Radiometric Dating Worksheet w/ Answers
1. Define Geologic Time
Use of chemical analysis to estimate the age of geological specimens
2. What is radiometric dating?
A method of dating geological specimens by determining the proportions of particular radioactive isotopes present in a sample.
3. How are radioactive elements, like those on pg 195, used to date the rocks that
contain them?
See chart on page 195
4. What is the half-life of carbon-14?
5,700 years
5. What is the half-life of Uranium-lead dating (U-Pb)?
4.47 billion years
6. Can U-Pb be used to determine the age of a 40,000 year old tree? Explain your
answer.
No. Too Small or any other rationalization
7. Use what you know about half-lives and the chart below to answer the following
question: A sample contains 1,000 g of an isotope that has a half-life of 500 years.
How many half lives will have to pass before the sample contains less than 10 g
of the parent isotope?
# of Half Lives Amount of Parent Isotope (Grams)
0 1,000 g
1 500
2 250
3 125
4 62.5
5 31.25
6 15.625
7 7.8125
Use of chemical analysis to estimate the age of geological specimens
2. What is radiometric dating?
A method of dating geological specimens by determining the proportions of particular radioactive isotopes present in a sample.
3. How are radioactive elements, like those on pg 195, used to date the rocks that
contain them?
See chart on page 195
4. What is the half-life of carbon-14?
5,700 years
5. What is the half-life of Uranium-lead dating (U-Pb)?
4.47 billion years
6. Can U-Pb be used to determine the age of a 40,000 year old tree? Explain your
answer.
No. Too Small or any other rationalization
7. Use what you know about half-lives and the chart below to answer the following
question: A sample contains 1,000 g of an isotope that has a half-life of 500 years.
How many half lives will have to pass before the sample contains less than 10 g
of the parent isotope?
# of Half Lives Amount of Parent Isotope (Grams)
0 1,000 g
1 500
2 250
3 125
4 62.5
5 31.25
6 15.625
7 7.8125