What is Radioactivity?

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What is Radioactivity?
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Radioactivity is.....

• The disintegration of the nucleus of an isotope
  (form of an element) is called radioactivity.
• Isotopes with unstable nuclei, or radioisotopes,
  degrade or disintegrate into different isotopes
  with release of subatomic particles or energy.
• Ionizing radiation is high energy radiation and
  can be damaging.

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What are isotopes ?
deuterium
tritium
protium
These atoms are isotopes of hydrogen. They all
have one proton and one electron, but different
numbers of neutrons.
B. Hudson, 2001
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An Example of Radioactivity
e-
p
n
p
3H
3He
An unstable nucleus, like tritium will eject an
energetic electron (beta particle) and transform
into an atom of helium-3 ( 3He )
B. Hudson, 2001
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What are common types of ionizing radiation?

• Alpha
• Fast moving
• Positively charged 4He2
• Beta
• High energy negative charge
• High speed electron emission
• Gamma
• High energy
• Electromagnetic radiation

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What is a half-life?

• The time it takes for an unstable isotope to
  degrade to another isotope.
• This usually means that you have a completely
  different element!

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GO TO STUDENT BEAN ACTIVITY AND COME BACK TO LAST
SLIDES LATER
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So... does this mean that radioactivity is
forever?

• If a rabbit jumps halfway to his hole each time
  will he ever get in?
• Actually, at some point our fuzzy friend will
  just fall in the hole no matter what you
  hypothesize!

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The same is true for radioactive elements.....

• After 10 half-lives, an element is considered to
  be completely degraded!

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So........

• How long will carbon-14 with a half-life of
  around 5000 years be hanging around?
• (how old can something be for carbon dating to
  work?)