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PHYSICS GCSE > ATOMIC STRUCTURE > Flashcards

ATOMIC STRUCTURE Flashcards

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1
Q

what is the alpha scattering experiment

A

the alpha particles were shot at the gold nucleus some particles were refracted straight back meaning the mass of the atom must be concentrated in the centre, some particles were deflected which means the nucleus was positive. Lastly some of the alpha particles went straight through meaning that the atom was mostly free empty space. this formed the nuclear model which had a positive nucleus and contained mostly free space

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2
Q

Describe the current model of the atom

A

The centre of an atom is an tiny positively charged nucleus. this is made up of protons and neutrons and is the source of most of the atoms mass. Most of the atom is empty space, Electrons orbit the nucleus at set energy levels

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3
Q

the atomic number of an atom is its….

A

number of protons

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4
Q

what are isotopes

A

isotopes are atoms with the same number of protons different number of neutrons

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5
Q

the mass number of an atom is its

A

number of protons + number of neutrons

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6
Q

what is radioactive decay

A

when unstable isotopes give out radiation to become more stable

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7
Q

radioactive substances give out radiation what else do they release and why

A

neutrons to rebalance their atomic and mass numbers

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8
Q

what is ionising radiation

A

it is radiation that knocks electrons off atoms creating positive ions

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9
Q

what is alpha radiation

A

is when an alpha particle is emitted from the nucleus

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10
Q

what is an alpha particle

A

a helium atom

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11
Q

alpha particles are (ionisation and penetration)

A

strongly ionising because of their size

do not penetrate far into materials and is stopped quickly

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12
Q

what is alpha radiation absorbed by

A

paper

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13
Q

what is alpha radiation used for and how

A

alpha radiation is used in smoke detectors
it ionises air particles causing current to flow, if there is smoke in the air it binds to the ions meaning current will stop and the alarm will sound

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14
Q

what is beta radiation

A

it is a fast moving electron released from the nucleus

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15
Q

what is a beta particle

A

they have no mass

and it is an electron

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16
Q

beta particles are (ionisation and penetration)

A

beta particles are moderately ionising

beta particles penetrate moderately far into materials

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17
Q

what is beta radiation absorbed by

A

by a sheet of aluminium

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18
Q

for every beta particle emitted…..

A

a neutron in the nucleus has turned into a proton

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19
Q

what are gamma rays (radiation)

A

gamma rays are waves of electromagnetic radiation released by the nucleus

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20
Q

gamma rays are (ionisation and penetration)

A

deeply penetrating they penetrate far into materials

they are weakly ionising

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21
Q

what are gamma rays absorbed by

A

they are absorbed by thick sheets of lead or concrete

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22
Q

in nuclear equations the alpha particle can be written as….

A

an helium atom 4

2

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23
Q

what type of radiation is given off 8 8
Li—->Be + radiation
3 4

A

beta

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24
Q

in nuclear equations the beta particles can be written as……

A

an electron 0

-1

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25
Q

what is the nuclear equation for 219 emitting an alpha
Rn particle
86

write down the equation

A

219 215 4
Rn ——> + He
86 84 2

26
Q

do gamma rays change the mass or charge of the nucleus

A

NO

27
Q

how is radiation measured and what does it record

A

Geiger muller tube and counter and it records the count rate

28
Q

what is half life

A

half life is the amount of time taken for the number of radioactive nuclei in an isotope to halve

29
Q

what does a short half life mean and is it dangerous

A

a short half life means the activity falls quickly because the nuclei are very unstable and rapidly decay. Sources with a short half life are dangerous for the radiation they emit at the start then become safe quickly

30
Q

what does a long half life mean and is it dangerous

A

a long half life means the activity falls slowly because most of the nuclei don’t decay for a long time, which means the source will emit small amounts of radiation for a long time. This can be dangerous because nearby areas are exposed to radiation for a very long time

31
Q

the initial count rate of a sample is 40cps calculate the decline in count rate after three half lives as a ratio

A

40/2=20 one half life
20/2=10 two half lives
10/2=5 three half lives

5:40= 1:8

32
Q

sources of background radiation

A

cosmic rays, air, food, rocks

33
Q

what is irradiation

A

when objects are exposed to radiation

34
Q

what is contamination

A

contamination is when radioactive particles get onto objects

35
Q

how to reduce the effects of irradiation

A

keeping sources in lead lined boxes

36
Q

reduce effects of contamination

A

wearing gloves and tongs when handling sources

wearing protective suits

37
Q

what radiation is dangerous outside the body and why

A

beta and gamma because they can penetrate the body and get to delicate organs

38
Q

what radiation isn’t dangerous outside the body

A

alpha because its cannot penetrate the skin

39
Q

what radiation is dangerous inside the body

A

alpha because they do its damage in a very localised area

40
Q

what radiation is not as dangerous inside the body

A

beta as radiation is absorbed over a wider area and some passes throughout the body all together

41
Q

what radiation is least dangerous inside the body

A

gamma as it has low ionising power and they mostly pass straight through the body

42
Q

what risks are there using radiation

A

cancer

43
Q

how are gamma emitters used as medical tracers

A

radioactive isotopes are swallowed or injected by a person, the radiation the isotope gives off is detected

44
Q

how is radiotherapy used to treat cancerous tumours

A

gamma rays are directed carefully at a tumour because a high dose of gamma rays will kill living cells, the cancerous cells will be destroyed without damaging too many normal healthy cells

45
Q

why would some patients not want to use medical tracers

A

medical tracers use radiation and this poses a risk to the human body as it can cause cell damage or cell mutation, patients may think the risks are too serious and want other tests to be performed

46
Q

what is nuclear fission

A

nuclear fission is splitting a larger nucleus into smaller one

47
Q

what has to happen before nuclear fission

A

the nucleus has to absorb a neutron

48
Q

what is a chain reaction

A

when the neutrons released are absorbed by another nucleus causing more fission to occur

49
Q

what controls the amount of energy produced by fission in a nuclear reactor

A

it is controlled b how quickly the chain reaction can occur this is done by using control rods which are lowered and raised inside a nuclear reactor to absorb neutrons slow down the chain reaction and control the amount of energy released

50
Q

how do nuclear weapons work

A

uncontrolled chain reactions which quickly leads to lots of energy being released as an explosion

51
Q

what is nuclear fusion

A

nuclear fusion is when two light nuclei join to form a larger nucleus and a small amount of mass is turned into energy

52
Q

describe the process of nuclear fission use the information above

A

nuclear fission is when the nucleus splits into smaller lighter nuclei, the atom has absorbed a neutron and turned into an unstable isotope of the atom, the atom goes through nuclear fission where it splits into daughter nuclei. During nuclear fission it emits neutrons which is absorbed by another nuclei which causes a chain reaction it also emits energy during this fission

53
Q

explain how the distance at which an electron orbits the nucleus may be changed

A

electrons absorb energy in the form of electromagnetic radiation
this causes it to move further away from the nucleus
this makes it move to another energy level.

54
Q

What is the energy released from nuclear fuels inside a nuclear reactor used for?

A

to generate electricity

55
Q

Suggest one reason why scientists continue to try to develop a practical nuclear fusion reactor

A

will give another source of energy

56
Q

what substances are used as a fuels in some nuclear reactors.

A

uranium 235 and Plutonium-239

57
Q

Explain how the energy released by the chain reaction is affected by moving the control rods.

A

lowering the control rods increases the number of neutrons absorbed so energy released decreases

58
Q

Energy is released from nuclear fuels by the process of nuclear fission.
This energy is used to generate electricity.
Describe how this energy is used to generate electricity.

A

(energy) used to heat water and
produce (high pressure) steam
the steam drives a turbine (which turns a generator)

59
Q

lowering the control rods…..

A

reduce the amount of energy released as it increases the amount of neutrons that are absorbed meaning there are fewer neutrons causing chain reactions to slow down

60
Q

where does nuclear fusion happen naturally

A

the sun

61
Q

Tritium is radioactive.
After 36 years, only 10 g of tritium remains from an original sample of 80 g.
Calculate the half-life of tritium.

A

80–40–20–10

36/3=12 years

PHYSICS GCSE (12 decks)

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