Atoms and Nuclear Radiation

Question 1

Why do unstable nuclei give out radiation?

Answer 1

• Unstable nuclei undergo decay to become more stable

- As they release radiation, they become more stable

Question 2

What is radioactive decay?

Answer 2

When an unstable nucleus gives out radiation in order to become more stable

Question 3

Define ‘activity’ in an unstable nucleus

Answer 3

Activity is the rate of decay at a source of unstable nuclei

Question 4

What is the unit of radioactive decay?

Answer 4

Becquerels (bq)

Question 5

What is count rate?

Answer 5

• Count rate is the number of radioactive decays per second

- From a radioactive source

Question 6

Example of a detector that may be used to measure count rate?

Answer 6

Geiger-Muller tube

Question 7

Four types of nuclear radiation :

Answer 7

1. Alpha particles
2. Beta particles
3. Gamma rays
4. Neutrons

Question 8

What does an alpha particle consist of?

Answer 8

• Two protons
• Two neutrons
• SAME AS THE HELIUM NUCLEUS

Question 9

Range of alpha particle through hair?

Answer 9

A few centimerers (2-10)

Question 10

What stops beta radiation from passing through a point?

Answer 10

• A thin sheet of aluminium

- Or several metres of air

Question 11

What will stop gamma radiation from passing through a point?

Answer 11

• Several centimetres of lead

- Or a few metres of concrete

Question 12

Which type of radiation is most ionising?

Answer 12

Alpha radiation

Question 13

Which type of radiation is least ionising?

Answer 13

Gamma radiation

Question 14

What changes when a gamma ray is radiated?

Answer 14

• No change to charge

- No change to mass

Question 15

What is the nature of radioactive decay life?

Answer 15

• RANDOM

- Impossible to predict which nuclei will decay and when

Question 16

What is the half life of a radioactive isotope?

Answer 16

The time that it takes for the count rate of a radioactive substance to half from its original level

Question 17

What is radioactive contamination?

Answer 17

The presence of unwanted radioactive nuclei on other materials

Question 18

What is irridation?

Answer 18

• Exposing a material to nuclear radiation
• That does NOT become radioactive
• Can kill living cells

Question 19

What is peer review?

Answer 19

• When studies are published and shared with other scientists
• To allow findings to be individually checked
• For flaws or errors

Question 20

How can radiation be used?

Answer 20

In smoke detectors

Question 21

How do smoke detectors work?

Answer 21

• Alpha emitter emits alpha particles
• However is blocked as the smoke passes through
• So the sensor detects change
• Sounds the alarm

Question 22

How can irritation be used?

Answer 22

• Sterilising surgical equipment

- Food can be irradiated to kill any unwanted microbes

Question 23

What is contamination in terms of radiation?

Answer 23

When a source becomes unwantedly radioactive and emits radiation