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physics one > atomic structure > Flashcards

atomic structure Flashcards

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1
Q

what is radioactive decay

A

the process in which an unstable nucleus gives out radiation to become more stable

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2
Q

what is alpha decay and what are the properties

A

2 protons and 2 neutrons (He)
- can’t penetrate very far
- strongly ionising

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3
Q

what is beta decay and what are the properties

A

one of the atoms neutrons decay into a proton (stays in nucleus) and electron (which is emitted out)
- penetrate moderately far
- moderately ionising

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4
Q

what is gamma waves and what are the properties

A

waves of electromagnetic radiation
no mass and no charge
- weakly ionising
- penetrating far

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5
Q

explain the radiation of electrons

A

if the nucleus has too many neutrons it can increase the stability by getting rid of a neutron

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6
Q

write the equation for alpha decay of radium 226 (atomic number 88)

A

226 222 4
ra ——- ? + He
88 86 2

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7
Q

write the equation for beta decay of carbon 14 (atomic number 6)

A

14 14 0
C ——-? + e
6 7 -1

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8
Q

write the equation for gamma radiation of radium 226 (atomic number 88)

A

226 226
ra ——— ra + gamma decay (y)
88 88

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9
Q

is the decay process random or is there a specific pattern

A

random

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10
Q

what is the activity of radioactive decay

A

overall rate of decay of all the isotopes in our sample ( measured in Bq)
1Bq = 1 decay per second

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11
Q

define the two definitions of half life

A
  • the time taken for the number of decays to half life
    OR
  • the time taken for the number of radioactive nuclei in a sample to half
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12
Q

what are the steps to calculate the half life

A

work out how many half lives
and then half the number of radioactive nuclei that many times

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13
Q

the half life of a radioactive source is 40 hours, there are initially 3000000 radioactive nuclei in a sample. how many nuclei remain after five days

A

5 x 24 divided by 40 = 3 half lives

3000000/ 2 / 2 / 2 = 375000

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14
Q

what is irradiation

A

the process by which objects are exposed to radiation

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15
Q

what is contamination

A

when radioactive particles get onto other objects. if this radioactive material decays on you, your at risk of being irradiated

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16
Q

which type of radiation is most harmful and why

A

ionising radiation are most harmful because they can interact with molecules inside cells.

17
Q

give an example of how radiation is harmful inside the body

A

if ionising radiation enters the cells, it can ionise DNA causing a mutation. this can cause them to divide uncontrollably possibly causing cancer

18
Q

what determines how harmful radiation is

A

location ( inside/ outside the body), the amount of radiation (dosage), how far away from the source, how long spent near the source, how radioactive it is

19
Q

what is background radiation

A

the radiation that is present all around in the environment

20
Q

what are the sources of background radiation

A

rocks, cosmic rays, nuclear weapon testing, nuclear accidents

21
Q

what are some uses of nuclear radiation in medicine

A

examining of internal organs
radiotherapy

22
Q

how are gamma rays used in raditheraphy

A

gamma emitters direct gamma rays at the cancerous cell, these cells absorb this radiation and the die

23
Q

how is beta radiation used in radiotherapy

A

the beta radiation is placed inside the body either next to or inside the cancerous cells in order for them to absorb the radiation and die

24
Q

what are the side effects of radiotherapy

A
  • other cells also get damaged or killed
    why cancer patients feel so ill
25
Q

what are medical tracers used for and how are they used

A

to check if organs are working properly and diagnose diseases by tracking the movement of isotopes and the radiation they emit around the body

26
Q

why are gamma rays used in medical tracers and what dosage is given

A

they emit gamma radiation which has a shorted half life meaning radiation is only emitted for a shorter amount of time
very small dosage

27
Q

what is nuclear fission and what are the two ways in which it occurs

A

the splitting of large and unstable nuclei into smaller nuclei

spontaneously - fission is unforced and happens by itself
absorbing a neutron - which splits a nucleus by making it even less stable

28
Q

explain the process of nuclear fission using uranium 235

A
  1. start with a large unstable nuclei (uranium 235) and fire a slow moving neutron at at
  2. this addition of a neutron makes it even less stable and causes it to split into two smaller nuclei (daughter nuclei)
  3. this releases two or three more neutrons and loads of energy in the form of gamma radiation
  4. the neutrons are then used again to from more daughter nuclei
29
Q

what are the consequences of an uncontrolled chain reaction of fission

A

the rate of fission is too high emitting too much energy resulting in a nuclear explosion

30
Q

how can nuclear fission be controlled

A
  • control rods - absorb neutrons - slow down reaction
  • the energy released is used to heat up water, producing steam. this is then drive turbines which are connected to an electricity generator
31
Q

what are the pros and cons of nuclear energy

A

pros - uranium is relatively cheap,
produces a large and steady amount of energy, doesn’t produce greenhouse gasses
cons -very expensive to build power plants, hard and expensive to dispose of as it has to be buried underground, risk of a major disaster if something malfunctions

32
Q

what is nuclear fusion

A

when two smaller / lighter nuclei fuse to make a single larger nuclei

33
Q

why does nuclear fusion create so much energy

A

some of the mass from the original smaller nuclei is converted to energy

34
Q

why is nuclear fusion good and what are the issues

A

doesn’t produce radioactive waste
easily make hydrogen which is needed as a fuel

only happens at high pressures and temperatures

35
Q

where does nuclei fusion happen and why

A

inside stars because of the high temperatures and pressures

physics one (9 decks)

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