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Physics > Radioactivity > Flashcards

Radioactivity Flashcards

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1
Q

how is radiation absorbed or emitted

A

when electrons jump between energy levels

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2
Q

what an energy levels

A

cet distances from the nucleus that the electrons can orbit

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3
Q

what is the size of a molecule in standard form

A

10 to the power of -9

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4
Q

what is the size of an atom in standard form

A

10 to the power of -10

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5
Q

what is the size of a nucleus in standard form

A

10 to the power of -15

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6
Q

what is an isotope

A

an atom that has the same number of protons but a different number of neutrons

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7
Q

how is an ion formed

A

when electrons are lost or gained and the atoms gain an overall charge

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8
Q

what are 2 ways electrons can leave an atom

A
  1. absorbing EM radiation so that they can escape the pull of the nucleus
  2. being hit by a particle such as alpha or beta radiation
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9
Q

radiation is r_____

A

random

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10
Q

what are the 4 types of ionising radiation

A

Alpha
Beta
Gamma
neutron

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11
Q

where is ionising radiation emitted from

A

unstable nuclei

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12
Q

what is the structure of alpha radiation

A

helium nucleus with 2 protons and 2 neutrons

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13
Q

what is ionizing radiation

A

radiation that can cause atoms to ionize

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14
Q

what is the relative charge of alpha radiation

A

+2

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15
Q

what is the ionising power of alpha radiation

A

heavily ionising

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16
Q

what is the penetrating power of alpha radiation and what can it be stopped by

A

very low, stopped by paper

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17
Q

what is the relative charge of B- radiation

A

-1

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18
Q

what is the relative charge of B+ radiation?

A

+1

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19
Q

what is the relative charge of gamma radiation?

A

0

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20
Q

what is the relative charge of neutron radiation?

A

0

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21
Q

what is the ionising power of Beta radiation

A

weakly ionising

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22
Q

what is the ionising power of neutron radiation

A

not directly ionising

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23
Q

what is the ionising power of gamma radiation

A

not directly ionising

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24
Q

what is the penetrating power of Beta radiation and what can it be stopped by

A

low, stopped by aluminium

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25
Q

what is the penetrating power of neutron radiation

A

high

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26
Q

what is the penetrating power of gamma radiation and what can it be stopped by

A

very high, stopped only by thick lead

27
Q

what is background radiation

A

low levels of radiation that is present around you all the time

28
Q

what 6 factors make up background radiation

A

radon gas
ground and buildings
medical
nuclear power
cosmic rays
food and drink

29
Q

what is the largest contributor to background radiation

A

radon gas

30
Q

what is radon gas

A

a radioactive gas that is released when uranium rocks decay

31
Q

what are the 2 tools used to measure radioactivity

A

geiger-muller tube
dosimeter

32
Q

what is GM tube

A

used to detect radiation

33
Q

how does a GM tube work

A

contains argon gas which will be ionised if radiation enters. the released electrons can travel down a thin wire and be detected as radiation

34
Q

what is radiation measured in

A

Becquerel

35
Q

what are the parts of a dosimeter

A

photographic film
open window
different sections with different levels of materials to detect different types of radiation

36
Q

what is an early model of the atom

A

Plum pudding model

37
Q

who created the plum pudding model and what did it show

A

Thompson, atoms had an overall positive charge with negative electrons scattered across it

38
Q

what did Rutherford discover

A

positively charged nucleus

39
Q

describe rutherfords experiment

A

he shot alpha particles at a piece of thin gold foil and used a circular fluorescent screen to detect where they landed. he realised that although many of the alpha particles travelled straight through some of them were deflected. this was caused by a positively charged nucleus

40
Q

what did the Bohr model show about atoms

A

that electrons orbit the nucleus in well-defined energy levels

41
Q

what are the 2 types of Beta-decay

A

Beta -
Beta +

42
Q

how is beta-decay formed?

A

when a neutron in the nucleus of an unstable atom decays to become a proton and an electron. the proton stays within the nucleus but the electron is emitted from the nucleus

43
Q

how is beta + decay formed

A

when a proton in the nucleus decays to become a neutron and a positron which is emitted

44
Q

how does the atomic and mass number change after beta-decay

A

the mass number stays the same
the atomic number increased by 1

45
Q

how does the atomic and mass number change after beta+decay

A

the mass number stays the same
the atomic number decreased by 1

46
Q

how does the atomic and mass number change after alpha decay

A

mass number reduced by 4
the atomic number was reduced by 2

47
Q

how does the atomic and mass number change after gamma radiation

A

no change

48
Q

how does the atomic and mass number change after neutron decay

A

mass number - 1
the atomic number stays the same

49
Q

what unit is used to measure radioactivity

A

Bq

50
Q

what half-life

A

the time it takes for half of the unstable atoms to decay

51
Q

what are 4 uses of gamma rays?

A

kill cancer cells
sterilise surgical equipment
diagnose and find cancer
preserve food

52
Q

what radiation is used in smoke alarms

A

alpha radiation

53
Q

what is the use of beta decay and how is it used

A

control the thickness of the paper, if beta decay cannot get through the paper will be too thick so it will be flattened more

54
Q

why is ionising radiation dangerous to humans

A

can knock electrons of atoms turning them into ions, this can cause mutation in DNA cells which can lead to cancer

55
Q

what are 3 precautions to lower radiation damage to humans

A
  1. limit the time to exposure
  2. wear protective clothing
  3. increase distance from the source
56
Q

what is irradiation

A

ionising radiation from an external source travelling to the body

57
Q

what are the 2 types of contamination

A

external
internal

58
Q

what is external contamination

A

when radioactive materials come into contact with a person’s hair, skin or clothes

59
Q

what is internal radiation

A

when a radioactive source enters the body by beating eaten or drunk

60
Q

what is a medical tracer

A

substance that are used in biological processes and contain a radioactive isotope

61
Q

how does a PET scanner work

A
  1. a tracer is taken that produces positrons
  2. when the positrons come into contact with electrons in the body the 2 particles annihilate each other and form gamma rays
  3. the gamma rays are detected by the PET scanner
62
Q

how can tumours be treated internally

A

using a radioactive isotope that is injected into the body, which will travel to tumours and kill the cancerous cells with ionising radiation

63
Q

how can tumours be treated externally

A

several beams of gamma rays are fired from different positions towards the cancer, the beams can damage the cancer. by moving the beam the amount of ionising radiation received to surrounding tissue is reduced

Physics (9 decks)

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