Nuclear Physics/Chemistry

Front

What is the most effective material for stopping gamma rays?

Back

Several centimeters of lead.

Front

What is the half-life of technetium-99?

Back

6.0 hours.

Front

If 100.0 mg of technetium-99 is injected, how much remains after 18 hours?

Back

12.5 mg.

Front

What type of nuclear reaction involves the emission of an electron?

Back

Beta decay.

Front

What type of nuclear reaction involves the emission of a helium nucleus?

Back

Alpha decay.

Front

What type of nuclear reaction involves the release of energy without a change in mass number?

Back

Gamma decay.

Front

What is the half-life of gold-198?

Back

2.69 days.

Front

If a sample of gold-198 has a mass of 10.0 g, how much remains after 10.76 days?

Back

0.625 g.

Front

What is the formula to calculate remaining mass after a certain number of half-lives?

Back

Remaining mass = Initial mass × (1/2)^(time elapsed / half-life).

Front

Define half-life in nuclear chemistry.

Back

The time required for half of the radioactive nuclei in a sample to decay.