1. Nuclear Chemistry I
The Nucleus II
III IV
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2. A. Mass Defect
Difference between the mass of an atom and the mass of its individual particles.
amu
amu
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3. B. Nuclear Binding Energy
Energy released when a nucleus is formed from nucleons.
High binding energy = stable nucleus.
E = mc2
E: energy (J)
m: mass defect (kg)
c: speed of light (3.00×108 m/s)
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4. B. Nuclear Binding Energy
Unstable nuclides are radioactive and undergo radioactive decay.
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5. II. Radioactive Decay I II
III IV
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6. A. Types of Radiation 2+ 1- 1+ Alpha particle () helium nucleus
paper 2+
Beta particle (-)
electron 1-
lead
Positron (+)
positron 1+
concrete
Gamma ()
high-energy photon
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7. B. Nuclear Decay Numbers must balance!! Alpha Emission parent nuclide
daughter
nuclide
alpha
particle
Numbers must balance!!
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8. B. Nuclear Decay Beta Emission electron Positron Emission positron
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9. B. Nuclear Decay Electron Capture electron Gamma Emission
Usually follows other types of decay.
Transmutation
One element becomes another.
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10. B. Nuclear Decay Why nuclides decay…
need stable ratio of neutrons to protons
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DECAY SERIES TRANSPARENCY

11. C. Half-life Half-life (t½)
Time required for half the atoms of a radioactive nuclide to decay.
Shorter half-life = less stable.
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12. C. Half-life mf: final mass mi: initial mass n: # of half-lives
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13. C. Half-life t½ = 5.0 s mf = mi (½)n mi = 25 g mf = (25 g)(0.5)12
Fluorine-21 has a half-life of 5.0 seconds. If you start with 25 g of fluorine-21, how many grams would remain after 60.0 s?
GIVEN:
t½ = 5.0 s
mi = 25 g
mf = ?
total time = 60.0 s
n = 60.0s ÷ 5.0s =12
WORK:
mf = mi (½)n
mf = (25 g)(0.5)12
mf = g
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