Radioactive Decay & Half-life Midterm Review

Front

What is radioactive decay?

Back

Radioactive decay is 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 a half-life?

Back

A half-life is the time required for half of the radioactive atoms in a sample to decay into a different element or isotope.

Front

What type of particle is emitted when Uranium-238 decays?

Back

An alpha particle.

Front

If the half-life of a substance is 2.4 minutes, how much of a 6.25 g sample remains after 9.6 minutes?

Back

1.56 g.

Front

What is the formula to calculate the initial mass (M_i) needed based on half-life?

Back

M_i = M_f * (2^(t/T_half)), where M_f is the final mass, t is the time elapsed, and T_half is the half-life.

Front

What is the decay product of Plutonium-240 when it emits an alpha particle?

Back

Uranium-236.

Front

How do you calculate the remaining mass after a certain time given the half-life?

Back

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

Front

What is the half-life of Selenium-83?

Back

25 minutes.

Front

How much of a 20 mg sample of Selenium-83 remains after 100 minutes?

Back

1.25 mg.

Front

If a sample of Barium-122 has a half-life of 2 minutes, how much was initially present if 15.0 g remains after 10 minutes?

Back

480 g.