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IGCSE Edexcel Physics Combined (Paper 1) > Radioactivity and Particles > Flashcards

Radioactivity and Particles Flashcards

1
Q

What are the components of an atom?

A

A positively charged nucleus made of:
* Positive protons
* Neutral neutrons

Surrounded by negatively charged electrons which orbit the nucleus.

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2
Q

Where is most of the mass of atoms located?

A

Almost all the mass of the atoms lies in the nucleus.

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3
Q

What is the relative mass and charge of a proton?

A

Relative Mass: 1
Relative Charge: +1

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4
Q

What is the relative mass and charge of a neutron?

A

Relative Mass: 1
Relative Charge: 0

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5
Q

What is the relative mass and charge of an electron?

A

Relative Mass: 0.0005
Relative Charge: -1

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6
Q

What defines isotopes of an element?

A

Atoms of the same element with the same number of protons but a different number of neutrons.

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7
Q

In a nuclide, what does the symbol X represent?

A

X is the symbol of the element.

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8
Q

In a nuclide, what does the mass number A represent?

A

A is the mass (nucleon) number (number of neutrons and protons).

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9
Q

In a nuclide, what does the atomic number Z represent?

A

Z is the atomic (proton) number (number of protons).

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10
Q

What is radioactive decay?

A

The spontaneous transformation of an unstable nucleus into a more stable one by the release of radiation.

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11
Q

Is radioactive decay a random process?

A

Yes, it is a random process.

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12
Q

What occurs during alpha decay?

A

A heavy nucleus emits an alpha particle (helium nucleus - 2A, 4X) and changes to that of a different element.

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13
Q

What is the equation for alpha decay?

A

ZAX → (X - 4A - 2Z) + α

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14
Q

How penetrating are alpha particles?

A

They are highly ionising and weakly penetrating, stopped by a sheet of paper.

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15
Q

What occurs during beta decay?

A

A neutron turns into a proton and emits a beta particle (electron), changing to a different element.

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16
Q

What is the equation for beta decay?

A

ZAX → (X - A - Z) + β

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17
Q

How penetrating are beta particles?

A

They are moderately ionising and moderately penetrating, stopped by a thin sheet of aluminium.

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18
Q

What occurs during gamma decay?

A

A nucleus with excess energy emits a gamma particle after a previous decay.

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19
Q

How penetrating are gamma particles?

A

They are lowly ionising and highly penetrating, stopped by many centimetres of lead.

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20
Q

What is neutron radiation?

A

Occasionally one or more neutrons are ejected from neutron-rich nuclides, also emitted during nuclear fission.

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21
Q

What is the equation for neutron emission?

A

ZAX → (X - A) + 1n

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22
Q

What happens to photographic film when it absorbs radiation?

A

The film gets darker as it absorbs more radiation

The film is initially white and darkens with exposure.

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23
Q

What is the purpose of wearing photographic film badges?

A

To check how much radiation exposure a person has had

These badges are commonly used by workers in radiation environments.

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24
Q

What is a Geiger-Muller tube?

A

A tube that detects radiation by transmitting electrical pulses

Each pulse corresponds to a detected radiation event, producing a clicking sound.

25
Q

What does a higher frequency of clicks from a Geiger-Muller tube indicate?

A

More radiation is present

The clicking sound increases with the amount of radiation detected.

26
Q

What is background radiation?

A

Weak radiation detectable from external sources

It is a normal part of the environment.

27
Q

List three sources of background radiation.

A
  • Cosmic rays
  • Radioactive rocks
  • Food and drink containing radioactive isotopes

Additional sources include fallout from nuclear testing and medical sources like x-rays.

28
Q

How is the activity of a radioactive source measured?

A

In becquerels (Bq)

1 Bq equals 1 decay per second.

29
Q

What does the half-life of an isotope represent?

A

The time taken for half the nuclei to decay or for the activity to halve

It varies for different radioactive isotopes.

30
Q

If the count rate drops from 80 to 40 counts per minute in 2 days, what is the half-life?

A

Around 2 days

This pattern continues with subsequent halving over equal time intervals.

31
Q

Why must background radiation be subtracted in half-life calculations?

A

To obtain accurate measurements of the radioactive source’s activity

Background radiation can interfere with the results.

32
Q

What is one use of long half-life alpha emitters in industry?

A

In smoke detectors

Alpha particles create a current that triggers an alarm when smoke is detected.

33
Q

How are long half-life beta emitters used in thickness monitoring?

A

They detect changes in the thickness of metal sheets during production

A source and receiver are placed on either side of the sheet to monitor beta particle detection.

34
Q

What is the purpose of gamma emitters in sterilisation?

A

To kill bacteria or parasites on equipment so it is safe for operations

Gamma emitters can sterilise through their protective packaging, eliminating contamination risk.

35
Q

What is the role of technetium-99m in medicine?

A

Used as tracers in diagnostic procedures due to its short half-life

It concentrates in certain parts of the body, allowing for effective imaging.

36
Q

What is the significance of the half-life of gamma emitters in diagnostics?

A

Must be long enough for procedures but short enough to not remain radioactive for too long

37
Q

What is the application of cobalt-60 in medicine?

A

Used to destroy tumours with a high dose of radiation

38
Q

Define contamination in the context of radioactive materials.

A

Occurs when a radioactive source has been introduced into or onto an object

39
Q

What is irradiation?

A

When an object is exposed to a radioactive source outside the object

The irradiated object does not become radioactive.

40
Q

How can exposure to radiation affect living cells?

A

Can destroy cell membranes by ionisation or damage DNA, leading to mutations and cancer

41
Q

List three safety measures for radiation exposure.

A
  • Minimising time of exposure
  • Keeping a large distance from the source
  • Using shielding against radiation
42
Q

How should radioactive waste from nuclear reactors be disposed of?

A

Usually by burying it in sealed drums deep underground and remotely handling it after cooling

43
Q

What is nuclear fission?

A

The process of splitting a nucleus

44
Q

What happens when a uranium-235 nucleus absorbs a thermal neutron?

A

It splits into two daughter nuclei and releases energy along with 2 or 3 neutrons

45
Q

What is a chain reaction in nuclear fission?

A

When neutrons released from one fission event induce further fission events in other uranium-235 nuclei

46
Q

What is the function of control rods in a nuclear reactor?

A

To absorb neutrons and regulate the fission process

Usually made of boron.

47
Q

What is the role of the moderator in a nuclear reactor?

A

Slows down neutrons to make them suitable for absorption by uranium-235 nuclei

Usually water is used as a moderator.

48
Q

What is the purpose of a coolant in a nuclear reactor?

A

To prevent the reactor system from overheating

49
Q

Describe the reactor core.

A

A thick steel vessel that withstands high pressures and temperatures and absorbs some radiation

50
Q

What is the function of the building surrounding the reactor core?

A

Acts as a radiation shield to absorb radiation escaping the reactor core

Made of thick reinforced concrete.

51
Q

What is the process of fusing two nuclei to form a larger nucleus called?

A

Nuclear fusion

52
Q

What is the result of the nuclear fusion process in terms of mass?

A

There is a very small loss of mass

53
Q

What accompanies the small loss of mass during nuclear fusion?

A

A release of energy

54
Q

How do the sun and other stars release energy?

A

Through nuclear fusion

55
Q

True or False: Nuclear fusion occurs at low temperatures and pressures.

A

False

56
Q

What prevents nuclear fusion from happening at low temperatures and pressures?

A

The electrostatic repulsion of the protons is too great

57
Q

Fill in the blank: The nuclei that collide and fuse together in nuclear fusion include _______ and hydrogen-2.

A

hydrogen-1

58
Q

What is one of the products formed from the fusion of hydrogen-1 and hydrogen-2?

A

Helium-3

IGCSE Edexcel Physics Combined (Paper 1) (8 decks)

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