4.4.2 P1 Atoms and Nuclear Radiation (might come up)

Question 1

Why do unstable nuclei give out radiation

Answer 1

Unstable nuclei undergo decay to become more stable

As they release radiation their stability increases

Question 2

What is the name of the process in which an unstable nucleus gives out radiation to become more stable

Answer 2

Radioactive decay

Question 3

Define the activity of an unstable nucleus

Answer 3

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

Question 4

What is the unit of radioactive decay

Answer 4

Becquerel (Bq)

Question 5

What is count-rate

Answer 5

The number of radioactive decays per second for a radioactive source

Question 6

Give an example of a detector that may be used to measure count-rate

Answer 6

Geiger-Muller tube

Question 7

4 types of nuclear radiation

Answer 7

Alpha particles
Beta particles
Gamma rays
Neutrons

Question 8

What is an alpha particle

Answer 8

2 protons and 2 neutrons

Same as a helium nucleus

Question 9

What is the range of an alpha particle through air

Answer 9

A few centimetres

normally between 2-10cm

Question 10

What will stop beta radiation from passing through a point

Answer 10

A thin sheet of aluminium

Several metres of air

Question 11

What will stop gamma radiation from passing through a point

Answer 11

Several centimetres of lead

A few metres of concrete

Question 12

Why 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

State any changes to mass or charge that occur due to the emission of a gamma ray

Answer 14

Both mass and charge remain unchanged

Question 15

Describe the nature of radioactive decay

Answer 15

Random
Which nuclei decays and when is determined only by chance
It is impossible to predict which nuclei will decay and when

Question 16

Define the half-life of a radioactive isotope

Answer 16

The time it takes for the number of unstable nuclei in a substance to halve
The time it takes for the count rate from a sample to fall to half its initial level

Question 17

What is radioactive contamination

Answer 17

The presence of unwanted radioactive nuclei on other materials

Question 18

What is irradiation

Answer 18

The process of exposing a material to nuclear radiation

The material does not become radioactive

Question 19

Why is it important for the results of studies on the effects of radiation to be published and shared with other scientists

Answer 19

To allow the findings to be independently checked

Peer review

Question 20

What is a beta particle made from

Answer 20

When a neutron turns into a proton and emits a fast moving electron

Question 21

Mass of an electron

Charge of an electron

Answer 21

0

-1

Question 22

What is a gamma ray

Answer 22

An electromagnetic wave

Question 23

Most penetrating radiation

Answer 23

Gamma rays

Question 24

Least penetrating radiation

Answer 24

Alpha