RADIOACTIVE AND STRATIGRAPHIC DATING SCIENCE 101 SPRING 1999

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1. What are the three most common type of radiation?  What is the difference in each type of radioactive decay (i.e., what particles are emitted)?  Which types of radioactive decay result in the formation of an element that differs from the parent element?
2. What types of radiation are most dangerous to humans?  Why?
3. Why do some elements undergo radioactive decay and others do not?
4. Based on your knowledge of alpha and beta particles, determine the identity of the isotope formed in each decay.
• ²³⁸U --> alpha -particle +
• ¹⁴C --> beta-particle +
• ²¹⁸Po --> alpha-particle +
5. ¹³¹I is used to treat thyroid diseases.  Its half life is about 8 days.  If we start with 10 g today, how much ¹³¹I will remain in 32 days?
6. Why does an ancient cotton cloth contain less ¹⁴C than a piece of cotton made last year?  Wear did the "lost" carbon "go"?
7. Why isn't ¹⁴C dating useful in the following situations?
• determining the age of a metal artifact?
• determining whether a piece of cotton was made last year or three years ago
8. What are the laws of stratigraphy?  How do these laws help determine relative ages of strata?
9. How do the laws of stratigraphy help with the interpretation of radioactive dating of materials in various strata?