Radioactive decay

Question 1

What happens to the nuclei of a particle when an alpha or beta particle is released? How does this lead to decay?

Answer 1

• becomes an isotope of a different element
  
  • proton number changes
• the number of nuclei of the initial radioactive isotope therefore decreases

Question 2

How does the rate of decay of an isotope change?

Answer 2

• rate decreases
• decays exponentially

Question 3

What is the half-life of a radioactive isotope?

Answer 3

• T_1/2
• Time taken for the mass of the isotope to decrease to half the initial mass

Question 4

What is the activity of a radioactive isotope?

Answer 4

• A
• the number of nuclei of the isotope that disintegrate per second
• rate of change of the number of nuclei

Question 5

What are the units for activity? What do they mean?

Answer 5

• the becquerel (Bq)
• where 1 Bq = 1 disintegration per second

Question 6

What is the activity of a radioactive isotope proportional to?

Answer 6

• its mass
• as mass decreases, activity decreases

Question 7

How can the energy transfer per second from a radioactive source be measured?

Answer 7

• energy transfer per second = AE
  
  • A = activity
  • E = energy of each particle