Radioactive Decay and Half-Lives

The video tutorial covers the topic of nuclear chemistry, focusing on radioactive isotopes and the concept of half-life. It explains the instability of radioactive isotopes and how they decay over time, emitting radiation. The tutorial introduces the concept of half-life as a measure of stability and provides examples of isotopes with varying half-lives, such as potassium-40 and sodium-24. A chalk analogy is used to help conceptualize half-life, and the tutorial includes problem-solving exercises involving isotopes like lead-194 and germanium-66.

What is a radioactive isotope?

• A form of energy

• A stable element that does not decay

• A type of chemical bond

• An unstable element that eventually decays

What does the graph of a radioactive isotope's decay show?

• The increase in material over time

• The constant amount of material

• The decrease in material over time

• The stability of the material

What is the half-life of an isotope?

• The time it takes for the isotope to double in quantity

• The time it takes for the isotope to become stable

• The time it takes for half of the atoms to decay

• The time it takes for all atoms to decay

Which isotope has a half-life of 1.3 billion years?

• Lead-194

• Germanium-66

• Sodium-24

• Potassium-40

In the chalk analogy, what happens after 15 minutes?

• The chalk becomes radioactive

• The chalk doubles in size

• Half of the chalk remains

• All the chalk is gone

After two half-lives, what fraction of the original material remains?

• 1/16

• 1/8

• 1/4

• 1/2

How much of Lead-194 remains after 44 minutes?

• 1/16

• 1/2

• 1/4

• 1/8

What is the half-life of Germanium-66?

• 1.3 billion years

• 15 hours

• 2.5 hours

• 11 minutes

If you start with 50 mg of Germanium-66, how much is left after 10 hours?

• 50 mg

• 25 mg

• 3.125 mg

• 0 mg

How many half-lives occur in 10 hours for Germanium-66?

• 2

• 3

• 4

• 5