Half-Life

Front

What is half-life?

Back

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

Front

Where is the proton located in an atom?

Back

In the very dense nucleus.

Front

If you start with 50,000 atoms of uranium-238, how many will remain after one half-life (4.5 billion years)?

Back

25,000 atoms.

Front

What is the half-life of iodine-131?

Back

8 days.

Front

If 10 mg of iodine-131 is given to a patient, how much is left after 24 days?

Back

1.25 mg.

Front

What determines the type of element that an atom makes?

Back

The number of protons.

Front

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

Back

3 half-lives.

Front

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

Back

It decreases exponentially.

Front

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

Back

Isotopes with longer half-lives are generally more stable.

Front

How do you calculate the remaining quantity of a substance after multiple half-lives?

Back

Remaining quantity = Initial quantity / (2^n), where n is the number of half-lives.