Chapter 42: Q 5 Conceptual Questions (page 1235)
Are the following decays possible? If not, why not?
Short Answer
Therefore, the decays are explained.
Chapter 42: Q 5 Conceptual Questions (page 1235)
Are the following decays possible? If not, why not?
Therefore, the decays are explained.
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Get started for free| The element gallium has two stable isotopes: 69 Ga with an atomic mass of 68.92 u and 71 Ga with an atomic mass of 70.92 u. A periodic table shows that the chemical atomic mass of gallium is 69.72 u. What is the percent abundance of 69 Ga?
Alpha decay occurs when an alpha particle tunnels through the Coulomb barrier. FIGURE CP42.63 shows a simple one-dimensional model of the potential-energy well of an alpha particle in a nucleus with A ≈ 235. The 15 fm width of this one-dimensional potential-energy well is the diameter of the nucleus. Further, to keep the model simple, the Coulomb barrier has been modeled as a 20-fm-wide, 30-MeV-high rectangular potential-energy barrier. The goal of this problem is to calculate the half-life of an alpha particle in the energy level E = 5.0 MeV. a. What is the kinetic energy of the alpha particle while inside the nucleus? What is its kinetic energy after it escapes from the nucleus? b. Consider the alpha particle within the nucleus to be a point particle bouncing back and forth with the kinetic energy you found in part a. What is the particle’s collision rate, the number of times per second it collides with a wall of the potential? c. What is the tunneling probability Ptunnel ?
Calculate (in ) the binding energy per nucleon for and . Which is more tightly bound?
A 115 mCi radioactive tracer is made in a nuclear reactor. When it is delivered to a hospital 16 hours later its activity is 95 mCi. The lowest usable level of activity is 10 mCi.
a. What is the tracer’s half-life?
b. For how long after delivery is the sample usable?
The fact that A cancels means that all nuclei have this density. It is a staggeringly large density, roughly 1014 times larger than the density of familiar liquids and solids. One early objection to Rutherford’s model of a nuclear atom was that matter simply couldn’t have a density this high. Although we have no direct experience with such matter, nuclear matter really is this dense .
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