Assignment:
Radioactive Decay
Carbon-14 is a radioactive Isotope of Carbon-12. How many protons and neutrons are in the nucleus of C-12? __________ In C-14 ___________ While an organism is alive, the ratio of Carbon-14 to Carbon-12 is in equilibrium. This does not mean that there are equal amounts of C-14 and C-12, but rather, their proportion (ratio) to each other is constant. However, when the organism dies, no more C-12 is absorbed and the C-14 begins to decay. This decay changes the ratio. We know that C-14 is a beta emitter, so it will decay into ______________?
Question 1. Draw a graph (in Excel) depicting C-14 decay as follows:
- Start with 100% C-14. 0%N.
- Show amounts (in percent) of C-14 for four (4) half lives.
- Show corresponding amounts of Nitrogen for each of those points.
Question 2. If this organism were found to have died 11,400 years ago, what would be the ratio of Carbon: Nitrogen?
Question 3. If this organism has a 3:1 ratio of N:C-14, how long ago might this organism have died?
Question 4. Do you see a pattern here similar to any others in this activity? Explain.
Question 5. Why do we keep referring to when the organism "died" rather than "how old" in analyzing C-14 decay?