Nuclear Chemistry

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Nuclear Reactions

• result in a change in the atoms nucleus.
• Example
• Ra ? Rn a

226 88
222 86
42
4
226 88
42
222 86
Rn

• Ra ? a

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238 92
42
234 90

• U ? a

Th
6
14 6
0-1
14 7

• C ? ß

N
7
9236
141 56
235 92
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• U n? Ba Th ?

10
3 n
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Problem

• Write the equation for I undergoing beta
  decay.

131 53
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Problems
223 88
42

• Ra ? ? a
• a N ? ? H
• Rb ? ? ?

11
42
14 7
8738
8737
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Problems
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• H ? ? He
• C ? ? ß

42
14 6
0-1
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Write a balanced nuclear equation for the alpha
decay of the following radioisotope
234 92
U
12
230 90
4 2
U ? Th ?
234 92
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Write the symbols for the followingneutron alp
haproton beta(electron) gammapositron
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neutron proton electronpositronalphabetaga
mma

• n
• p
• e e
• ?? ??

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11
00
0-1
01
42
0-1
00
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Half-Life (t1/2)

• time required for half of the atoms in a sample
  to decay.

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Radioactive Decay Rates
The percent of a stontium-90 sample remaining
over a period of four half-lives.
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Determining Decay

• fraction of a radioisotope remaining after n
  half-lives is (½)n
• mfinal minitial (½)n

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Problem

• N-13 has a half-life of 10 minutes. How much of
  2.00 g. N-13 will exist after 3 half-lives?
• How long is 3 half-lives?

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Problem

• Thorium-234 has a half-life of 25 days. How much
  of the original will remain after 50 days?