GEOL3650: Energy: A Geological Perspective
Nuclear Power: New Green Energy or Lasting Mistake
Nuclear Power
Activity 2: Nuclide Chart, Radioactivity and Nuclear Reactions
The nuclide chart plots proton number or atomic number (Z) on the vertical axis and
neutron number (N) on the horizontal axis (see diagram below). A band of stable nuclides is
formed by the 254 naturally occurring stable isotopes. Another approximately 50 isotopes
have half-lifes long enough to occur naturally on Earth. No elements with atomic number
(Z) greater than 82 are stable. All of these decay by alpha particle emission. Isotopes above
the stable band have too many protons and decay by electron capture and positron
emission. Below the band, isotopes have too few protons and decay by beta emission. For
nuclear power, alpha and beta decay are the most important types of decay mechanisms
and hence radiation.
Uranium-238 (238U) is a naturally-occurring radioactive isotope that decays to lead-206
(206Pb) with a half-life of 4.47x109 yr. The entire decay series is shown on a portion of
the nuclide chart below. Use this diagram to help you write the nuclear reactions
discussed below.
10-Feb-16
Nuclide Chart, Radioactivity and Nuclear Reactions
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GEOL3650: Energy: A Geological Perspective
Nuclear Power: New Green Energy or Lasting Mistake
1. The first step in the decay series is from
describing this step.
U to
238
234Th
. Derive the nuclear reaction
Th  24n  
238
92
234
90
U 
alpha decay
2. When the decay series reaches polonium-218 (218Po), there is a branch in the decay
series. Write the two possible decay reactions at this point in the series.
218
84
214
82
Po 
Pb
alpha decay
218
84
218
85
Po 
At 
0
1
 
beta decay
3. At the end of the decay series mercury-206 (206Hg) decays to
reaction for this transformation.
206
80
Hg 
Pb. Write the
206
Tl+ 10  
206
81
beta decay
206
81
Tl 
206
82
Pb+
0
1
 
beta decay
10-Feb-16
Nuclide Chart, Radioactivity and Nuclear Reactions
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