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Physics > radioactivity > Flashcards

radioactivity Flashcards

1
Q

what are atoms

A

building blocks of all matter

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2
Q

what do atoms have in the centre

A

nucleus with electrons orbiting around it

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3
Q

protons

A

positively charged particles with a relative atomic mass of one unit

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4
Q

neutrons

A

no charge, and has a relative atomic mass of one unit

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5
Q

electrons

A

negative charge with almost no mass

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6
Q

ionised

A

if an atom loses electrons

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7
Q

atomic number

A

number of protons in an atom

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8
Q

mass number

A

total number of particles in the nucleus of an atom

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9
Q

isotopes

A

atoms of the same element that have the same number of protons but a different number of neutrons

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10
Q

why are isotopes unstable

A

due to imbalance of protons and neutrons

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11
Q

what do unstable nuclei emit

A

radiation to become more stable

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12
Q

forms of radiation

A

high energy particle
wave

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13
Q

radioactive decay

A

process of emitting radiation

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14
Q

what process is radioactive decay

A

random process

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15
Q

nuclear radiation

A

when an unstable nucleus decays it emits radiation

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16
Q

types of radiation

A

alpha
beta
gamma

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17
Q

alpha particles

A
  • helium nucleus
  • 2 protons and 2 neutrons
  • charge of +2
  • can be affected by an electric field
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18
Q

beta particles

A
  • fast moving electrons
  • produced in nuclei when a neutron changes into a proton and electron
  • charge of -1
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19
Q

gamma rays

A
  • EM waes
  • highest energy of EM waves
  • no charge
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20
Q

range in air- alpha

A

few cm

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21
Q

beta- range in air

A

few 10s of cm

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22
Q

range in air- gamma

A

infinite

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23
Q

alpha penetration and ionisation

A

stopped by paper
high

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24
Q

beta penetration and ionisation

A

stopped by a few mm aluminium
medium

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25
Q

gamma penetration and ionisation

A

REDUCED by few mm of lead
low

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26
Q

alpha decay

A

mass number decreased by 4
atomic number decreased by 2

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27
Q

beta decay - explanation

A
  • neutron changes to proton and e-
  • electron is emmitted
  • proton remains in nuclei
  • completely NEW element formed
28
Q

beta decay

A

mass no. remains the same
atomic no. increased by 1

29
Q

gamma decay

A

mass and atomic number stays the same

30
Q

neutron emmision

A

atomic no. no change
mass number decreases by 1

31
Q

amount of radiation received by a person

A

dose
measured in seiverts

32
Q

how to detect and measure radiation

A

using photographic film
GM tube

33
Q

photohraphic flim

A

becomes darker when absorbing radiation.

34
Q

GM tube

A

transmits an electrical pulse to a counting machine each time it absorbs radiation

35
Q

count rate

A

clicking sound GM tube displays
- the greater the clicks, the more radiation absorbed

36
Q

background radiation

A

the radiation that exists around us all the time

37
Q

background radiation stats

A

radon gas- 50%
rocks and building materials- 15%
medical- 13%
food- 11%
cosmic rays- 10%
other- 1%

38
Q

natural sources of radiation

A

rocks
cosmic rays from space
food

39
Q

man made sources of radiation

A
  • nuclear weapons
  • exposure from medical testing
40
Q

what decays into radon gas

A

uranium

41
Q

cosmic rays from space

A
  • sun emits protons
  • enters atmosphere at high speed
  • collide with air molecules
42
Q

carbon-14

A
  • organic matter contains this
43
Q

radiactive activity

A

the rate at which the unstable nuclei from a source of radiation decays

44
Q

what is activity measured in

A

becquerels (Bq)

45
Q

decreasing activity

A
  • decreases with time
46
Q

half life

A

the time it takes for the number of nuclei of a sample of radioactive isotopes to decrease by half

47
Q

how to calculate half life

A
  • meausre original activity
  • determine half-life of original
  • measure how activity changes over time
48
Q

smoke detectors

A
  • alpha radiation normally ionises the air creating a current
  • alpha emitter is blocked when smoke enters
  • alarm is triggered by a microchip when the sensor no longer detects alpha
49
Q

what is used to measure the thickeness of thin materials

A

beta particles

50
Q

why is beta particles used to measure thickness

A
  • partially absorbs the material
51
Q

why cant alpha be used to measure thickness

A

all of the particles would be absorbed and none would get through

52
Q

radiotheraphy

A

treatment of cancer using radiation

53
Q

radiotheraphy method

A
  • gamma rays directed at cancerous tumour
  • tracer used to track movement of substances in blood
  • PET scan detect emissions from tracer to diagnose cancer and determine location
54
Q

why is gamma used to sterilise

A
  • most penetrating
  • irradiate all sides
  • can sterilise without removing packaging
55
Q

contamination

A

unwanted presence of materials containing radioactive atoms on other materials

56
Q

common cause of contamination

A

radiation leak

57
Q

irradiation

A

process of exposing a material to radiation

58
Q

why is irradiation harmful

A

kills living cells

59
Q

what is irradiation used for

A

method of sterilising

60
Q

source of irradiation

A

danger is from radiation emmitted OUTSIDE the object

61
Q

prevention of irradiation

A

using shielding such as lead clothing because it abosrbs radioactive material

62
Q

source of contamination

A

radiation emitted WITHIN the object

63
Q

prevention of contamination

A

prevented by safe handling of sources and air tight safety clothing because it prevents atoms from getting inside

64
Q

radiation on living cells

A

causes mutations or can kill cells, can from tumours

65
Q

acute radiation exposure

A

skin burns, reduce WBCs

66
Q

handling material

A

use tongs
wear protective clothing
shielding
limit time used for

67
Q

disposure of radioactive waste

A

buried underground to prevent being released to environment

Physics (6 decks)

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