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PT > Radiation > Flashcards

Radiation Flashcards

1
Q

Explain why this γ-emission does not affect the numbers in the equation.

A

has no charge

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2
Q

Suggest one reason why a nucleus of thallium-208 is unstable.

A

excess neutrons

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3
Q

How to calculate neutrons.

A

Top-Bottom=Neutrons

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4
Q

How to calculate electrons.

A

Same as protons in a neutral atom

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5
Q

From the data given for positions A, B and C, deduce the type of emissions coming from the radioactive source. Explain your reasoning.

A

B- gamma, not deflected, not charged
C- beta, charged particles deflected (L rule)
A- background detected here

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6
Q

State the nature of γ-rays

A

electromagnetic radiation of high frequency and short wavelength

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7
Q

Compare the deflections of the paths of the two types of particle.

A

deflect in opp directions
β deflected more

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8
Q

Describe the path of the beta particles.

A

curved path
deflected towards positively charged plate

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9
Q

State the nature of an α-particle.

A

2 protons, 2 neutrons

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10
Q

Describe how an electric field between two charged plates could be used to determine whether a beam of particles consists of α- or β-particles.

A

α towards negative (plate)
β towards positive (plate)

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11
Q

State what is meant by the term isotopes

A

Different version of the same element.
Same number of protons.
Different number of neutrons (,,a diff nucleon number)

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12
Q

State and explain the type of radiation that must be emitted by the isotope for the leak to be detected.

A

Gamma, can penetrate through the surface and ground and reach the detector unlike the other radiation which are stopped before that

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13
Q

The half-life of the isotope used is 6.0 hours.
Explain why an isotope with this half-life is suitable for a crack in a water pipe.

A

long enough to find leak
short enough to disappear quickly

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14
Q

What is alpha stopped by?

A

thin sheet of paper

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15
Q

What is beta stopped by?

A

thin sheet of aluminium

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16
Q

What is gamma stopped by?

A

thick lead or concrete

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17
Q

What is the alpha charge?

A

+ 3.2 × 10–19

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18
Q

What is the beta charge?

A

-1.6 x 10 -19

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19
Q

The radiation is said to be ionising. Explain what this means

A

atoms lose electrons

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20
Q

α-particles are more strongly ionising and have a shorter range in air than γ-rays.
Use your knowledge of the nature of these radiations to explain these differences.

(2 points)

A

α travels more slowly, loses energy with each collision so range is short

α is charged, somore ionising because it has greater charge

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21
Q

At first, the detector continues to register a low count rate sometimes slightly less than the count rate registered without the source.

The count rate suddenly increases to a very high value when the source is very close to the detector.

Explain these changes in the count rate.

A

Low count rate due to background.
Slightly less due to random decaying fashion.
High due to emission from source.

22
Q

He notices that the count rate registered by the detector every year is slightly smaller than it was the previous year.

Suggest why this is so.

A

Decay of source slowed down =
Activity decreased due to less radioctive nuclei

23
Q

A lead sheet of thickness 10 mm is positioned between the detector and the radioactive source.
State and explain what happens to the count rate on the detector.

A

decreases, not completely absorbed

24
Q

Suggest why the paths of the particles in the magnetic field are curved.

A

the force on the particles is perpendicular to their paths

25
Q

Describe the results from this scattering experiment and explain what they show about the structure of atoms.

A

straight->mostly empty space,
nucleus tiny

small number deflected through large angles-> most mass in nucleus, nucleus is
positive

26
Q

An atom of a different element has a nucleon number of 241.
State two differences between the composition of a nucleus of this atom and a nucleus of americium-241

A

number of protons and neutrons

27
Q

Explain why α-particles are more strongly ionising than β-particles

A

more ke, more charge

28
Q

explain the advantage of this long half-life for the use and safe disposal of a household smoke alarm.

A

low activity, so not hazardous to humans, disposal of old detectors is easy and cheap

29
Q

Household smoke alarm:
type of radioactive emission-
explanation-
Half-life-

A

alpha, highly ionising, 100 years

30
Q

measuring the thickness of aluminium strips produced in a factory
type of radioactive emission-
explanation-
half-life-

A

beta
absorption depends on thickness of aluminium
any number of years

31
Q

State two different sources of background radiation.

A

radon gas (in the air)
rocks OR buildings
food OR drink
cosmic rays

32
Q

Suggest why isotope X2 is stable whereas X1 is not stable.

A

(X2) has fewer (excess) neutrons

33
Q

Suggest one reason why isotopes with very short half-lives are especially hazardous.

A

high dose (of radiation) in short time

34
Q

Deuterium is an isotope of hydrogen (H) with 1 proton and 1 neutron. Nuclear fusion occurs
when two nuclei of deuterium combine. An isotope of helium (He) and a neutron are formed.

A

2
1H
+
2
1H
→
3
2He
+
1
0 n

35
Q

Nuclide equation for fusion.

A

combine, make note of any particles formed

36
Q

During β-decay, one of the neutrons in the nucleus changes. Explain how charge is conserved during this change.

A

charge on neutron = 0 OR total charge on products = 0
charge on proton = +1 AND charge on electron =
–1

37
Q

Describe the composition and structure of a neutral atom of uranium‐235.

A

Very small nucleus surrounded by electrons in the orbit. This many protons=the same number of electrons. This many neutrons.

38
Q

Nuclear fission nuclide equation.

A

Minusing, make note of any particles formed

39
Q

State the proton number, nucleon number, electron number and the value of the charge on an beta-particle.

A

0 protons, o nucleons, 1 electron, -1

40
Q

How to remember the speeds of the different ionising radiation

A

She believes we (community) remember sun brighten

41
Q

Beta decay?

A

plus one proton, one fewer neutron
0
-1 β

42
Q

Alpha decay?

A

minus 2 protons and 4 nucleons
4
2 α.

43
Q

Describe how the americium-241 ionises air

A

alpha emitted hits air molecules and remove electrons from molecules

44
Q

Explain why an extremely high temperature is needed when forcing these two nuclei together.

A

same charge, repels, high quantity of energy to do so…

45
Q

β-particles ionise the air they pass through less strongly than the same number of αparticles. Suggest why this is so.

A

smaller charge
travel faster (unlikely to hit)
force on electrons is less

46
Q

Suggest reasons for using an α‐particle emitter in a smoke detector

A

highly ionizing, ionize air more easily
short range in air, stopped by smoke
do not travel out and cause harm (safe because short range)

47
Q

Explain why the radioactive isotope does not have a very short half-life.

A

(very short half-life) doesn’t allow time for detection before activity has dropped to too low a level

48
Q

Explain why the radioactive isotope does have a very long half-life.

A

(very long half-life) contaminates water supply

49
Q

State and explain two safety precautions necessary for the use of these isotopes in medical procedures.

A
  • reduce exposure time AND lower amount of radiation absorbed
  • increase distance between source and hospital staff AND lower amount of radiation reaches staff
50
Q

Give two reasons why alpha‑emitters are not used as radioactive tracers inside the body.

A

Highly ionising. Radiation would not reach detector outside body.

PT (15 decks)

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