Science 8
Unit 3
Matter
LAB – Radioactive Decay
Objective: In this lab you will learn about radio isotopic dating. You will be keeping track of the
change in redium disks (redium atoms) to goldium disks (goldium atoms) over time. You will
gather data for 6 trial times and graph your results. You will determine how old your bone is by
measuring the half-life of your redium at various stages of decay. After graphing your results you
will analyze your data.
Purpose: To date the age of bones using radio isotopic decay.
Materials: 32 redium/goldium squares, bone outline, data table, and graphs, pencil
Procedure:
1. Place the 32 squares inside your bone, pink side up (each pink square represents an
atom of redium.
2. Record ‘32’ redium atoms on your Data Table under Redium Remaining on the
Living Animal row and ‘0’ under Goldium Remaining.
3. Your animal just died; redium is no longer being made in the bones. Over time
redium decays into goldium. Now randomly flip over half of the redium atoms
turning them into goldium. Fill in the number of redium atoms (16) and the number of
goldium atoms (16) in your Data Table in Time Trial 1.
4. More time passes. Half the remaining redium decays into goldium. Turn over half the
remaining redium atoms and enter the new data into your Data Table in Time Trial 2.
5. Continue to flip over half the remaining redium atoms through Time Trials 3-6 and
enter your data in the Data Table in the appropriate Time Trial row.
6. Plot the numbers for the amounts of Redium Remaining (y-axis) and Goldium
Remaining (x-axis) on a graph. (Start with 32 atoms of redium and 0 atoms of
goldium.) Be sure to label the axes with titles and numbers.
7. Complete the Analysis part of the Data Table. Begin with the Living Animal row.
Since the animal is alive no half-lives have passed. Place a ‘0’ in the Number of
Half-Lives box. Since the animal is still alive, the bones are ‘0’ years old. Place a ‘0’
in the Age in Years box.
8. Complete the Analysis part of the Data Table for Time Trials 1-6. In Time Trial 1,
since half the original redium is left, one half-life has passed. Enter ‘1’ under
Number of Half-Lives and ‘20,000’ under Age in Years. Continue to complete the
Data Table.
9. Plot the data for Redium Remaining (y-axis) and Age in Years (x-axis, count by
10,000) on a second graph. Be sure to label the axes with titles and numbers.
Data: See attached Data Table and Graphs.
Science 8
Unit 3
Matter
Name: ______________________________
Date: ______________ Period: __________
LAB – Radioactive Decay
Data table for Radioactive Decay
DATA
Living Animal
Time Trial 1
Time Trial 2
Time Trial 3
Time Trial 4
Time Trial 5
Time Trial 6
Redium
Remaining
32
Goldium
Remaining
0
ANALYSIS
Number of
Age
Half-Lives
in Years
0
0
Redium Decay into Goldium
Redium Remaining vs. Age in Years