p4 - radioactivity

Question 1

what is an isotope

Answer 1

an atom of the same element but with a different mass number

Question 2

how do electrons move to higher energy levels

Answer 2

absorbing electromagnetic radiation

Question 3

a higher energy level is…

Answer 3

further from the nucleus

Question 4

what happens if an electron goes down an energy level

Answer 4

emit electromagnetic radiation

Question 5

what did Dalton theorise

Answer 5

atom was a solid ball

Question 6

what did Thomson do

Answer 6

discover electrons, plum pudding model

Question 7

what did rutherford do

Answer 7

alpha scattering experiment

Question 8

what id rutherford discover

Answer 8

atoms have a central positive nucleus

Question 9

what did Bohr discover

Answer 9

electrons orbit in shells

Question 10

what did Chadwick discover

Answer 10

neutrons

Question 11

define radioactive decay

Answer 11

unstable atomic nuclei changing to become stable by emitting nuclear radiation

Question 12

what are the 3 types of nuclear radiation

Answer 12

beta, gamma, alpha

Question 13

define activity

Answer 13

rate at which a source of unstable nuclei decays

Question 14

what is the unit for activity

Answer 14

becquerels

Question 15

what can radiation be measured on

Answer 15

Geiger-muller tube

Question 16

what do alpha particles consist of

Answer 16

2 neutrons and 2 protons (like helium)

Question 17

define atom ionisation

Answer 17

an atom is ionised if it loses/gains electrons and becomes a charged particle

Question 18

which is the most ionising type of radiation

Answer 18

alpha

Question 19

what are beta particles

Answer 19

high speed electrons

Question 20

when is beta decay emitted

Answer 20

when a neutron turns into a proton

Question 21

which is the most penetrating radiation

Answer 21

gamma

Question 22

what are beta particles blocked by

Answer 22

metal or a few meters of air

Question 23

what are gamma rays

Answer 23

electromagnetic radiation with high energy

Question 24

what are gamma rays blocked by

Answer 24

thick lead, 1m concrete or many km of air

Question 25

what is gammas charge and mass

Answer 25

0

Question 26

what can the ionising effect do

Answer 26

sterilise food and medical equipment, and kill cancer

Question 27

what can the penetrating effect be used for

Answer 27

detecting thickness of materials, or leaks in pipes

Question 28

which are the most harmful outside the body and why

Answer 28

beta and gamma as they can easily penetrate skin

Question 29

define half life

Answer 29

time taken for num. nuclei of radioactive isotope to halve or time taken for its radioactivity to halve

Question 30

when is an object irradiated

Answer 30

when exposed to nuclear radiation

Question 31

why is irradiation dangerous

Answer 31

if a living organism is irradiated, its DNA can be damaged

Question 32

when is an object contaminated

Answer 32

if a radioactive material gets on said object

Question 33

what is a way to prevent contamination

Answer 33

wearing gloves or a mask

Question 34

why is alpha radiation the most dangerous

Answer 34

if it gets in the body, it can damage your cells

Question 35

why do scientists post their work for peer-review

Answer 35

compare findings and spot mistakes, making it more reliable

Question 36

when are we exposed to background radiation

Answer 36

all the time

Question 37

what is a radiation dose

Answer 37

amount of radiation a person receives, measured in sieverts or millisieverts

Question 38

what does a long half life mean

Answer 38

radioactivity falls slowly, but the longer the half life, the longer it will be dangerous

Question 39

why would radioactive sources be injected into the body

Answer 39

for medical imaging, allowing us to explore the body, gamma rays

Question 40

what are the risks of medical imaging

Answer 40

damage to cells, cancer, long enough but not too long half life

Question 41

what is nuclear fission

Answer 41

where a large unstable nucleus splits in 2 and a few neutrons and energy

Question 42

what are some nuclei used for nuclear fission

Answer 42

uranium and plutonium

Question 43

what energy does nuclear fission release

Answer 43

in kinetic energy and gamma

Question 44

why is nuclear fission dangerous

Answer 44

can lead to chain reactions

Question 45

how can we control nuclear fission

Answer 45

control rods are lowered into nuclear reaction when needed to absorb neutrons

Question 46

what is nuclear fusion

Answer 46

2 small nuclei joining together to form one nucleus and energy and neutrons

Question 47

where does nuclear fusion naturally occur

Answer 47

stars

Question 48

what type of radiation do smoke alarms use

Answer 48

alpha

Question 49

how do smoke alarms work

Answer 49

alpha particles ionise molecules of air forming ions and electrons which are attracted to a pair of charged plates, when the ions and electrons hit the plates they provide a small amount of electricity which stays constant and is monitored by the smoke alarm

Question 50

why are alpha particles suitable for smoke alarms

Answer 50

When smoke enters the smoke detector, the smoke particles near the radioactive source absorb many of the alpha particles before they can ionise the air between the charged plates, the number of ions and electrons between the charged plates therefore decreases and so the current which is passed between the charged plates also decreases, the smoke detector notices the decrease in current and sets off the alarm.

Question 51

what is thickness monitoring and what particle is used

Answer 51

The amount of radiation which passes through a material can be detected and used to control the thickness of the material. The manufacture of aluminium foil (for cooking) is a good example. A radioactive source is placed above the foil and a detector below it. Some of the radiation is absorbed by the foil and some radiation passes through to the detector. The thicker the foil, the less radiation passes through to the detector. Beta particles are used.

Question 52

how can gamma rays treat cancer

Answer 52

High intensity gamma radiation will kill cells. It is used in a technique called radiotherapy to treat cancer by targeting the cancer cells with a beam of radiation and then rotating the source of the beam. The normal cells receive a lower dose of gamma radiation than the cancer cells, where all the rays meet. Radiotherapy aims to kill the cancer cells while doing as little damage as possible to healthy normal cells.

Question 53

what is radioactive tracing

Answer 53

Radioactive tracing is where doctors use radioactive iodine to see if someone’s kidney is blocked. They drink a drink containing a tiny amount of radioactive iodine and a detector is placed near the kidney. If the detector shows the iodine going in and out (graph goes up and then down) then it is ok. If it shows it not come down then it is blocked.

Question 54

how is radioactive tracing safe

Answer 54

half life is 8 days, emits gamma radiation so detected outside of body, decays into a safe product

Question 55

what is sterilisation

Answer 55

Sterilisation means killing the cells of pathogenic microorganisms. Pathogenic means that the microorganisms cause harm (for example, they may cause disease or infection). The technique is used in the sterilisation of food and surgical instruments.

Question 56

what is radioactive dating

Answer 56

The half-life of a radioisotope can be used to measure the age of things. The method is called radiodating. Radiodating can be used to measure the age of rocks and carbon dating can be used to date archaeological specimens.