1. Aim: What are the two types of Nuclear Reactions? Do Now: 1. Get into your groups and compare your answers to your homework.

2. Nuclear Energy In nuclear reaction, mass is converted into energy; there is no conservation of mass. Two types of nuclear reactions Fission Fusion

3. Nuclear Fission Occurs when one atom absorbs a neutron and splits into two or more pieces, giving off tremendous amount of energy. In a fission reaction, the sum of the masses of the pieces formed is less than the mass of the original heavier piece, because some mass is converted into energy.

5. Fission of Uranium When U-235 goes through fission, it releases 3 neutrons. Those neutrons bombard other U-235 causing a chain reaction. The atomic bomb is an uncontrolled chain reaction. A fission chain reaction can be controlled in a nuclear reactor, used in some power plants to make electricity.

6. Nuclear Reactor In a nuclear power plant, heat is created in the nuclear reactor through nuclear fission. The heat is then used to turn water into steam which is used to drive the generators to produce electricity

7. Nuclear Fusion Nuclear fusion is the joining (or fusing) of the nuclei of two atoms to form a single heavier atom. At extremely high temperatures and high pressure, the nuclei (positively charged) can readily combine to form heavier elements and in the process release considerable energy. This reaction occurs on the sun.

8. Nuclear Fusion The mass of the nucleus formed after fusion is less than the sum of the mass of the two substances fused, because some mass is converted to energy. The energy generated in a fusion reaction is greater than the energy generation in a fission reaction.

9. Nuclear Fusion of Nuclei of Isotopes of Hydrogen Deuterium TritiumHelium Neutron

10. Fission Fusion Reactions produce energy. Mass is converted into energy Nucleus splits Nuclei unite- gives much more energy than fission.

11. Radioactive Isotopes Benefits 1.Tracers 2.Medical: radioactive iodine can be used to diagnose and treat thyroid. 3.Food can be stored longer. 4.Nuclear Power 5.Radioactive dating 1.U-238 and Pb-206 are used for geological dating. 2.C-14 used for dating living material. Risks 1. Biological Damage: damage or destroy cells 2. Long Term Storage 3. Accidents: nuclear explosion 4. Pollution: nuclear waste

12. 1. In a fusion reaction, reacting nuclei must collide. Collisions between two nuclei are difficult to achieve because the nuclei are A. both negatively charged and repel each other B. both positively charged and repel each other C. oppositely charged and attract each other D. oppositely charged and repel each other 2. Given the fusion reaction: 2 1 H + 2 1 H  X + energy Which particle is represented by X? A. 1 1 H B. 3 2 He C. 3 1 H D. 4 2 He 3. Which change takes place in a nuclear fusion reaction? A. Matter is converted to energy. B. Energy is converted to matter. C. Ionic bonds are converted to covalent bonds. D. Covalent bonds are converted to ionic bonds. 4. Nuclear fusion differs from nuclear fission because nuclear fusion reactions A. form heavier isotopes from lighter isotopes B. form lighter isotopes from heavier isotopes C. convert mass to energy D. convert ener gy to mass 5. A nuclear fission reaction and a nuclear fusion reaction are similar because both reactions A. form heavy nuclides from light nuclides B. form light nuclides from heavy nuclides C. release a large amount of energy D. absorb a large amount of energy 6. In which reaction is mass converted to energy by the process of fission? A. 14 7 N + 1 0 n  14 6 C + 1 1 H B. 235 92 U + 1 0 n  87 35 Br + 146 57 La + 3 1 0 n C. 226 88 Ra  222 86 Ra + 4 2 He D. 2 1 H + 2 1 H  4 2 He 7. Which statement explains why nuclear waste materials may pose a problem? A.They frequently have short half-lives and remain radioactive for brief periods of time. B. They frequently have short half-lives and remain radioactive for extended periods of time. C. They frequently have long half-lives and remain radioactive for brief periods of time. D. They frequently have long half-lives and remain radioactive for an extended period of time