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Lecture 15

CHE 110 Lecture Notes - Lecture 15: Control Rod, Nuclear Fission, Critical Mass


Department
Chemistry
Course Code
CHE 110
Professor
Sarah Boesdorfer
Lecture
15

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Wednesday, November 16, 2016
Nuclear Chemistry
Review
-How many electrons, protons, and neutrons in each of the following?
Carbon-14 [E: 6 P: 6 N: 8]
235/92 U [E: 92 P: 92 N: 143]
4/2 He 2+ [E: 0 P: 2 N: 2]
-What part of an atom determines what element it is?
How many protons
-True or False: The mass number for an isotope can be found on the Periodic Table.
Terminology
-Radiation: Transmission of energy
-Ionizing Radiation: High enough energy can cause atoms to ionize
Can knock electron off atom
Free radicals: Things with unpaired electrons (ions) very reactive
-Radioactive or Radioactivity: Spontaneous emission of radiation and/or particle
from an unstable nucleus (Neutrons : Protons ratio too high/low)
Emitted forms of radiation from radioactive decay
-Alpha (a) particles- stopped by any material
"Cannon Balls"- want to do damage (high speed)
He Nucleus [4/2]He 2+
-Beta (B) particles
"Bullets"
Neutron converted to a proton or reverse
B- = [0/-1]e electron - High Energy
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Wednesday, November 16, 2016
B+ = [0/1]e positive electron (positron) - less common
Positrons
-Gamma (y) rays- get through anything but lead
"Lasers"
Typically, but not always, with an Alpha or Beta Decay
No mass, no charge, just high Energy
-All are ionizing
Question
-Radon and Uranium are both alpha emitters (they produce alpha particles during their
radioactive decay process). Why are we concerned about Rn seeping from our
subsoil, but not the U ore that is there as well?
Radon is a gas so it cannot be contained as easily as Uranium. The gas can get
inside of you (lungs). More common in winter.
Writing Balanced Nuclear Equations
-Nuclear Reactions DO NOT = Chemical Reactions
Not worries about charge/type - just # subatomic particles total
-[222/86] Rn --> __[218/84] Po__ + [4/2] He 2+
Radioactive Decay Series
-Everything breaks into something new radioactive
-Eventually a stable isotope is hit
Decay and Half-Life
-Half-Life is the time required for the quantity to fall to half of its initial value
-C-14 (Carbon) dating
-Problems:
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