35.7
half-lives of radioactive elements
radioactive element element's half-life (billion years) element it decays into
lutetium-176
halfnium-176
potassium-40
11.93
argon-40
rhenium-187
423
osmium-187
rubidium-87
48.8
strontium-87
thorium-232
lead-208
uranium-238
lead-206
graph it on a separate sheet of paper, draw a bar graph showing the half-lives of the radioactive elements in the chart.
be sure to label your graph's x- and y-axes, and give your graph a title
analyze it
1. which element has the longest half-life? the shortest?
4. can radiocarbon dating be used to date most rocks?
explain why or why not.
2. which radioactive element is the source for lead-208?
5. suppose scientists used radioactive dating to determine
that rocks at a dig site were 3 million years old. what would
this data suggest about the age of any fossils found at the
site? explain your answer.
3. how many elements in the chart have a half-life of less
han 15 billion years?