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Hemingway
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7.3 Nuclear Reactions
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Nuclear fission and fusion are processes that involve extremely large amounts of __________
o ___________ = the splitting of a large nucleus into two smaller nuclei, subatomic
particles and energy
o __________ = the joining of nuclei
Fission
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Large nuclei tend to be ___________ due to repulsive forces between ___________
To increase stability atoms may split into ___________ atoms with lighter nuclei
This is accompanied by a large _______________________
Can be used to generate power
However nuclear reactors produce radioactive ______________
As well ________________ are a concern
Review of Chemical Reactions
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A + B  AB , the mass of the reactants is equal to the mass of the reactants
# of ____________=_____________ #= atoms _____________
Chemical reactions = change in ___________arrangement
Change in energy is relatively _____
Nuclear Reaction
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Reactions involving a change in an______________
Process in which an atoms nucleus ____________ by gaining or releasing
_____________________
Can be 1, 2 or all 3 types of ______________________ (protons, neutrons, electrons) as well as
gamma rays.
In a nuclear reaction the _________change in________ results in a _______ change in ________
o Ex- Nuclear fission of 1 gram of pure Uranium-235
o Releases the same amount of energy as burning 2 tonnes of coal.
Nuclear Equations for Induced Nuclear Reactions
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____________________________________ consists of the release of
o alpha, beta and gamma radiation.
It is possible to __________ a nucleus to become __________
Nuclear reaction occurs immediately
o Can be induced by _______________________ with alpha particles, beta particles or
gamma rays
This reaction is similar to other types of decay, but the difference is that the particles are part of
the ______________
Hemingway
Name:
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N-14 bombarded by alpha particle, turns into f-18 which quickly decays into O-17 and a proton.
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The rules for writing these equations are the same as earlier nuclear equations
o ________________ must equal on both sides of the equation
o __________(represented by atomic #’s)must equal on both sides of the equation
Sub atomic Particle symbols
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Reading Check pg 315 all
Nuclear Fission
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Nuclear energy used to produce power or nuclear weapons comes from _______________
Nuclear fission is the _____________of one heavy nucleus into two or more smaller nuclei,
some sub-atomic particles, and energy.
A heavy nucleus is usually unstable, due to many positive protons pushing apart.
When fission occurs:
 ___________________________
 ___________________________
Nuclear Fission of Uranium-235
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It is much easier to crash a ________________ than a _______________ into a nucleus to
release energy.
Most nuclear fission reactors and weapons use this principle.
A neutron, , crashes into an atom of stable _____________ to create unstable ____________
which then undergoes radioactive decay.
After several steps, atoms of ____________and _____________are formed, along with the
release of ______________ and huge quantities of _________________
Hemingway
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Name:
Practice Problems pg 317All
Chain Reactions
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Once the nuclear fission reaction has started, it can keep going.
The ___________released in the induced reaction can then trigger more reactions on other
uranium-235 atoms.
This chain reaction can quickly ___________________
Fermi realized that materials that could absorb some neutrons could help to control the chain
reaction.
Materials like cadmium __________________ to limit reaction
Nuclear reactors have complex systems to ensure the chain reaction stays at ______________
An uncontrolled chain reaction can result in a ___________________________.
Nuclear bombs are created using this concept.
Nuclear power plants can generate large amounts of electricity.
 Ontario, Quebec and New Brunswick currently generate nuclear power.
 Canadian-made nuclear reactors are called ____________reactors.
 CANDU reactors are considered safe and effective and are sold throughout the world.
CANDU Reactors and Hazardous Wastes
 Canada’s nuclear research into the safe use of nuclear reactions has resulted in the creation of
CANDU reactors. (Canadian deuterium uranium reactor)
 The reactors are known to be safe and easy to shut down in an emergency.
 ____________is an __________ of _____________which has one proton and one neutron
( Hydrogen-2)
 Reactors produce ________________ which turns electricity-generating turbines.
______________ wastes produced by nuclear reactions are problematic.
 Some waste products, like fuel rods can be re-used.
 Some products are very radioactive, however, and must be stored ______________________
 Most of this waste is ______________ or stored in ___________
 It will take _____________(thousands of years) before the material is safe.
Nuclear Fusion
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Nuclear fusion = _______________________ into one heavier nucleus.
In the core of the Sun, ______________ nuclei join
o under tremendous heat and pressure to form a _______________
When the helium atom is formed, huge amounts of ________ is released.
It is this energy that passes from the sun as radiation bringing ______________ to earth
Hemingway
Fusion on Earth?
 Scientists cannot yet find a safe, manageable
o method to harness the energy of nuclear fusion.
 So-called “cold fusion” would occur at
o temperatures and pressures that could be ___________
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Homework
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