April 21, Wednesday

Discussion questions
Apr 21
Lab Handout
Define each of the variables in this equation.
P:
P­0:
l:
t:
Zimmer 2010, Radioactive clocks
1. What is the different between 12C, 13C and 14C? Which is the most unstable? What is the half-life of 14C?
Carbon-12 is stable and carbon-13 are stable, in which they are easier for organisms to absorb, and this can be seen in old sedimentary rocks (class lecture). Carbon-14, however, is unstable; it decays fast (class lecture).
2. What are some other radiometric decay systems (besides carbon-14) that are useful for determining the ages of events in Earth’s history?
According to Zimmer, the radioactive isotopes, strontium and rubidium, are some ways to measure the age of rocks. Once lava hardens, for example, the strontium levels within the rock remain and no more can enter. The different levels of each isotope can then be measured by calculating its radioactive elements.
3. Why don’t stable elements have half-lives?
4. Write a short dialogue between you and a 12-year old friend explaining Figure 3.1
5. How do we calculate the absolute of fossils?