1. A. Nuclear Forces Do nuclei contain attractive or repulsive forces?
repulsion
attraction

2. + + A. Nuclear Forces Strong Nuclear Force (SNF)
binds protons and neutrons together in the nucleus.
stronger than electric repulsive force over very short distances. + +

3. A. Nuclear Forces Effect of Size on Stability Small Nucleus
SNF is relativity static
more protons, more electric repulsion
larger, more unstable (↑ 82 protons)
Small Nucleus
Large Nucleus
attraction
repulsion
attraction
repulsion

4. B. Nuclear Reactions Transmutation +
change of an atom of one element (atom) to an atom of different element
identity changes by changing # of PROTONS (At #)
nuclear reactions can change nuclei and proton # (Atomic #) to make different atoms
chemical reactions transfer or share electrons to rearrange atoms +

5. E = mc2 B. Nuclear Reactions Nuclear Binding Energy 3.00 x 108 m/s!!!
the energy released when a nucleus is formed during fusion or when nuclei are formed during fission.
little mass converted to LOTS of energy
E = mc2
3.00 x 108 m/s!!!

6. Nuclear Fission of Uranium-235
B. Fission
splitting a larger nucleus into smaller (daughter) nuclei and/or particles. (Nuclear Power Plants use this)
Nuclear Fission of Uranium-235

7. An aside definition:
A radionuclide (radioactive nuclide, radioisotope or radioactive isotope) is an atom that has excess nuclear energy, making it unstable. This excess energy will normally be emitted from the nucleus as radiation.

8. Nuclear Fission of Uranium-235
B. Fission
Nuclear Fission of Uranium-235

9. A fission chain reaction is a sequence of reactions where a reactive product or by-product causes additional reactions to take place. In a chain reaction, positive feedback leads to a self-amplifying chain of events.
Positive feedback is usually generated by neutron production and moderation.
A neutron moderator is a medium that reduces the speed of neutrons so they can be used in a nuclear reaction involving uranium-235 or a similar fissile nuclide.
A neutron absorber is a medium that removes neutrons from the chain reaction process

10. B. Fission Storage of Radioactive Waste
spent fuel rods in water pools (short term) or dry casks of concrete/steel (long term).

11. C. Fusion combining of 2 nuclei to form 1 larger nucleus
is the “typical” product
much more energy
powers stars naturally
high temp plasma

12. Tokamak Fusion Test Reactor
C. Fusion
Fusion reactors (not sustainable, very hard to keep going)
Tokamak Fusion Test Reactor

13. C. Fission vs Fusion Fission Fusion vs. FISSION FUSION 235U is limited
meltdown risk
radioactive waste
less energy
Hydrogen is abundant
no meltdown risk
harmless product
not yet sustainable

14. Coming up:
Writing Nuclear Reactions
Nuclear Decay Rate Calculations

15. Quick Quiz.
E=mc2 shows how a little bit of _________ can be converted into lots of __________.
energy, mass.
mass, energy.
mass, light.
light, energy. 15

16. Quick Quiz. Which statement about nuclear reactions is FALSE?
Heat and light in the sun are produced by hydrogen fusion reactions.
The total mass of the products is slightly less than the total mass of the reactants.
In fusion, nuclei are combined, and in fission, nuclei are split.
Power plants use fusion of H isotopes. 16