Extend your thinking: The slow decay of radioactive materials can be used to find the age of rocks, fossils, and
archaeological artifacts. In a process called radiometric
dating, scientists measure the proportions of radioactive
atoms and daughter atoms in an object to determine its
age. Carbon-14 is a useful isotope because it is found in
wood, ash, bone, and any other organic materials.
You can use the Half-life Gizmo to model the decay of
Carbon-14, which has a half-life of approximately 6,000
years (actual value is 5,730 years). In the Gizmo, select
User chooses half-life and Theoretical decay. Set the
Half-life to 6 seconds (to represent 6,000 years) and the
Number of atoms to 100.
Use the Gizmo to estimate the age of each of the objects
below. For these questions, each second in the Gizmo
represents 1,000 years.
Description
Age (years)
Egyptian papyrus with 63% of its original carbon-14 atoms
Aboriginal charcoal with 22% of its original carbon-14 atoms.
Mayan headdress with 79% of its original carbon-14 atoms
Neanderthal skull with 3% of its original carbon-14 atoms
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