P8

Question 1

Define radioactive decay (3)

Answer 1

process when unstable nuclei “decay”

emit particles or waves to form more stable nuclei

occurs spontaneously + randomly over time

Question 2

What does a radioactive nucleus emit when it decays (3)

Answer 2

alpha particles

beta particles

gamma rays

Question 3

Define ionising radiation (2)

Answer 3

stream of radioactive rays/particles

has enough energy to cause other atoms to lose electrons + become cations

Question 4

Detection of Radioactivity

Answer 4

Geiger-Muller tube

Question 5

Alpha particle description

Answer 5

positively charged particle

has two protons + two neutrons

Question 6

Alpha particle penetration (2)

Answer 6

4-10 cm of air

stopped by sheet of paper

Question 7

Alpha particle electric charge

Answer 7

+2

Question 8

Alpha particle relative atomic mass

Answer 8

4 atomic units

Question 9

Alpha particle ionising effect

Answer 9

strongly ionising

Question 10

Alpha particle effects of magnetic/electric field

Answer 10

weakly deflected in opposite direction to beta

Question 11

Use of alpha particles (5)

Answer 11

smoke detectors

radiation produces ions in air

ions conduct electric current

smoke absorbs some of alpha particles = reduces ion number + current

sets off alarm

Question 12

Beta particle description

Answer 12

high energy electron from a nucleus

Question 13

Beta particle electric charge

Answer 13

-1

Question 14

Beta particle relative atomic mass

Answer 14

1/1860th of an atomic unit

Question 15

Beta particle penetration power (2)

Answer 15

1 m of air

stopped by few mm of aluminum

Question 16

Beta particle ionising effect

Answer 16

weakly ionising

Question 17

Beta particle effect of magnetic/electic field

Answer 17

strongly deflected in opposite direction to alpha

Question 18

Gamma ray description

Answer 18

high energy/short-wavelength electromagnetic wave released from an atom

Question 19

Gamma ray electric charge

Answer 19

electrically neutral

Question 20

Gamma ray relative atomic mass

Answer 20

no atomic mass

Question 21

Gamma ray penetrative power (3)

Answer 21

strong penetration at speed of light

no material can completely stop it

strength can be reduced by several cms of lead + metres of concrete

Question 22

Use of beta particles (2)

Answer 22

medical tracers - checking thickness of material

number of beta particles passing through material is reduced when thickness is increased

Question 23

Ionising effect of gamma rays

Answer 23

weakly ionising

Question 24

Magnetic/electric field effect on gamma ray

Answer 24

unaffected

Question 25

Use of gamma rays

Answer 25

medical industry - sterilisation of medical equiptment + to treat cancer

Question 26

Define background radiation

Answer 26

radiation from artificial + natural sources

Question 27

What is meant by radiation being ionising

Answer 27

radiation collides with atom --> removes electrons from atom causing it to become charged

Question 28

What happens when a nucleus emits an alpha particle

Answer 28

loses 2 protons nucleon number decreases by 4

Question 29

What happens when a nucleus emits a beta particle (3)

Answer 29

proton number increases by 1 - 1 neutron changes to proton gains 1 electron electron emitted as beta particle

Question 30

What happens when a nucleus emits a gamma ray (2)

Answer 30

wave carrying energy is emitted no change to proton or necleon number

Question 31

Define half-life (2)

Answer 31

time taken for half the radioactive nuclei to decay measured in becquerels

Question 32

Define becquerels

Answer 32

1 becquerel = 1 nucleus decay and emits radiation per second

Question 33

Dangers of alpha particles (2)

Answer 33

dangerous to human tissue - strong ability to ionise other particles cannot penetrate skin

Question 34

Dangers of gamma radiation (2)

Answer 34

high penetrating power cell has repair mechanisms that make ordinary levels of gamma radiation harmless

Question 35

Safety precautions when handling radiation (4)

Answer 35

forceps when moving radioactive sources not pointing radioactive sources at living tissue store radioactive material in lead containers check surrounding for radiation level above background level

Question 36

Example of radioactive iodine to treat cancer in thyroid (2)

Answer 36

thyroid cells absorb more iodine than other body parts iodine absorbed by cancer cells which kills them

Question 37

Define radiotherapy

Answer 37

radiation fired at cancer cells to kill them

Question 38

Define radioactive carbon dating (3)

Answer 38

carbon contains small amount of radioactive isotope carbon-14 (half-life of 5700 years) living material dies = carbon-14 will decay ratio of carbon-14 nuclei to non-radioactive carbon-12 can calculate age