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Radioactivity Flashcards

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1
Q

What are the three types of ionising radiation that are emitted from unstable nuclei

A

Alpha, Beta and Gamma

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2
Q

What are the reasons for radiation to be emitted from a particle

A
  • they are in a metastable state
  • the nucleus is too large
  • too many protons or neutrons
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3
Q

what is radiation

A

the spontaneous and random emission of energy from the nucleus, there is nothing you can do to affect the rate of radiation like heating it up

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4
Q

how are alpha beta and gamma radiation ionising?

A

because they ionise matter as they pass through it i.e. knock electrons out of orbit

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5
Q

Ionising matter requires … to be done by the radiation - so they … the more they ionise the … their penetration through a material

A

work
slow down
shorter

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6
Q

What is the alpha particle made up of

A

2 protons and 2 neutrons (identical to a helium nucleus)

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7
Q

what is the charge of an alpha particle

A

+2e

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8
Q

what is the heaviest radiation particle

A

alpha, having the mass of 2p+2n

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9
Q

why does alpha particle have the shortest penetration in materials

A

because it has the charge of +2e, is slow and is most ionising

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10
Q

what is a beta particle made up of

A

an electron

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11
Q

what is the charge of a beta particle

A

-1e

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12
Q

how does a beta particle differ from an alpha particle

A

it is quicker so can penetrate through paper but is absorbed by a few mm of aluminium, but weak particles can penetrate through aluminium

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13
Q

what is a gamma ray made up of

A

a high frequency electromagnetic ray that travels at the speed of light

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14
Q

what is the charge of a gamma ray

A

they have no charge thus not being very ionising at all

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15
Q

what can gamma rays travel through

A

they can travel through paper and aluminium but their energy weakens as they travel through dense material like concrete and lead

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16
Q

what is the mass number

A

the total number of protons and neutrons in a nucleus

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17
Q

what is the atomic number

A

the number of protons found in the nucleus of an atom, identical to the charge number of the nucleus

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18
Q

what is an isotope

A

variants of a particular chemical element which differ in neutron number but have the same proton number

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19
Q

what must change in an atom to change the element

A

the protons

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20
Q

why don’t the protons in the nucleus fly apart due to their electrostatic repulsion

A

as the ‘strong’ force overcomes electrostatic repulsion

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21
Q

what is the purpose of the neutrons in the nucleus

A

they add to the strong nuclear force to make the nucleus and atom more stable

22
Q

where is radiation emitted from in an atom

A

the nucleus

23
Q

if a nucleus has too many protons in the nucleus to be stable (or the proton to neutron ratio is too high), what will happen in the nucleus and what radiation will be emitted

A

beta particles: positrons

24
Q

if a nucleus has too many neutrons in the nucleus to be stable (or the proton to neutron ratio is too low), what will happen in the nucleus and what radiation will be emitted

A

beta particles: positrons

25
Q

how does internal exposure to radiation take place

A

when a radionuclide is inhaled, ingested or enters through the bloodstream, only leaves the body when eliminated via excretion or treatment

26
Q

how does external exposure to radiation take place

A

when an airborne radioactive material is deposited on skin or clothes, can sometimes be removed by washing

27
Q

where does cosmic radiation come from

A

gases in the atmosphere, some foods, rocks containing unstable isotopes

28
Q

where does external irradiation come from

A

medically i.e. x-rays, this type of exposure stops when the radiation source is shielded or when the person moves outside the radiation field

29
Q

what can a low dose of radiation over long period of time do to cells

A

great likelihood of damaged cells repairing, can incorporate errors such as mutations when repairing leading to cancer after some or decades of years or just kill off cells

30
Q

why does internal exposure to alpha particles more damaging than external exposure to alpha particles

A

external exposure means skin and clothes are affected by radiation and your skin has three dead layers of skin cells which protect the permanent layers of skin from being damaged. whereas internal exposure directly affects your vital organs without a layer to ionise the alpha particles first.

31
Q

what is background radiation

A

radiation we are all exposed to and is a mixture of natural and man-made sources

32
Q

natural sources of background radiation

A

rocks, food, cosmic rays, atmosphere (radon)

33
Q

man - made sources of background radiation

A

nuclear accidents (chernobyl, hiroshima), medical (X-rays, nuclear imaging), nuclear weapons (Nagasaki)

34
Q

what is Sv

A

a Sievert is a unit of radiation wighted dose also called the effective dose

35
Q

what is Bq

A

how much radiation decays per second Becquarels

36
Q

what is Gy

A

amount of radiation absorbed called gray

37
Q

what is the cheapest and easiest way to record the presence of radiation

A

photographic film, the radiation exposes film in a similar way that light does

38
Q

what does quantised radiation mean

A

it means its been emitted with very specific speeds

39
Q

why would it be difficult to produce a photographic film of gamma radiation

A

as it is a wave not a particle

40
Q

Explain how a Geiger - Muller tube attached to a rate meter works

A

the detector is filled with gas that can be ionised by ionising radiation. if this occurs the gas will conduct electricity for a short moment and this is recorded as 1 count on the ratemeter

41
Q

why is a Geiger - Muller tube more sensitive to alpha and beta particles than gamma rays

A

as gamma rays are less ionising

42
Q

why is it important to use a radioactive tracer that emits gamma rays and not alpha or beta particles when producing an image of the body

A

so that the person isn’t harmed by radiation. the gamma rays tend to pass through objects including cells without much effect. alpha and beta particles are highly/medium ionising therefore very harmful when ingested

43
Q

why is the half life of Technetium suitable for producing medical images

A

long enough to take a precise enough picture of the area affected and short enough not to be harmful to them or other people

44
Q

4 things to consider when answering a radioactivity question

A
  • type of radiation
  • why not the other types
  • half life
  • why not longer or shorter
45
Q

which radioactive source should be used to control the thickness of paper produced

A

alpha as some can go through and some doesn’t

46
Q

why are beta and gamma radiation not suitable for the control of thickness for paper

A

gamma rays can go through most things and beta goes through paper without problem (use beta for production of aluminium foil however)

47
Q

what would a suitable half life for radiation used for controlling paper thickness be

A

5 yrs, as it is not so short that it has to be changed so often and doesn’t give out so much energy quickly but 50 yrs would give energy off too slowly

48
Q

how does the paper system automatically control the thickness of paper

A

if too little radiation goes through the product, then it is too thick so the machine is automated to press the rollers together to decrease the thickness. if too much radiation passes through the material then it is too thin, so the rollers move apart to increase the thickness.

49
Q

For a radioactive tracer being used in a kidney test the patient …

A

drinks water containing a tiny amount of radioactive iodine

50
Q

radioactive tracer being used in a kidney test: for a normal kidney the detector reading goes … then goes … this is because the radioactive water flows … the kidney

A

up
down
out of

51
Q

radioactive tracer being used in a kidney test: for a blocked kidney the detector reading goes … then goes … very slowly

A

up

down - this is because the radioactive isotope has a long half-life so its activity goes down very slowly

52
Q

how to evaluate

A 
RAgES + ReDiES
= 
read
agree
equations
science

re-read
disagree
equations
science

Physics (32 decks)

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