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Physics > P7 atom structure / radioactivity > Flashcards

P7 atom structure / radioactivity Flashcards

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1
Q

what three things make up a particle

A
  • electron
  • proton
  • neutron
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2
Q

state the charges of the three things that make up a particle

A
  • electron = 1-
  • proton = 1+
  • neutron = 0
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3
Q

what are the masses of the three things that make up a particle

A
  • electron = 0.0005
  • proton = 1
  • neutron = 1
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4
Q

what does this diagram show

A

the plum pudding

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5
Q

what are the feature of the plum pudding

A
  • 3D sphere
  • made up of thinly spread positive charge
  • small points of negative charge throughout the positive
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6
Q

what are the features of the nuclear model of the atom

A
  • mostly made up of empty space
  • all positive charge is concerntrated in the nucleus
  • negative charges are tiny electrons orbiting the nucleus
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7
Q

what is the more modern atom model: plum pudding, nuclear model

A

the nuclear model

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8
Q

what are the three different types of radiation

A
  • alpha
  • beta
  • gamma
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9
Q

what is an alpha particle

A
  • 2 neutrons
  • 2 protons
    (a helium nucleus)
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10
Q

what is the charge of a alpha particle

A

2+

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11
Q

what is the ionisation like of an alpha particle

A

most ionising

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12
Q

describe the penetration of an alpha particle

A

very poor - stopped by paper

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13
Q

what is the range of an alpha particle like

A

1cm in air

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14
Q

what is a beta particle

A

a fast electron

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15
Q

what is the charge of a beta particle

A

-1

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16
Q

what is the ionisation like of a beta particle

A

moderatley ionising

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17
Q

describe the penetration of beta particle

A

moderately - stopped by thin aluminium

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18
Q

what is the range of a beta particle

A

1m

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19
Q

what is a gamma particle

A

electromagnetic waves

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20
Q

what is the charge of a gamma particle

A

0

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21
Q

what is the ionisation of a gamma particle like

A

weakly

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22
Q

desribe the penetration of gamma particles

A

highly penetrated - only stopped by dense thick lead

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23
Q

what is the range of gamma particles

A

1km

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24
Q

what is the mass number and proton number of a alpha particle

A

mass = 4
proton = 2

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25
Q

define decay

A

when a nucleus goes from an unstable state to a stable state by emitting radiation

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26
Q

what is the mass number and proton number of a beta particle

A

mass = 0
proton = -1

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27
Q

where are the electrons located in an atom

A

on shells orbitting the nucleus

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28
Q

what is the radius of an atom

A

10^-10 m

29
Q

what do like charges do

A

repel

30
Q

what do opposite charges do

A

attract

31
Q

define half life

A

the time it take the number of radioactive nuclei in a smaple to decrease by 50%

32
Q

how does the half life vary between isotopes and why

A

massively due to thhe instability of the nucleus

33
Q

if the half life of a element is short what is the activity like

A

large activity (unstable)

34
Q

if the half life of a element is long what is the activity like

A

little activity (stable)

35
Q

what are the uses for alpha radiation

A

smoke detectors

36
Q

what are the uses of gamma radiation

A
  • tracers (diagnosing cancer)
  • sterlising (kills bacteria)
  • treating cancer (kills cells)
37
Q

what are the uses of beta radiation

A
  • measuring the thickness of paper
  • tracers
38
Q

why is it favoured for the half life of radioactive equipment to be long

A

so it doesn’t need replaceing as often
[tracers need short halflife = doesnt cause prolonged damage inside someone]

39
Q

what safety action can someone they handle radioactive materials often

A
  • move far away from it when it is in use
  • wear a lead apron
40
Q

what is the definition of an isotope

A

an atom of the same element with the same number of protons but a different number of neutrons

41
Q

when does neutron emission occur

A

when an alpha paeticle collides with a nucleus

42
Q

define ionisation

A

when an atom turns into an ion by an electron being removed

43
Q

define irradiation

A

when something is exposed to ionising radiation, but do not become radioactive

44
Q

define contaminated

A

the unwanted presence of a radioactive substances

45
Q

What is nuclear fission

A

Nuclear fission is the splitting of a heavy nucleus into smaller nuclei, initiated by neutron absorption, releasing energy and additional neutrons, which can cause a chain reaction.

46
Q

who discovered the plum pudding model with the beam of particles (electrons exist)

A

J.J thompson

47
Q

what is the set up for the alpha scattering experiment

A
  • firing alpha particles into gold foil
48
Q

who first identified the concept of atoms (they cannot be divided)

A
  • democritus - greek philosopher - and John Dalton
49
Q

who found the existance of the nucleus

A

Rutherford (the alpha cattering experiment)

50
Q

who discovered the electrons exist on shells

A

Bohr

51
Q

who developed the idea of electrons in clouds rather than a strict orbit

A

Erwin Shrodinger

52
Q

whoe showed the existance of neutrons

A

James Chadwick

53
Q

State the three main outcomes from the alpha scattering experiments

A
  • most particles passed through the gold foil = atoms are mostly empty space
  • some were deflected at small angles = positve centre of atom
  • very small number were deflected at large angles = small and dense
54
Q

what are the units of the rate of decay

A

Becquerel (Bq)

55
Q

define background radiation

A

background radiation refers to the low-level ionising radiation that is always present in the environment. This radiation comes from a variety of natural and man-made sources

56
Q

what are the man-made sources of background radiation

A
  • Medical procedures
  • Nuclear power plants
  • Fallout from nuclear tests
57
Q

what are the risks of using radiation

A
  • lead to tissue damage via ionisation
  • increases risk of cancer
  • high doses cause radiation sickness
58
Q

what are the natural sources of background radiation

A
  • Cosmic rays
  • Radioactive materials in the ground
  • Food and drink
59
Q

what units is background radiation measured in

A

Sieverts (Sv)

60
Q

explain the energy release involved in nuclear fission

A

as the nucleus splits into two smaller nuclei, lots of energy is released because the ‘products’ have less mass than the reactants

61
Q

what makes nuclear fission a chain reaction

A

as one neutron hits a uranium atom, at least 3 more neutrons are released

62
Q

what is used in nuclear power stations to control the chain reactions

A

a control rod moves up and down, absorbing neutrons, lower the rods are the more neutrons absorbed and slower the reaction

63
Q

what is nuclear fusion

A

when two small nuclei collide and fuse together to form a large nucleus

64
Q

explain the energy release in nuclear fusion

A
  • when the larger nucleus is formed energy is released in the process
  • the colliding nuclei need enough kinetic energy to fuse
  • they release a lot of energy after that
65
Q

why do the small nuclei in nuclear fusion need enough kinetic energy to fuse

A

because otherwise they will repel each other and not fuse because theyre both 2 positive charges

66
Q

explain how nuclear fusion occurs

A
  • gas in fusion reactor is heated by an electrical current
  • gas becomes so hot it forms a plasma of small nuclei
  • plasma is contained using a magnetic field to prevent it touching the container walls
  • hydrogen nuclei fuse to form helium nucleus
67
Q

how is the plasma in the fusion reactor contained

A

using a magnetic field around it because the plasma is positive and the electricity is negative

68
Q

how does a moderator work in nuclear fission

A

it slows down the neutrons to increase reaction speed - fast neutrons won’t be absorbed

Physics (13 decks)

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