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physics > Atomic structure > Flashcards

Atomic structure Flashcards

1
Q

how do electrons jump up energy levels

A

they become excited from the energy they get from em radiation

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2
Q

how is em radiation emitted in an atom

A

when an excited atom falls back down to a lower energy level emitting the energy as em radiation

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3
Q

the mass number is……….
the atomic number is………..

A

the mass number is the protons+neutrons and is at the top

the atomic number is the number of protons and is at the bottom

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4
Q

what is ionisation

A

Electrons can also absorb enough energy to leave the atom altogether, this is known as ionisation

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5
Q

what do unstable isotopes do

A

radioactive decay where they emit something to become more stable

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6
Q

what are the 4 types of nuclear radiation

A

alpha
beta
gamma
neutrons

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7
Q

what are alpha particles made up of and what is this the same as

A

2 protons and 2 neutrons same as nucleus of a helium atom

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8
Q

what are the properties of alpha particles

A

large
have 2+ charge
least penetrative-stopped by few cm in air or single sheet of paper
-heavily/most ionising

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9
Q

what does ionising mean

A

how easily something knocks off electrons off atoms it collides with

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10
Q

what is the charge of beta particles

A

-electrons
-charge of -1 with little mass

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11
Q

what are the properties of beta

A

-small
-moderately ionising and penetrative(stopped by several m of air /5mm of aluminium to stop

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12
Q

how are beta particles formed

A

neutron decays to a proton and electron which gets emitted at high speed

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13
Q

what are gamma rays and how are they emitted

A

not particles but em waves that are emitted after alpha and beta radiation as a way of releasing energy

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14
Q

what are the properties of gamma rays

A

-they have no mass or charge so highly penetrative(stopped by thick sheets of lead or multiple m of concrete to stop)
-weakly ionising

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15
Q

how are neutrons emitted

A

if a neutron is making a nucleus unstable it throws out the neutron to make it more stable

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16
Q

what is the equation for alpha decay

A

loses 4 to the mass number and 2 atomic number

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17
Q

what is the equation for beta decay

A

0 to the mass number +1 to the atomic number

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18
Q

what is the equation for neutron emission

A

+1 to the mass number

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19
Q

what is the activity

A

overall rate of decay of all the isotopes in our sample
measured in bq where 1 bq =1 decay per second

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20
Q

what is half life

A

time taken for no of decays(activity)to half

21
Q

what is the count rate

A

the no of decays counted by a geiger muller counter

22
Q

what is irradiation

A

when objects are exposed to any type of radiation

23
Q

what is contamination

A

when radioactive particles get onto other objects

24
Q

what is the harm of contamination

A

the radioactive material you are contaminated with is likely to decay and irradiate you

25
Q

why is ionising radiation most dangerous

A

can enter living cells and interact with molecules inside
this involves dna which they can ionise and cause genetic mutation
in rare cases can cause cancer

26
Q

what 3 things affect dosage

A

-distance from the source
-how radioactive the material is
-how long you are exposed to it

27
Q

how do we minimise irradiation and avoid contamination when we are around radioactive source

A

precautions like
-wearing protective gear like gloves and overalls
-handling item with tongs or tools
-keeping item in lead lined box

28
Q

what is the only way you can spread radiation

A

by holding a radioactive source

29
Q
A
30
Q

what causes radiation sickness and what symptoms does it have

A

recieving large doses of radiation across the entire body which will cause vomiting tiredness or hair less making you ill as most of your cells are killed or damaged

31
Q

how can radiation treat cancer and what is this called

A

can be used by doctors to destroy can cer cells
called radiotherapy

32
Q

what are the 2 ways in radiotherapy that the radioactive source is delivered

A

externally or internally

33
Q

what is the difference between external and internal radiation

A

-external is performed by emitting gamma rays targetted at cancer site at different angles so it gets the highest dose
-internal is performed with beta where it is placed next to or inside cancer

34
Q

what are the side effects of radiotherapy

A

kills other healthy cells in the body causing patients to feel sick

35
Q

how are medical tracers used

A

placing certain radioactive isotopes in a body by injection or swallowing by tracking the radiation they emit to see if certain organs are working by absorbing they right amount

36
Q

how do we minimise risk in treatments

A

use low dose with a short half life

37
Q

what is nuclear fission

A

splitting of unstable large nuclei into smaller nuclei and lots of energy

38
Q

what are the 2 ways nuclear fission can occur

A

-spontaneously-happens on its own(rare)
-absorbing a neutron-makes nucleus less stable

39
Q

what are the steps of nuclear fission

A

1)fire slow moving neutron at unstable nuclei
2)it becomes less stable splitting apart into 2 daughter nuclei
2 or 3 neutrons
and lots of energy in form of gamma radiation

40
Q

how does fission cause a chain reaction

A

the neutrons emitted can react with another unstable nuclei releasing huge amounts of energy(eg a nuclear bomb)-uncontrolled

41
Q

what are control rods and what role do they play in fission

A

control rate of fission which are lowered into reactor to absorb neutrons slowing down rate of reaction

42
Q

what is the energy from fission used for

A

heat up water turn it to steam drive turbines connected to an electricity generator

43
Q

what is nuclear fusion

A

when 2 light nuclei fuse to form single large nuclei and a lot of energy

44
Q

what has nuclear fusion done

A

fuels stars
formed all elements heavier than hydrogen

45
Q

why is so much energy released in nuclear fission

A

some mass of original nuclei is transferred to energy as em radiation instead of new nucleus

46
Q

what are the pros/cons of nuclear fusion

A

pros
no radioactive waste
easily make the hydrogen needed as fuel

cons
-extremely high pressures and temperatures needed
-cant be done on earth

47
Q

what are differences between fission and fusion

A

fusion-only happens inside stars
fission-much less energy produced

48
Q

what is fusion inside stars

A

hydrogen fusing to become helium nuclei

49
Q

Why does fusion only happen at very high temperatures and pressures?

A

To overcome the repulsion of the positively charged nuclei

physics (9 decks)

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