Half-Life

Front

What is the definition of half-life?

Back

The amount of time it takes for half the nuclei in a sample of the isotope to decay.

Front

What is the half-life of iodine-131?

Back

8 days.

Front

What is the half-life of carbon-14?

Back

5,730 years.

Front

Why is radioactive carbon-14 useful in determining the absolute age of geologic samples?

Back

Because radioactive isotopes decay at a regular rate.

Front

What happens to the amount of a radioactive isotope after one half-life?

Back

Half of the original amount will have decayed.

Front

How does the concept of half-life apply to radioactive decay?

Back

It describes the time required for half of the radioactive nuclei in a sample to decay.

Front

What is the half-life of a substance that decays to 25% of its original amount in 12 days?

Back

6 days.

Front

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

Back

1/8 of the original sample remains.

Front

What is the relationship between half-life and the stability of an isotope?

Back

Isotopes with longer half-lives are generally more stable than those with shorter half-lives.

Front

How can half-life be used in radiometric dating?

Back

It allows scientists to determine the age of materials by measuring the remaining amount of a radioactive isotope.