Unit 11: Nuclear Physics

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a strong nuclear force
Protons and neutrons are held together by what?
Atomic number -z-
# of protons; defines each element
-n-
# of neutrons; can vary for each element
Mass number -A-
Total number of protons -z- and neutrons -n-
Isotope
the term used to describe different atoms of the same element
SAME; DIFFERENT
Isotopes of the same element have the _______________ number of protons, but a ________________ number of neutrons.
Example: Carbon- 14
Element name- Mass number -A-
Undergo radioactive decay in order to reduce their Potential Energy
What happens to unstable isotopes?
14 C ; (14 mass # – 6 protons = 8 neutrons)
6
Mass # Element symbol
Atomic #
Alpha decay (least dangerous)
Heavy atom emits Helium nucleus (2 pro, 2 neu) in order to reduce potential energy; LEAST DANGEROUS- requires a sheet of paper to block
Beta decay
Beta minus: add a proton, and emit a neutron

Beta plus (reverse beta decay): emit a proton, and add a neutron

Gamma decay
nucleus is in an excited state and emits high energy light in order to reduce potential energy; MOST DANGEROUS- requires layers of lead to block
Measuring decay rates
(1/2)^ # of half lives
Half-life
the time it takes for roughly half of the atoms to decay
Fusion
2 or more atoms *combine* and Energy is released in the process; requires HIGH temps.
Fission
a heavy atom is *split* into 2 or more atoms; 1 fission reaction causes exactly 1 other fission reaction
Fuel
*4 Components in a Nuclear PP:* what undergoes the Fission; Uranium, plutonium, thorium
Coolant
*4 Components in a Nuclear PP:* transfers heat from the reaction to keep fuel cool; water/ lead-Bismoth
Moderators
*4 Components in a Nuclear PP:* Slow neutrons to help regulate the reaction; carbon, graphite, water
Control rods
*4 Components in a Nuclear PP:* Absorb neutrons to help regulate the reactions; silver, cobalt, Boron, Indium
Chicago Pile 1941
1st sustained Nuclear reaction; SCRAM
Safety, Control, Rod, Axe, Man
Categories: Atomic Physics