http://www.ck12.org Chapter 24. Nuclear Chemistry
FIGURE 24.8
The Fermi National Accelerator Labora-
tory in Illinois.Lesson Summary
- A half-life is the time it takes for half of a given sample of a radioactive nuclide to decay. Scientists use the
half-lives of some naturally occurring radioisotopes to estimate the age of various objects. - A decay series is a sequence of steps by which a radioactive nuclide decays to a stable nuclide.
- Artificial transmutation is used to produce other nuclides, including the transuranium elements.
Lesson Review Questions
Reviewing Concepts
- What fraction of a radioactive isotope remains after one half-life? Two half-lives? Five half-lives?
- When does a decay series end?
- What is the difference between natural radioactive decay and artificial transmutation?
- Why is an electric field unable to accelerate a neutron?
Problems
- The half-life of protactinium-234 is 6.69 hours. If a 0.812 mg sample of Pa-239 decays for 40.1 hours, what
mass of the isotope remains? - 2.86 g of a certain radioisotope decays to 0.358 g over a period of 22.8 minutes. What is the half-life of the
radioisotope? - Use the table above (Table24.4) to determine the time it takes for 100 mg of carbon-14 to decay to 6.25 mg.
- Fill in the blanks in the following radioactive decay series.
a.^23290 Th→α
β
→
β
→^22890 Th
b.^23592 U
α
→
β
→
α
→^22789 Ac
c. →α^23391 Pa
β
→ →α - Fill in the blanks in the following artificial transmutation reactions.