Integrated Science 2 Name Per s1

Origins #___ Measuring Age with Radioactive Decay Integrated Science 2 Name Per Radioactive dating is a very important tool in determining the age of fossils and rocks. In this activity, you will construct and use data tables and graphs that illustrate the decay of various radioactive elements.

1. Uranium 238 (Half-life= 4.5 billion years)

Time (billions Percent of of years) Original Material Unchanged (%)

4.5 50

a) Complete the table above. Construct a graph of the data. Remember your rules of graphing. Use your graph to answer the questions below. b) You find a rock that has 12.5% of its Uranium 238 remaining unchanged. What is the approximate age? (Hint: use your graph.)

c) You find a rock that has 35% of its Uranium 238 remaining unchanged. What is the approximate age?

d) Would Uranium-238 be useful in dating something 10,000 years old? Explain.

2. Carbon-14 (Half-life= 5,568 years)

Percent of Time (years) Original Material Unchanged (%)

a) Complete the table above and construct a graph of the data. Remember your rules of graphing. Use your graph to answer the questions below. b) You find a skeleton with about 65% of its original carbon-14 remaining unchanged. How old is the skeleton?

c) Would Carbon-14 be useful in dating something 10,000 years old? Explain.

3. Strontium-90 (Half-life= 28 years). Complete the table below:

Time (years) Percent of Original Material Unchanged (%)