Fission, the splitting of nuclei, and fusion, the combining of nuclei, release tremendous amounts of energy. Section 3: Nuclear Reactions K What I Know W What I Want to Find Out L What I Learned

12(C) Compare fission and fusion reactions. 12(B) Describe radioactive decay process in terms of balanced nuclear equations. Nuclear Reactions Copyright © McGraw-Hill Education

Essential Questions How are mass and energy related? How do nuclear fission and nuclear fusion compare and contrast? What is the process by which nuclear reactors generate electricity? Nuclear Reactions Copyright © McGraw-Hill Education

Review mass number Nuclear Reactions Copyright © McGraw-Hill Education Vocabulary New induced transmutation transuranium element mass defect nuclear fission critical mass breeder reactor nuclear fusion thermonuclear reaction

Induced Transmutation The process of striking nuclei with high-velocity charged particles is called induced transmutation. One element can be converted into another by spontaneous emission of radiation. Elements can also be forced to transmutate by bombarding them with high-energy alpha, beta, or gamma radiation. Nuclear Reactions Copyright © McGraw-Hill Education

Induced Transmutation Transuranium elements are the elements with atomic numbers 93 and higher, immediately following uranium. Particle accelerators use electrostatic and magnetic fields to accelerate charged particles to very high speed. Nuclear Reactions Copyright © McGraw-Hill Education

Nuclear Reactions and Energy Mass and energy are related. Loss or gain in mass accompanies any reaction that produces or consumes energy. Nuclear Reactions Copyright © McGraw-Hill Education

Nuclear Reactions and Energy The difference between a nucleus and its component nucleons is called the mass defect. Most chemical reactions produce or consume so little energy that the accompanying changes in mass are negligible. Energy released from nuclear reactions have significant mass changes. The mass of a nucleus is always less than the sum of the masses of the individual protons and neutrons that comprise it. Binding together or breaking an atom’s nucleons involves energy changes. Nuclear Reactions Copyright © McGraw-Hill Education

Nuclear Reactions and Energy Nuclear binding energy is the amount of energy needed to break 1 mol of nuclei into individual nucleons. Nuclear Reactions Copyright © McGraw-Hill Education

Nuclear Fission The splitting of nuclei into fragments is known as nuclear fission. Fission is accompanied with a very large release of energy. Nuclear power plants use fission to produce electricity by striking uranium-235 with neutrons. Nuclear Reactions Copyright © McGraw-Hill Education

Nuclear Fission Each fission of U-235 releases two additional neutrons. Each of those neutrons can release two more neutrons. The self-sustaining process is called a chain reaction. Nuclear Reactions Copyright © McGraw-Hill Education

Nuclear Fission Samples with enough mass to sustain a chain reaction are said to have critical mass. Without sufficient mass, neutrons escape from the sample before starting a chain reaction. Nuclear Reactions Copyright © McGraw-Hill Education

Nuclear Reactors Nuclear fission produces the energy generated by nuclear reactors. The fission within a reactor is started by a neutron-emitting source and is stopped by positioning the control rods to absorb virtually all of the neutrons produced in the reaction. The reactor core contains a reflector that reflects neutrons back into the core, where they react with fuel rods. Nuclear reactors produce highly radioactive nuclear waste. Breeder reactors produce more fuel than they consume. Nuclear Reactions Copyright © McGraw-Hill Education

Nuclear Reactors Nuclear Reactions Copyright © McGraw-Hill Education

Nuclear Fusion The combining of atomic nuclei is called nuclear fusion. Nuclear fusion is capable of releasing very large amounts of energy. It is possible to bind together two or more lighter elements (mass number less than 60). Nuclear Reactions Copyright © McGraw-Hill Education

Nuclear Fusion Fusion has several advantages over fission. Lightweight isotopes are abundant. Fusion products are not radioactive. However, fusion requires extremely high energies to initiate and sustain a reaction. Nuclear Reactions Copyright © McGraw-Hill Education

Nuclear Fusion Fusion reactions are also known as thermonuclear reactions. Many problems must be solved before nuclear fusion is a practical energy source. Nuclear Reactions Copyright © McGraw-Hill Education

Nuclear Reactions Copyright © McGraw-Hill Education Review Essential Questions How are mass and energy related? How do nuclear fission and nuclear fusion compare and contrast? What is the process by which nuclear reactors generate electricity? Vocabulary induced transmutation transuranium element nuclear fusion thermonuclear reaction mass defect nuclear fission critical mass breeder reactor