Carbon-14 Dating Lab
Scientists use Carbon-14 dating to determine the absolute age of
a fossil. Carbon-14 breaks down to form Nitrogen-14 over time.
Carbon-14’s half-life is 5,730 years. This means that every 5,730
years half of the carbon-14 has decayed and become nitrogen-14.
Scientists can analyze the ratio of parent (carbon-14) to
daughter (nitrogen-14) isotopes and determine the age of a onceliving object. This technique of absolute dating can only be used
if the fossil is younger than 70,000 years old. In this lab, you will
model the radioactive decay of atoms within a fossil.
Procedure
1. Count out 64 white beans. These beans represent a bone of an organism
that has just died. The white beans model carbon 14. This is the parent
isotope.
2. Remove half the white beans and replace them with red beans. The red
beans represent Nitrogen 14. Red beans are the daughter isotope. This
models the ratio of a fossil that is 5,730 years old.
3. Write the half-life age in the chart.
4. Continue replacing half the white beans with red beans until only one white
bean remains. Each time, fill in the chart.
5. Answer the reflection questions after you have completed the chart.
Half-life
0
1
2
3
4
5
6
# white beans
Carbon-14
64
# red beans
Nitrogen-14
0
Age of “bone”
0
5,730
Reflection Questions:
1. Would you be able to use this methodology to determine the age of a rock?
Why or why not?
2. Would you be able to use this methodology to determine the age of a fossil
200,000 years old? Why or why not?
3. How could you design another lab to demonstrate or model this same
concept?