section 3: nuclear reactions fission, the splitting of nuclei, and fusion, the combining of nuclei,...
TRANSCRIPT
SECTION 3: NUCLEAR REACTIONS
Fission, the splitting of nuclei, and fusion, the combining of nuclei, release tremendous amounts of energy.
KWhat I Know
WWhat I Want to Find Out
LWhat I Learned
• 12(C) Compare fission and fusion reactions.
• 12(B) Describe radioactive decay process in terms of balanced nuclear equations.
Nuclear ReactionsCopyright © 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 ReactionsCopyright © McGraw-Hill Education
Review
• mass number
Nuclear ReactionsCopyright © 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.
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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.
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Nuclear ReactionsCopyright © McGraw-Hill Education
INDUCED TRANSMUTATION REACTION EQUATIONS
Use with Example Problem 3.
Problem Write a balanced nuclear equation for the induced transmutation of oxygen-16 into nitrogen-13 by proton bombardment. An alpha particle is emitted from the nitrogen atom in the reaction.
ResponseANALYZE THE PROBLEMYou are given all of the particles involved in an induced transmutation reaction. Because the proton bombards the oxygen atom, they are reactants and must appear on the reactant side of the reaction arrow. KNOWN
reactants: oxygen-16 and a proton
products: nitrogen-13 and an α-particle
UNKNOWN
nuclear equation for the reactant = ?
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INDUCED TRANSMUTATION REACTION EQUATIONS
EVALUATE THE ANSWER
A proton has a charge of 1+ and a mass number of 1. Therefore, both charge and mass number are conserved. The formula for each participant in the reaction is also correct. The nuclear equation is written correctly.
SOLVE FOR THE UNKNOWN
• Use the periodic table to obtain the atomic number of oxygen.
Nuclear formula for oxygen-16: ()
• Use the periodic table to obtain the atomic number of nitrogen.
Nuclear formula for nitrogen-13: ()
Nuclear formula for proton: p
Nuclear formula for alpha particle: ()
• Write the balanced nuclear equation.
() + p → () + ()
Nuclear Reactions and Energy
• Mass and energy are related.
• Loss or gain in mass accompanies any reaction that produces or consumes energy.
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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.
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Nuclear Reactions and Energy
Nuclear binding energy is the amount of energy needed to break 1 mol of nuclei into individual nucleons.
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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.
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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.
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Chain Reactions
Animation
FPO
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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.
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Critical Mass
Animation
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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.
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Nuclear Reactors
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Nuclear Power Plants
Animation
FPO
Add link to Animation from page 881 here.
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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).
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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.
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Nuclear Fusion
Fusion reactions are also known as thermonuclear reactions.
Many problems must be solved before nuclear fusion is a practical energy source.
Nuclear ReactionsCopyright © McGraw-Hill Education
Nuclear ReactionsCopyright © 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