Ionising radiation

Question 1

What is alpha, beta, gamma, and neutron radiation emitted by?

Answer 1

unstable nuclei

Question 2

how often does the process of emitting radiation happen?

Answer 2

it is random

it is not possible to determine when any nucleus will next decay

Question 3

why are some elements radioactive and what does it mean?

Answer 3

they have an unstable nucleus

they will undergo radioactive decay and change into other elements

Question 4

symbol for alpha radiation

Answer 4

α or He

written with a 4 at the top and 2 at the bottom

Question 5

symbol for beta radiation

Answer 5

β or e

written with a 0 at the top and -1 at the bottom

Question 6

symbol for gamma radiation

Answer 6

γ

written with a 0 at the top and bottom

Question 7

what is alpha?

Answer 7

2 protons
2 neutrons

the same as a helium nucleus

Question 8

what is beta?

Answer 8

an electron

Question 9

what is gamma?

Answer 9

an electromagnetic wave

Question 10

charge of alpha

Answer 10

+2

Question 11

charge of beta

Answer 11

-1

Question 12

charge of gamma

Answer 12

0

Question 13

mass of alpha

Answer 13

4

Question 14

mass of beta

Answer 14

1/1835

1/2000

(almost) 0

Question 15

mass of gamma

Answer 15

0

Question 16

ionising power of alpha

Answer 16

very high

Question 17

ionising power of beta

Answer 17

medium

Question 18

ionising power of gamma

Answer 18

very low

Question 19

penetration of alpha

Answer 19

very low

Question 20

penetration of beta

Answer 20

medium

Question 21

penetration of gamma

Answer 21

very high

Question 22

what is alpha stopped by? (3)

Answer 22

• skin
• a few cms of air
• paper

Question 23

What is beta stopped by? (2)

Answer 23

• thin metal sheet

- a few ms of air

Question 24

What is gamma stopped by? (3)

Answer 24

• thick lead
• metres of concrete
• almost unlimited range in air / a few kms

Question 25

What charge and mass does neutron radiation have?

Answer 25

0 charge

1 mass

Question 26

ionising power of neutrons

Answer 26

not directly ionising

Question 27

penetrating power of neutrons

Answer 27

very high

they have no charge and don’t interact strongly with matter

Question 28

What are neutrons stopped by?

Answer 28

can travel through humans and buildings for long distances

Question 29

What is a positron?

Answer 29

a particle with the same size as an electron but an opposite charge

is represented with the same symbol but using a + sign after it

Question 30

affected by magnetic field:

a) alpha
b) beta
c) gamma
d) neutrons
e) positron

Answer 30

alpha: yes
beta: yes, but in the opposite direction to alpha/positron
gamma: no
neutron: no
positron: yes

Question 31

Explain why alpha particles are the most ionising radiation [3]

Answer 31

they have the greatest mass and the greatest charge so can remove electrons more easily from the shells of atoms

Question 32

Explain why radioactive decay is a random process [2]

Answer 32

you cannot predict when a nucleus will decay by emitting radiation