4.3 over Absolute Age

Front

What is half-life?

Back

Half-life is the time required for half of the radioactive atoms in a sample to decay.

Front

What is the half-life of a radioactive element that decays to 25% of its original amount after 100 years?

Back

The half-life is 50 years.

Front

What is potassium-argon dating?

Back

Potassium-argon dating is a method used to date rocks and minerals using the radioactive decay of potassium-40 to argon-40.

Front

If a radioactive isotope has a half-life of 10 years, how much of the original sample remains after 30 years?

Back

After 30 years, 1/8 of the original sample remains.

Front

What does it mean if a sample contains 1/4 of its original radioactive isotope?

Back

It means that two half-lives have passed since the original amount was present.

Front

How do you calculate the age of a sample using half-life?

Back

The age of a sample can be calculated by determining how many half-lives have passed and multiplying that by the half-life duration.

Front

What is radiocarbon dating?

Back

Radiocarbon dating is a method for determining the age of an object containing organic material by measuring the amount of carbon-14 it contains.

Front

If a radioactive element has a half-life of 5 days, how long will it take for a sample to decay to 1/16 of its original amount?

Back

It will take 20 days.

Front

What is uranium-lead dating?

Back

Uranium-lead dating is a method used to date geological samples by measuring the decay of uranium isotopes into lead isotopes.

Front

What happens to the amount of a radioactive isotope over time?

Back

The amount of a radioactive isotope decreases exponentially over time as it decays.