Half-Life

Front

What is half-life?

Back

Half-life is the time required for half of the quantity of a radioactive isotope to decay into a different element or isotope.

Front

How do you calculate the remaining percentage of a parent isotope after a certain number of half-lives?

Back

The remaining percentage can be calculated using the formula: Remaining % = (1/2)^n * 100%, where n is the number of half-lives.

Front

If the half-life of an isotope is known, how can you determine the number of half-lives that have passed?

Back

You can determine the number of half-lives that have passed by comparing the initial amount of the isotope to the remaining amount and using the formula: n = log(final amount/initial amount) / log(1/2).

Front

What is the remaining amount of a substance after 3 half-lives if you start with 80 g?

Back

After 3 half-lives, the remaining amount would be 80 g * (1/2)^3 = 10 g.

Front

What is the half-life of uranium-232?

Back

The half-life of uranium-232 is 70 years.

Front

What is alpha decay?

Back

Alpha decay is a type of radioactive decay in which an atomic nucleus emits an alpha particle (2 protons and 2 neutrons), resulting in a new element.

Front

How much of a 10 mg sample of iodine-131 remains after 24 days if its half-life is 8 days?

Back

After 24 days, which is 3 half-lives (24/8), the remaining amount is 10 mg * (1/2)^3 = 1.25 mg.

Front

What is the formula to calculate the remaining mass of a radioactive substance after a certain time?

Back

The formula is: Remaining mass = Initial mass * (1/2)^(time elapsed / half-life).

Front

What happens to the percentage of the parent isotope as more half-lives pass?

Back

As more half-lives pass, the percentage of the parent isotope decreases exponentially.

Front

What is the significance of knowing the half-life of a radioactive isotope?

Back

Knowing the half-life helps in predicting how long it will take for a certain amount of the isotope to decay, which is crucial in fields like medicine, archaeology, and nuclear energy.