Nuclear Reactions

1
Nuclear Reactions

• What happens to some atoms
• Plasma chapter 9
• Roller Coaster chapter 24

2
Nuclear reactions

• What holds the Nucleus together?
• Like electrical charges push away from each
  other.
• Neutrons have no charge
• Strong Nuclear Force
• Will it hold any number of particles together?
• Hydrogen 1 - no neutrons - Stable
• Hydrogen 2 1 Neutron - Stable
• Hydrogen 3 2 Neutrons - Unstable

3
Nuclear reactions

• The Ratio of Neutrons to Protons determines
  Stability.
• Ratios for heavy nuclei between 11 and 32 are
  stable.
• Light nuclei like Hydrogen 3 are unstable as low
  as 21
• All nuclei over atomic 91 are unstable

4
Nuclear reactions

• What happens to an Unstable Atom?
• Radioactivity
• Nuclei give off particles
• Alpha 2 protons 2 neutrons Positive charge
• Beta - Electron Negative charge
• Gama High Energy Photon no charge
• Loss of an Alpha or a Beta particle changes the
  nature of the atom.

5
Nuclear reactions

• Alpha Particles
• Heavy, 2 Charge
• Large interaction with atoms while passing
  through matter. Can be stopped by a sheet of
  paper
• Beta Particles
• Light, 1- Charge, Faster than alpha particles
• Large interaction with atoms while passing
  through matter. Goes through paper but not
  aluminum foil.

6
Nuclear reactions

• Gama Rays
• No mass, no charge, speed of light
• Given off along with alpha and beta particles
• Little interaction, does damage by absorption,
  Takes a thick block of lead to stop them
• Radiation is detected using Geiger counter.

7
Nuclear reactions

• Fission atoms fall apart into two or more.
• Fusion Two light atoms combine to make one
• Uses for Radioactivity
• Destroying Cancer Cells
• Dating number of half lives
• C 14 (How long ago things have died)
• U (Age of Rocks)