Half-life

Front

What is Half-life?

Back

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

Front

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

Back

It is reduced to half of its original amount.

Front

If the half-life of a substance is 10 years, how much of a 20 g sample remains after 20 years?

Back

5 g.

Front

What is the half-life of strontium-90?

Back

25 years.

Front

How much strontium-90 will remain after 100 years if the initial amount is 4.0 g?

Back

0.25 g.

Front

What type of decay releases energy?

Back

Radioactive decay.

Front

If the half-life of uranium-232 is 70 years, how many half-lives are needed to reduce 10 g to 1.25 g?

Back

3 half-lives.

Front

What is alpha decay?

Back

A type of radioactive decay where an atomic nucleus emits an alpha particle.

Front

What is beta decay?

Back

A type of radioactive decay where a beta particle (electron or positron) is emitted.

Front

What is the formula to calculate the remaining amount of a substance after n half-lives?

Back

Remaining amount = Initial amount × (1/2)^n.