1. Chapter 25 Nuclear Chemistry 25.4 Radiation in Your Life
25.1 Nuclear Radiation
25.2 Nuclear Transformations
25.3 Fission and Fusion
25.4 Radiation in Your Life
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2. How does a smoke detector work?
CHEMISTRY & YOU
How does a smoke detector work?
A typical household smoke detector contains a small amount of americium, Am, in the form of AmO2. Americium-241 is a radioisotope.
241 95
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3. What are three devices used to detect radiation?
Detecting Radiation
Detecting Radiation
What are three devices used to detect radiation?
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4. Detecting Radiation
Radiation emitted by radioisotopes has enough energy to knock electrons off some atoms of a bombarded substance, producing ions.
The radiation emitted by radioisotopes is called ionizing radiation.
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5. Detecting Radiation
It is not possible for humans to see, hear, smell, or feel ionizing radiation.
People must rely on detection devices to alert them to the presence of radiation and to monitor its level.
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6. Detecting Radiation
It is not possible for humans to see, hear, smell, or feel ionizing radiation.
People must rely on detection devices to alert them to the presence of radiation and to monitor its level.
These devices work because of the effects of the radiation when it strikes atoms or molecules in the detector.
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7. Radiation can expose a photographic plate.
Detecting Radiation
Radiation can expose a photographic plate.
When the plate is developed, its darkened areas show where the plate has been exposed to radiation.
X-rays allow doctors to see inside the body without having to cut into the body. Color was added to highlight parts of the image.
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8. CHEMISTRY & YOU
Radiation emitted in a smoke detector ionizes the nitrogen and oxygen in the air, and a current flows. When smoke particles attach to the ions, the ions lose their charge. What happens next?
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9. CHEMISTRY & YOU
Radiation emitted in a smoke detector ionizes the nitrogen and oxygen in the air, and a current flows. When smoke particles attach to the ions, the ions lose their charge. What happens next?
Once the ions in the air inside the smoke detector lose their charge, the current decreases. An electronic circuit detects the drop in current, which causes an alarm to sound.
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10. Detecting Radiation
Geiger counters, scintillation counters, and film badges are commonly used to detect radiation.
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11. A Geiger counter uses a gas-filled metal tube to detect radiation.
Detecting Radiation
Geiger Counter
A Geiger counter uses a gas-filled metal tube to detect radiation.
When ionizing radiation penetrates a thin window at the end of the tube, the gas inside the tube becomes ionized.
Each time a Geiger tube is exposed to radiation, current flows.
The bursts of current drive electronic counters or cause audible clicks from a built-in speaker.
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12. Geiger counters can detect alpha, beta, and gamma radiation.
Detecting Radiation
Geiger Counter
Geiger counters can detect alpha, beta, and gamma radiation.
Astronomers use Geiger counters to detect cosmic rays from outer space.
Geologists use Geiger counters to search for radioactive minerals.
This person is using a Geiger counter to check for radiation in contaminated dirt at a spill site.
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13. Scintillation Counter
Detecting Radiation
Scintillation Counter
A scintillation counter uses a phosphor-coated surface to detect radiation.
When ionizing radiation strikes the surface, the phosphor produces bright flashes of light, or scintillations.
The number of flashes and energies are detected electronically.
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14. Scintillation Counter
Detecting Radiation
Scintillation Counter
Scintillation counters are more sensitive than Geiger counters.
They can detect some radiation that would not be detected by a Geiger counter.
Scintillation counters are used to track the path of radioisotopes through the body.
They are also used to monitor the possible transport of radioactive materials across national borders and through airports.
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15. This is a diagram of a typical film badge.
Detecting Radiation
Film Badge
This is a diagram of a typical film badge.
The badge contains layers of photographic film covered with black light-proof paper.
To reach the film,
radiation must pass through a filter, which absorbs some radiation, or a transparent area through which radiation can pass easily.
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16. Detecting Radiation
Film Badge
People who work with or near ionizing radiation must wear a film badge to monitor their exposure while they are at work.
At specific intervals, the film is removed and developed.
The strength and type of radiation exposure are determined by comparing the darkness of the film in all the exposed areas.
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17. B. scintillation counter C. film badge
Which of the following detectors would you use to locate uranium ores in a soil sample?
A. Geiger counter
B. scintillation counter
C. film badge
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18. B. scintillation counter C. film badge
Which of the following detectors would you use to locate uranium ores in a soil sample?
A. Geiger counter
B. scintillation counter
C. film badge
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19. What are some practical uses of radioisotopes?
Using Radiation
Using Radiation
What are some practical uses of radioisotopes?
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20. What are some practical uses of radioisotopes?
Using Radiation
Using Radiation
What are some practical uses of radioisotopes?
Although radiation can be harmful, it can be used safely and has many important applications.
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21. Using Radiation
Radioisotopes are used to analyze matter, study plant growth, diagnose medical problems, and treat diseases.
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22. Using Radiation
Analyzing Matter
Scientists use radiation to detect trace amounts of elements in samples.
This process is called neutron activation analysis.
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23. Using Radiation
Analyzing Matter
A sample is bombarded with neutrons from a radioactive source.
Some atoms in the sample become radioactive.
The half-life and type of radiation emitted can be detected and analyzed by a computer.
Because this data is unique for each isotope, scientists can determine what radioisotopes were produced and infer what elements were in the original sample.
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24. Museums use this process to detect art forgeries.
Using Radiation
Analyzing Matter
Museums use this process to detect art forgeries.
Crime laboratories use it to analyze gunpowder residue.
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25. Using Radiation
Using Tracers
Radioisotopes called tracers are used in agriculture to test the effects of herbicides, pesticides, and fertilizers on plants.
A tracer is introduced into the substance being tested.
Next, plants are treated with the tagged substance.
Devices that detect radioactivity are used to locate the substance in the plants.
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26. Using Radiation
Using Tracers
The tracer may also be monitored in animals that consume the plants, as well as in water and soil.
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27. Diagnosing Medical Problems
Using Radiation
Diagnosing Medical Problems
Radioisotopes can be used to detect disorders of the thyroid gland, which is located in the throat.
To diagnose thyroid disease, the patient is given a drink containing a small amount of the radioisotope iodine-131.
After about two hours, the amount of iodide uptake is measured by scanning the patient’s throat with a radiation detector.
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28. Diagnosing Medical Problems
Using Radiation
Diagnosing Medical Problems
The radioisotope technetium-99m is used to detect brain tumors and liver disorders.
Phosphorus-32 is used to detect skin cancer.
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29. Radiation is one method used in the treatment of some cancers.
Using Radiation
Treating Diseases
Radiation is one method used in the treatment of some cancers.
Cancer is a disease in which abnormal cells in the body are produced at a rate far beyond the rate for normal cells.
The mass of cancer cells that result from this runaway growth is called a tumor.
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30. Using Radiation
Treating Diseases
Fast-growing cancer cells are more susceptible to damage by high-energy radiation such as gamma rays than are healthy cells.
Radiation can be used to kill the cancer cells in a tumor.
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31. Using Radiation
Treating Diseases
Some normal cells are also killed, however, and cancer cells at the center of the tumor may be resistant to the radiation.
The benefits of the treatment and the risks to the patient must be carefully evaluated before radiation treatment begins.
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32. Using Radiation
Treating Diseases
Some normal cells are also killed, however, and cancer cells at the center of the tumor may be resistant to the radiation.
The benefits of the treatment and the risks to the patient must be carefully evaluated before radiation treatment begins.
Cobalt-60 and cesium-137 are typical radiation sources for cancer therapy.
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33. Using Radiation
Treating Diseases
Salts of radioisotopes can also be sealed in gold tubes and directly inserted in tumors.
This method of treatment is called seeding.
The salts emit beta and gamma rays that kill the surrounding cancer cells.
Because the radioisotope is in a sealed container, it is prevented from traveling to other parts of the body.
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34. Using Radiation
Treating Diseases
Prescribed drugs containing radioisotopes of gold, iodine, or phosphorus are sometimes used in radiation therapy.
A dose of iodine-131 larger than that used to detect thyroid diseases can be given to a patient to treat the disease.
The iodine that collects in the gland emits beta particles and gamma rays, which provide therapy.
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35. Describe the benefits and risks of radiation therapy for cancer.
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36. Describe the benefits and risks of radiation therapy for cancer.
Radiation therapy can kill cancer cells at a higher rate than healthy cells, so it can be used to destroy fast-growing tumors. However, it also damages healthy cells, and cells in the center of the tumor may not be reached by the radiation.
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37. Key Concepts
Geiger counters, scintillation counters, and film badges are commonly used to detect radiation.
Radioisotopes are used to analyze the composition of matter, study plant growth, diagnose medical problems, and treat diseases.
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38. Glossary Terms
ionizing radiation: radiation with enough energy to knock electrons off some atoms of a bombarded substance to produce ions
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39. Electrons and the Structure of Atoms
BIG IDEA
Electrons and the Structure of Atoms
The ability to detect particles emitted when nuclei decay helps scientists study processes that take place in living organisms.
This ability also allows scientists to determine the age of fossils and other objects.
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40. END OF 25.4
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