Radioactive Decay

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Radioactive Decay
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Radioactive materials decay from the Parent
material into the Daughter Product.
Daughter Product
Original Parent Material
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• Some atoms in the parent are isotopes
• These atoms have a different number of neutrons
  than protons
• They are unstable
• As isotopes decay to stable daughter energy is
  released

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Youll never know which atoms will decay...
(16 atoms)
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or when ...
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But one thing we do know...
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...is that it always takes the same amount of
time for half to disappear.
(8 atoms)
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Radioactive Decay

• Parent unstable
• Daughter stable
• Half-life is the time required for HALF of the
  atoms of the unstable parent to decay to stable
  daughter

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Radioactive Decay Data
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Each half-life, the amount of atoms gets cut in
half.
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Since you dont know how many atoms you started
with, a ratio between parent to daughter will
tell you how many half-lives have gone by.
100 parent 0 daughter 0 half lives
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One half-life.
50 parent 50 daughter 1 half-life
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Two half-lives.
25 parent 75 daughter 2 half-lives
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Three half-lives.
12.5 parent 87.5 daughter 3 half-lives
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Four half-lives.
6.25 parent 93.75 daughter 4 half-lives
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Dont worry about the last atom. You start with
so many trillions that you never really get
there. (It will just decay and then theyre
all gone.)
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Shape of curve similar for each radioactive
isotope
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Half Life

• Continues indefinitely
• Random and spontaneous
• Not affected by temperature or pressure
• Not affected by mass or volume of parent