Topic 6 - Radioactivity - Decay Process

Question 1

What is Beta-Minus Decay?

Answer 1

A neutron becomes a proton and releases an electron

Question 2

What occurs during Beta-Plus Decay?

Answer 2

A proton becomes a neutron and releases a positron

Question 3

What is the general formula for decay processes?

Answer 3

AX → ZY + decay particle

Question 4

What is an alpha particle equivalent to?

Answer 4

A helium nucleus

Question 5

What is the formula for alpha decay?

Answer 5

AX → 4-27+20

Question 6

What is a beta particle?

Answer 6

An electron emitted from the nucleus

Question 7

What is the formula for beta decay?

Answer 7

AX → Z+1Y+-le (+Ve)

Question 8

What is a gamma ray?

Answer 8

Electromagnetic radiation

Question 9

What happens to nuclei after decay regarding energy?

Answer 9

They often have excess energy, released as gamma radiation

Question 10

What does activity refer to in radioactive decay?

Answer 10

The number of decays in a sample per second

Question 11

How does activity change over time?

Answer 11

It decreases exponentially

Question 12

What are the units of activity?

Answer 12

Becquerel, Bq

Question 13

What is a half-life?

Answer 13

The time taken for half the nuclei in a sample to decay

Question 14

How can half-life be defined in terms of activity?

Answer 14

The time taken for the activity of a sample to decay by half

Question 15

Can the decay of an individual nucleus be predicted?

Answer 15

No, it cannot be predicted

Question 16

What does the half-life constant allow us to predict?

Answer 16

The activity of a very large number of nuclei during decay

Question 17

How is net decline calculated after X half-lives?

Answer 17

Net decline = initial number - number after X half-lives

Question 18

If there were initially 80 nuclei with a half-life of 15 minutes, what would be the net decline after 3 half-lives?

Answer 18

Net decline = 80 - 10 = 70