Radioactivity

Question 1

What does it mean for decay to be random?

Answer 1

• Cannot know which nucleus will decay first
• Cannot know when a nucleus will decay
• Equal probability of each nucleus decaying
• Probability of decay in a certain time period can be known
• Probability of decay is constant

Question 2

Decay constant, λ

Answer 2

The proportion of nuclei decaying per unit time, or the probability of an individual nucleus decaying per unit time.

Question 3

Activity

Answer 3

Number of decays per second (measured in Becquerel, Bq)

Question 4

Half life

Answer 4

Time taken for half the nuclei initially present to decay OR time taken for the activity to decrease to half its initial value.