Chapter 24

What property of isotopes allows radiotracers to be useful in studying chemical reactions?

Which unit of radiation dose, rem or rad, is most useful for describing the effect of radiation on living tissue?

PET scans In PET scans, the radiotracer emits positrons, which travel a few millimeters before interacting with electrons. How can the original radiotracer be detected?

Figure 24.34 shows the position of two workers near a radioactive gamma source. The worker at Position A is standing 2.5 \(\mathrm{m}\) from the source and receives an exposure of 0.98 mrem \(/ \mathrm{s} \cdot \mathrm{m}^{2} .\) The worker at Position \(\mathrm{B}\) receives an exposure of 0.50 \(\mathrm{mrem} / \mathrm{s} \cdot \mathrm{m}^{2} .\) What is the distance of the worker at Position \(\mathrm{B}\) from the source?

Technetium-104 has a half-life of 18.0 min. How much of a 165.0 g sample remains after 90.0 minutes have passed?

The half-life of plutonium-239 is \(24,000\) y. How much nuclear waste generated today will remain in 1000 years?

Red blood cells A medical researcher is using a chromium-51 source to study red blood cells. The gamma-emission intensity at a distance of 1.0 \(\mathrm{m}\) is 0.75 \(\mathrm{mrem} / \mathrm{s} * \mathrm{m}^{2}\) . At what distance would the intensity drop to 0.15 mrem \(/\) \(\mathrm{s} \cdot \mathrm{m}^{2}\) ?

The binding energy per nucleon reaches a maximum around what mass number? Explain how this number is related to the fission and fusion processes.

You have an alpha source, a beta source, and a gamma source. Design a plan to use a Geiger counter, paper, and foil to determine the identity of each source.

What is the half-life of radon-222 if a sample initially contains 150 \(\mathrm{mg}\) and only 18.7 \(\mathrm{mg}\) after 11.4 days?

Make and Use Graphs Thorium-2 31 decays to lead- 207 by emitting the following particles in successive steps: \(\beta, \alpha, \alpha, \beta, \alpha, \alpha, \alpha, \beta, \beta, \alpha .\) Plot each step of the decay series on a graph of mass number versus atomic number. Label each plotted point with the symbol of the radioisotope.

Apply Chemical treatment is often used to destroy harmful chemicals. For example, bases neutralize acids. Why can't chemical treatment be applied to destroy the fission products produced in a nuclear reactor?

Compare A biological concern about working around some radioactive materials is the radioactive dust a person might inhale. Compare the effect of alpha radiation outside the body and inside the body.

Interpret Small radioactive sources are often used for laboratory experiments. The radioactive substance is enclosed in a metal container with a small window. A gamma source might be covered with a stainless steel window. What would you expect the window of an alpha source to be like? Why?

Analyze Some radioisotopes used for medical imaging have half-lives as short as several hours. Why is a short half-life beneficial? Why is it a problem?

Infer The production of electricity at nuclear fission reactor facilities is controversial. Think about the benefits and dangers of this technology. Explain your opinion about whether nuclear reactors should be used.

Identify each property as chemical or physical. (Chapter 3) a. The element mercury has a high density. b. Solid carbon dioxide sublimes at room temperature. c. Zinc oxidizes when exposed to air. d. Sucrose is a white crystalline solid.

Why does the second period of the periodic table contain eight elements? (Chapter 6\()\)

Draw each molecule and show the locations of hydrogen bonds between the molecules. (Chapter 8\()\) a. two water molecules. b. two ammonia molecules c. one water molecule and one ammonia molecule

What process takes place in each situation? (Chapter 12\()\) a. a solid air-freshener cube getting smaller and smaller b. dewdrops forming on leaves in the morning c. steam rising from a hot spring d. a crust of ice forming on top of a pond

If the volume of a sample of chlorine gas is 4.5 \(\mathrm{L}\) at 0.65 atm and \(321 \mathrm{K},\) what volume will the gas occupy at STP? (Chapter 13\()\)

Explain what a buffer is and why buffers are found in body fluids. (Chapter 18)

Explain how the structure of benzene can be used to explain its unusually high stability compared to other unsaturated cyclic hydrocarbons. (Chapter 21\()\)

Marie Curie and Irene Curie Joliot Research and report on the lives of Marie Curie and her daughter, Irene Curie Joliot. What kind of scientific training did each receive? What was it like to be a female chemist in their time? What discoveries did each make?