P4

Question 1

Radioactive Decay

Answer 1

Some atomic nuclei are unstable. The nucleus gives out radiation
as it changes to become more stable

Question 2

What is the activity?

Answer 2

Activity is the rate at which a source of unstable nuclei decays

Question 3

What is activity measured in?

Answer 3

Becquerel (Bq)

Question 4

What is the Count - Rate?

Answer 4

The number of decays recorded each second by a
detector (eg Geiger-Muller tube)

Question 5

How can nuclear radiation be emitted?

Answer 5

• Alpha Particle
• Beta Particle
• Gamma Ray

Question 6

What does an Alpha Particle consist of?

Answer 6

Consists of two neutrons and two protons, it is the same as a helium nucleus

Question 7

What does a Beta Particle consist of?

Answer 7

Electron

Question 8

What is a Gamma Ray?

Answer 8

Electromagnetic radiation

Question 9

What is the air range of a Beta Particle?

Answer 9

1 metre

Question 10

What is the air range of a Gamma Ray?

Answer 10

Hundreds of metres

Question 11

What is the air range of an Alpha Particle?

Answer 11

8 centimetres

Question 12

What is an Alpha particle stopped by?

Answer 12

Skin or Paper

Question 13

What is a Gamma-ray stopped by?

Answer 13

Thick Lead

Question 14

What is a Beta particle stopped by?

Answer 14

Thin Aluminium

Question 15

How many atoms can 1 Alpha Particle Ionise?

Answer 15

10,000; it has a high charge, cant travel far

Question 16

How many atoms can 1 Gamma Ray Ionise?

Answer 16

1; has no charge, can travel far

Question 17

How many atoms can 1 Beta Particle Ionise?

Answer 17

100; small charge, can travel little distance

Question 18

If there are too many neutrons, what radiation would we use?

Answer 18

Beta Particles; neutron splits into a proton and neutron, the electron is emitted (beta), which will carry a lot of energy

Question 19

Ionisation

Answer 19

Radiation removes electrons from atoms, turning them into ions

Question 20

What is the most dangerous Particle to ingest?

Answer 20

Alpha
- Ionising
- Can’t leave the body (least penetrating)

Question 21

What can radiation be used for?

Answer 21

• Sterilising medical equipment (gamma)
• Irradiation (gamma)
• Medical Tracers (Beta/Gamma)
• Smoke Detector (Alpha)
• Measure paper Thickness (Beta)

Question 22

What is the most accurate way to measure the speed of Decay?

Answer 22

Half Life

Question 23

What is Half-Life?

Answer 23

The time it takes for the number of nuclei of the isotope in a sample to halve, or the time it takes for the count rate (or activity) from a sample containing the isotope to fall to half its initial level.

Question 24

What is Irradiation?

Answer 24

Irradiation is the process of exposing an object to nuclear radiation

Question 25

Radioactive Contamination?

Answer 25

Radioactive contamination is the unwanted presence of materials containing radioactive atoms in other materials

Question 26

Preventions of Contamination?

Answer 26

- Tongs - Stored in Lead Lined Containers - Protective Clothing - Direct Sample Away - Limit Time of Use

Question 27

Factors affecting how dangerous a radioactive sample is?

Answer 27

- Type of radiation - Its Half-Life - Length of Time exposed to it

Question 28

A sample of C-14 has a count rate of 80 and a Half-Life of 2 days. How long will it take before the count rate is 10?

Answer 28

6 Days

Question 29

What does absorbing electromagnetic radiation do?

Answer 29

Makes electrons move away from the nucleus to a higher energy level

Question 30

What does emitting electromagnetic radiation do?

Answer 30

Makes electrons move closer to the nucleus to a lower energy level

Question 31

What is an isotope?

Answer 31

An element with the same number of protons but a different number of neutrons

Question 32

Why are some atomic nuclei unstable?

Answer 32

If there are too many or too few neutrons

Question 33

When does beta decay occur?

Answer 33

When there are too many neutrons

Question 34

When does Alpha decay occur?

Answer 34

When there are not enough neutrons

Question 35

When will Gamma radiation occur?

Answer 35

After Beta/Alpha radiation, the nucleus is full of energy making it very hot, it will loose energy by emitting a gamma ray

Question 36

What dictates how far it can travel through the air?

Answer 36

How ionising it is; if it's highly ionising it will run out of energy quickly, else, if its poorly ionising they can travel farther before running out of energy

Question 37

How can radiation be damaging?

Answer 37

It can change the way that cells behave and also destroy/damage cells

Question 38

Pros and cons of radiation?

Answer 38

- Can cause damage to living cells but only slightly - Can preserve foods