Decay and Half-life

Front

What is decay in the context of radioactive substances?

Back

Decay refers to the process by which an unstable atomic nucleus loses energy by emitting radiation, resulting in the transformation of the element into a different element or isotope.

Front

What is half-life?

Back

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

Front

How do you calculate the remaining amount of a substance after a certain number of half-lives?

Back

Remaining amount = Initial amount × (1/2)^(number of half-lives).

Front

If a substance has a half-life of 8 days, how much of a 40 mg sample remains after 16 days?

Back

10 mg.

Front

What happens to the mass of a radioactive substance after each half-life?

Back

The mass of the substance is halved after each half-life.

Front

If you start with 80 g of a substance with a half-life of 2 minutes, how much will remain after 6 minutes?

Back

10 g.

Front

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

Back

Isotopes with shorter half-lives are generally less stable and decay more quickly than those with longer half-lives.

Front

How many half-lives does it take for a substance to decay from 100 g to 12.5 g if its half-life is 2 minutes?

Back

3 half-lives.

Front

What is the formula to determine the number of half-lives that have passed?

Back

Number of half-lives = Total time elapsed / Half-life duration.

Front

If a sample of Carbon-14 has a half-life of 5730 years, how long will it take to decay from 8 g to 1 g?

Back

11,460 years.