3.64. Half-life and Radioactive Dating http://www.ck12.org
- Compare the decay rates of carbon-14 and uranium-238. How long does it take for 75 percent of a sample of
carbon-14 atoms to decay? How long does it take for 75 percent of a sample of uranium-238 to decay? Do
these rates depend on the number of atoms in the samples? - What percentage of carbon-14 remains in a sample after 10,000 years? How many years does it take for
uranium-238 to decay to this same percentage? - Why would you not use carbon-14 to measure the age of the rock?
Review
- What is radioactive dating?
- Which radioisotope in theTable3.15 could you use to date a fossil thought to be about 500 million years old?
Explain your choice. - Why does the amount of carbon-14 in an organism remain the same throughout the organism’s life? Why does
the amount change after the organism dies?