Chapter 6.4 - 'Half-Life And Decay Series'

Question 1

State the equation for finding the number of nuclei remaining after a certain amount of half-lives.

Answer 1

N=N0(1/2)^n

N is the number of radioactive nuclei remaining
N0 is the initial number of radioactive nuclei
n is the number of half-lives elapsed

Question 2

State the equation for finding the number of half lives in a period of time.

Answer 2

n=T/t1/2

n is the number of half lives elapsed.
T is the period of time that the radioactive nuclei is destroyed.
t1/2 is the half life period of the radioactive nuclei.

Question 3

What is the chance of an atom decaying in each half life.

Answer 3

50%

Question 4

State what ‘activity’ measures and how it’s measured.

Answer 4

Disintegrations per second

Measured in becquerels, Bq

Question 5

State the equation for activity.

Answer 5

A=A0(1/2)^n

A is the activity of the radioactive nuclei remaining.
A0 is the initial activity of the radioactive nuclei.
n is the number of half lives elapsed.

Question 6

Define ‘decay series’.

Answer 6

A series of decay where a radioactive element is decomposed into different elements continuously until it produces a stable atom.

Question 7

Explain what the ‘half-life’ of a radioisotope is.

Answer 7

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