Half-Life

Front

What is Half-Life?

Back

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

Front

How is the remaining amount of a substance calculated after multiple half-lives?

Back

After each half-life, the remaining amount of the substance is halved. For example, after 1 half-life, 1/2 remains; after 2 half-lives, 1/4 remains; after 3 half-lives, 1/8 remains.

Front

If 1/4 of a radioactive substance remains, how many half-lives have passed?

Back

2 half-lives have passed.

Front

What is the half-life of iodine-131?

Back

The half-life of iodine-131 is 8 days.

Front

Why do some elements have half-lives?

Back

Some elements have half-lives because they radioactively decay.

Front

After the third half-life, how much of the sample is left?

Back

1/8 of the sample is left.

Front

What is the half-life of carbon-14?

Back

The half-life of carbon-14 is approximately 5,730 years.

Front

What happens to the activity of a radioactive substance over time?

Back

The activity decreases over time as the substance decays.

Front

What is a radioactive isotope?

Back

A radioactive isotope is an atom with an unstable nucleus that decays over time, emitting radiation.

Front

How can half-life be used in dating archaeological finds?

Back

Half-life can be used in carbon dating to determine the age of organic materials by measuring the remaining carbon-14.