radioisotopes are used in medicine

2. Created by C. Ippolito May 2007 Radioactivity Antoine Becquerel, Marie and Pierre Curie Antoine Becquerel, Marie and Pierre Curie studied rays from uranium “exposed” film studied rays from uranium “exposed” film Radioactivity Radioactivity the process of “releasing” rays the process of “releasing” rays Radiation Radiation penetrating rays and particles released penetrating rays and particles released Radioisotopes Radioisotopes unstable nuclei release energy during radioactive decay unstable nuclei release energy during radioactive decay

3. Created by C. Ippolito May 2007 Types of Radiation Alpha Radiation (α) Alpha Radiation (α) two protons and two neutrons ( ) two protons and two neutrons ( ) Beta Radiation (β) Beta Radiation (β) electron ( ) or positron ( ) electron ( ) or positron ( ) Gamma Radiation (γ) Gamma Radiation (γ) high energy photon high energy photon

4. Created by C. Ippolito May 2007 Alpha Radiation Composition alpha particle He nucleus Symbol α, Charge 2+ Mass 4 amuSource Radium-226 Penetrance low 0.05 mm Shielding paper or cloth

5. Created by C. Ippolito May 2007 Beta Radiation Composition beta particle, electron Symbol β, Charge 1- Mass 1/1837 amuSource Carbon-14 Penetrance moderate 4 mm Shielding metal foil

6. Created by C. Ippolito May 2007 Gamma Radiation Composition electromagnetic radiation Symbol γ Charge 0 Mass Source Cobalt 60 Penetrance very high Shielding lead, concrete

7. Created by C. Ippolito May 2007 Nuclear Stability and Decay Nuclear Force Nuclear Force holds all nuclear particles together holds all nuclear particles together stronger than electromagnetic forces stronger than electromagnetic forces Band of Stability Band of Stability neutron to proton ratio for stable nuclei neutron to proton ratio for stable nuclei

8. Created by C. Ippolito May 2007 Half-Life Half-life (t ½ ) Half-life (t ½ ) time required for one-half of the nuclei of a radioisotope to decay to products time required for one-half of the nuclei of a radioisotope to decay to products after each half-life, half of the existing radioactive atoms have decayed into atoms of a new element after each half-life, half of the existing radioactive atoms have decayed into atoms of a new element Table N – Radioisotopes half-life half-life decay type decay type

9. Created by C. Ippolito May 2007 Half-life Calculations

10. Created by C. Ippolito May 2007 Transmutation an atom of one element turns into an atom of another element an atom of one element turns into an atom of another element TWO WAYS: TWO WAYS: radioactive decay radioactive decay particle bombardment particle bombardment transuranium elements transuranium elements all elements above 92 all elements above 92 synthesized by bombardment in reactors and particle accelerators synthesized by bombardment in reactors and particle accelerators

11. Created by C. Ippolito May 2007 Nuclear Fission Fission Fission neutron bombardment of isotopes splits nuclei into fragments neutron bombardment of isotopes splits nuclei into fragments energy released used to produce steam in power plants to run dynamos energy released used to produce steam in power plants to run dynamos Chain Reaction Chain Reaction neutron produced react with other atoms producing more neutrons neutron produced react with other atoms producing more neutrons Neutron Moderation Neutron Moderation slow down neutrons so reactor fuels can capture them to maintain chain reaction slow down neutrons so reactor fuels can capture them to maintain chain reaction Neutron Absorption Neutron Absorption decreases number of slow neutrons to slow down or stop reaction decreases number of slow neutrons to slow down or stop reaction “control rods” usually made of cadmium “control rods” usually made of cadmium

12. Created by C. Ippolito May 2007 Nuclear Fusion Fusion Fusion nuclei combine to produce a nucleus of greater mass nuclei combine to produce a nucleus of greater mass occurs in the sun occurs in the sun

13. Created by C. Ippolito May 2007 Detecting Radiation Geiger Counter Geiger Counter gas filled tube detects radiation ( α,β, γ) gas filled tube detects radiation ( α,β, γ) Scintillation Counter Scintillation Counter phosphor coated surface detects radiation ( α,β, γ) phosphor coated surface detects radiation ( α,β, γ) Film Badge Film Badge several layers of photographic film several layers of photographic film used to determine exposure of workers used to determine exposure of workers

14. Created by C. Ippolito May 2007 Radiation Usage Medical Diagnosis Medical Diagnosis radioisotope tracers follow metabolic paths radioisotope tracers follow metabolic paths Medical Treatment Medical Treatment destroy cancerous cells destroy cancerous cells Radioactive Dating Radioactive Dating determine age of fossils determine age of fossils