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Physics > Atoms and nuclear radiation (4.2) > Flashcards

Atoms and nuclear radiation (4.2) Flashcards

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1
Q

Some atomic nuclei are (…)

A

unstable

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2
Q

The nucleus gives out (…) as it changes to become more (…)

A

radiation

stable

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3
Q

What is radioactive decay?

A

The random process of a nucleus giving out radiation as it changes to become more stable (as nucleus in unstable)

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4
Q

What is activity?

A

the rate at which a source of unstable nuclei decays

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5
Q

What is count-rate?

A

the number of decays recorded each second by a detector

count rate proportional to activity

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6
Q

What is a common example of a detector?

A

a Geiger-Muller tube

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7
Q

What are the 4 particles nuclear radiation may be emitted as?

A
  • an alpha particle
  • a beta particle
  • a gamma ray
  • a neutron
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8
Q

What is the symbol of an alpha particle?

A

𝝰

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9
Q

What does an alpha particle consist of?

A

two neutrons and two protons, it is the same as a helium nucleus

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10
Q

What is the symbol of a beta particle?

A

β

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11
Q

What is a beta particle?

A

a high speed electron ejected from the nucleus as a neutron turns into a proton

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12
Q

What is the symbol of a gamma ray?

A

𝛾

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13
Q

What is a a gamma ray?

A

electromagnetic radiation from the nucleus

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14
Q

What is a a gamma ray?

A

electromagnetic radiation from the nucleus

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15
Q

What is the symbol of a neutron?

A

n

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16
Q

What is ionising power?

A

The ability of radiation, when colliding with atoms, to cause the atom to lose electrons and form ions

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17
Q

What is the penetrating power of alpha, beta and gamma?

A
  • Alpha - skin/paper (least penetrating)
  • Beta - 3mm aluminium foil
  • Gamma - several m thick lead/concrete (most)
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18
Q

What is the ionising power of alpha, beta and gamma?

A
  • Alpha - high (most ionising)
  • Beta - low
  • Gamma - very low (least)

may be classed penetrating power

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19
Q

What is the range in air (before they collide with air particles and stop) of alpha, beta and gamma?

A
  • Alpha - 5cm (shortest range)
  • Beta - 15cm
  • Gamma - (almost) unlimited (longest)

may be classed under penetrating power

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20
Q

Describe the deflection in an electrical field of alpha, beta particles and gamma rays

A
  • alpha particles and beta particles are deflected in opposite directions in an electric field (alpha particles are attracted to the negative electrode, beta to the positive electrode)
  • beta particles are deflected more than alpha particles (reached electrode first) - as alpha particles have a greater charge than beta particles but beta particles have much less mass
  • gamma rays pass straight through the middle of an electrical field (in same direction of force) as they are not charged particles, purely energy
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21
Q

How may an alpha particle be represented in a nuclear equation?

A
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22
Q

How may a beta particle be represented in a nuclear equation?

A
23
Q

The emission of the different types of nuclear radiation may cause a change in what?

A

a change in the mass and /or the charge of the nucleus

24
Q

polonium is required

Write a nuclear equation for the emission of an alpha particle from radon (21986Radon)

A
25
Q

alpha decay causes both the (…) and (…) of the nucleus to (…)

A

mass

charge

decrease

26
Q

nitrogen is required

Write a nuclear equation for the emission of a beta particle from carbon (146Carbon)

A

so the atomic number change changes the type of element, not the mass change

27
Q

Beta decay does not cause the (…) of the nucleus to change but does cause the (…) of the nucleus to increase.

A

mass

charge

28
Q

What is the change in mass or charge of an atom if a gamma ray is emitted?

A

there is no change

gamma is just energy

29
Q

Radioactive decay is (…)

A

random

30
Q

What is the definition for half-life of a radioactive isotope?

A

The time it takes for the number of nuclei of the isotope in a sample to halve

or

the time it takes for the count rate (or activity) from a sample containing the isotope to fall to half its initial level.

31
Q

What is the half-life of this radioactive sample?

A

2 days

32
Q

A radioactive isotope has a half-life of 15 days and an initial count rate of 200 counts per second. Determine the count rate after 45 days

A

45 / 15 = 3

200 / 23 = 25 counts / s

if a net ratio had to be given it would be 8:1

33
Q

What is radioactive contamination?

A

the unwanted presence of materials containing radioactive atoms on other materials

object will remain radioactive as long as the source is on or in it

34
Q

The hazard of radioactive contamination is caused by what?

A

the decay of the contaminating atoms

35
Q

What affects the level of hazard of radioactive contamination?

A

The type of radiation

36
Q

What is irradiation?

A

The process of exposing an object to nuclear radiation.

37
Q

Does an irridiated object become radioactive?

A

no - it is only exposed to it

38
Q

How long does contamination and irritation last?

A

contamination - long time (difficult to remove all contamination)

irritation - short time

39
Q

What are the hazards associated with contamination?

A

Can lead to mutation of DNA in cells, leading to cancers

Contamination risks are the transportation of radioactive materials to other places and potentially contaminating and irradiating other

40
Q

What are the hazards associated with irritation?

A

Irradiation risks DNA damage, leading to the mutation of cells which can lead to cancer.

41
Q

2 needed

How can contamination be managed?

A
  • Wearing of protective clothing such as gloves and hazmat suits.
  • Using tongs/robotics to make sure the material is kept at a distance from the user
42
Q

4 needed

What are some precautions against irradiation?

A
  • Keeping a radioactive source at a safe distance using tongs
  • Using concrete/lead shielding to prevent particles/waves reaching body tissues
  • Not pointing a source in the direction of people
  • Spending as little time as possible in at-risk areas (and using a dosimeter to measure exposure)
43
Q

Why is it important for the findings of effects of radiation on humans to be published and shared?

A

It is important for the findings of studies into the effects of radiation on humans to be published and shared with other scientists so that the findings can be checked by peer review.

44
Q

What is the risk of ionisation?

A

could lead to mutation of DNA in cells, leading to cancer

45
Q

Describe why

What is a use of alpha particles?

A

Alpha particles can be used in smoke detectors.

They are very good at ionising the air.

If smoke particles get into the detector, they will be absorbed by the smoke particles

So a change/decrease in count rate is detected

an exam question simply stated ‘smoke absorbs alpha radiation/particles’ so that might be better

46
Q

Describe why

What is a use of beta particles?

A

Beta particles can be used to check the thickness of paper/thin metals.

A source of beta particles is directed towards the material.

A detector on the other side counts the number of particles that get through.

If more get through, the material is too thin and the rollers being used to thicken/thin the material are moved apart to allow the material to thicken.

As it thickens the count on the detector will drop.

47
Q

3 needed

What are some uses of gamma rays?

A
  • destroying of cells in the sterilisation of medical equipment or on food.
  • to detect and treat cancer.
  • to find leaks in pipes underground.
48
Q

Why can contamination of radioactive material inside the body, that emits alpha particles be highly dangerous?

A

Alpha particles are highly ionising

causes mutation of DNA (forming cancers)

until contaminated material is removed / until radioactive material reaches background radiation levels

49
Q

Why should beta and gamma radiation not be used in smoke alarms?

A

would penetrate smoke particles

so no change in count rate would be seen

50
Q

Why may Banana Equivalent Dose (a source of background radiation) be better to make the public more aware of radiation risks

A

The radiation dose of something can be compared with the radiation dose of a banana

51
Q

Why should the radiation source inside a smoke detector have a long half life?

A

A long half life means the count rate is approximately constant

52
Q

Why would a smoke alarm not work with gamma/beta particles?

A

beta and gamma would penetrate smoke

so count rate would not change

53
Q

Why does a smoke alarm switch on when there are smoke particles?

A

smoke particles absorb alpha particles

54
Q

Why is it safe to use alpha radiation in a house?

A

alpha radiation/particles have a low penetrating power

Physics (25 decks)

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