p6.1 - yr9 bits

Question 1

what happens if a proton number changes of an element?

Answer 1

the element changes

Question 2

what is a radioactive substance?

Answer 2

one that contains unstable nuclei that become stable by emitting nuclear radiation

Question 3

what is an alpha particle made of?

Answer 3

2 protons,2 neutrons (ie. a helium NUCLEUS)

Question 4

what is an alpha particle stopped by?

Answer 4

paper/skin

Question 5

compare ionising properties of alpha, beta, gamma

Answer 5

alpha - high ionising
beta - moderately ionising
gamma - low ionising

Question 6

what is beta radiation stopped by?

Answer 6

thin aluminium

Question 7

what is gamma radiation stopped by?

Answer 7

thick lead/concrete

Question 8

speed of alpha beta gamma radiation?

Answer 8

alpha - slow
beta - fast
gamma - speed of light (EM wave)

Question 9

differences between gamma radiation and alpha and beat

Answer 9

gamma is a wave

alpha and beta are particles

Question 10

range of alpha beta gamma radiation?

Answer 10

alpha - few cm in air
beta - 1m in air
gamma - unlimited range in air

Question 11

what is a beta particle?

Answer 11

a fast moving electron

Question 12

how does ionising living cells affect them?

Answer 12

kills/damages them

Question 13

what is the most dangerous kind of radiation inside the body?

Answer 13

alpha (more heavily ionising) than beta/gamma

- many ions created inside body

Question 14

what is ionisation?

Answer 14

process of turning a neutral atom/molecule into an ion

Question 15

why is nuclear radiation so dangerous to the human body?

Answer 15

• nuclear radiation is highly ionising
• if ions are created near the body, they will react with the cells of the body
• which are them damaged
• as the cells are ionised, they become highly reactive and continue to replicate
• giving rise to a tumour

Question 16

what kind of radiation is most and least dangerous outside the body?

Answer 16

most - gamma (can penetrate skin)

• although lower chance of ionisation
• ions created damage cells of organs

least - alpha (can’t penetrate skin)
- most skin cancer = cut off

Question 17

what kind of radiation is the least dangerous inside the body?

Answer 17

gamma - can penetrate body and leave it

• ions created are outside body, not damage cells

Question 18

how are penetrating power and ionisation potential related?

Answer 18

higher penetrating power = lower ionisation potential

as it passes straight by them, does not interact with particles

Question 19

charges on alpha beta gamma radiation

Answer 19

alpha +2 (helium nucleus)
beta -1 (electron)
gamma = 0

Question 20

how can you separate alpha beta gamma radiation?

Answer 20

1) pass beam of radiation between positive and negative metal plate
2) alpha attracted towards negatively charged metal plate
3) beta towards positively charged metal plate
4) gamma experiences no deflection

Question 21

how is the angle of deflection of alpha and beta particles in a magnetic field different?

Answer 21

beta - much greater than alpha (smaller mass)

Question 22

what is background radiation?

Answer 22

nuclear radiation around us from environment/space

Question 23

can a radioactive source only emit one kind of radiation?

Answer 23

no, can emit all three types

Question 24

what does the likelihood of a radioactive source emitting all three sources of radiation depend on?

Answer 24

depends on mass and size of the unstable isotope

bigger/heavier it is, higher likelihood of emitting all 3 types

Question 25

why are alpha and beta particles highly ionising?

Answer 25

• as they possess a charge

- so they can exert forces of attraction/repulsion on other particles

Question 26

in what kind of decay does the nucleus of an atom change?

Answer 26

only alpha and beta

• not gamma as nucleus stays same, but only loses energy

Question 27

how does nucleus change in alpha decay?

Answer 27

• loses 2 protons and 2 neutrons

Question 28

how does the nucleus change in beta decay?

Answer 28

• neutron number decreases by 1
• proton number increases by 1

as a neutron turns into a proton and an electron
(only electron ejected from nucleus at a high speed)

Question 29

how does the nucleus of an atom change when gamma radiation is released?

Answer 29

no change, as it only emits energy

Question 30

if radioactive decay is a random process how can you detect the half life of one?

Answer 30

for a large number of nuclei in a radioactive substance

- you can work out time for half the nuclei to decay

Question 31

what is the half life of a radioactive substance?

Answer 31

time taken for half the unstable nuclei to decay

Question 32

what is activity of a radioactive substance?

Answer 32

number of nuclei decay every second

Question 33

what is used to measure activity of a radioactive substance?

Answer 33

geiger counter

Question 34

how do you calculate the half life of a radioactive substance on a graph?

Answer 34

see the time taken for the activity to half

Question 35

why do unstable atoms decay?

Answer 35

in order to become stable