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GCSE Physics > P1 Atomic Structure > Flashcards

P1 Atomic Structure Flashcards

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1
Q

In standard form, what is the radius of an atom?

A

1x10*-10

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2
Q

How does EM absorption effect electrons?

A

Move electrons to a higher energy level further from the nucleus

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3
Q

How does EM radiation emission effect electrons?

A

Moved to a lower energy level, nearer to the nucleus

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4
Q

Define an isotope

A

Same number of protons and electrons, different number of neutrons

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5
Q

Describe the Plum Pudding Model

A
  • JJ Thompson in 1897

- Atoms are balls of positive charge with electrons bedded in it

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6
Q

Describe the Gold Foil Experiment

A
  • 1905, Rutherford and Marsden

- Positive alpha particles fired at a one atom thick sheet of gold foil

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7
Q

Why were some alpha particles reflect back during the gold foil experiment?

A
  • repelled by same charge as alpha particles

- repelling particles are heavier than the alpha particle, or alpha particles would’ve passed through

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8
Q

What are the conclusions of the Gold Foil Experiment?

A
  • mass of atom concentrated in the centre, positive charge

- surrounded by electrons

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9
Q

What did Niels Bohr discover?

A

Adapted the nuclear model to show electrons orbit at specific distances

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10
Q

What did Chadwick discover?

A

Neutrons, increases knowledge of isotopes

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11
Q

Why do atomic nuclei emit radiation?

A

They are unstable

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12
Q

What does type of radiation emitted depend on?

A
  • why the nucleus is unstable

- random and unpredictable

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13
Q

Radioactivity is measured in…

A

Bequerels

1Bq = 1 count / second

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14
Q

What is radioactive decay measured with?

A

Geiger Muller tube

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15
Q

Which type of nuclear decay is most ionising?

A

alpha

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16
Q

Which type of nuclear radiation is most penetrating?

A

Gamma

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17
Q

Describe alpha radiation

A
  • two neutrons, two protons (helium nucleus)

- absorbed by and damages living cells

18
Q

Describe beta radiation

A
  • high speed electrons
  • ejected from the nucleus when a neutron becomes a proton
  • can penetrate through body to inner organs
19
Q

Describe gamma radiation

A
  • em radiation

- passes through living cells without being absorbed or ionising

20
Q

What is another type of nuclear decay?

A

neutron

21
Q

Define radioactive contamination

A

unwanted presence of materials containing radioactive atoms on other materials

22
Q

Why is contamination hazardous?

A

radioactive decay of contaminating atoms

23
Q

What is irradiation?

A
  • exposing an object to nuclear radiation
  • deliberate or accidental
  • object does not become radioactive
24
Q

How can you prevent unwanted irradiation?

A
  • using sources of lowest activity for shortest time
  • wear protective clothing (lead apron)
  • don’t handle sources with bare hands
25
Q

Compare hazards of contamination and irradiation (food, area contaminated with alpha)

A
  • food contaminated with alpha would be more hazardous than gamma as alpha is stronger ionising
  • area contaminated with alpha wouldn’t be dangerous unless it was entered, because it isn’t penetrating
    gamma would irradiate people nearby as it is highly penetrable
26
Q

What is half life?

A

A measure of how long it takes for half of the radioactive atoms to decay

27
Q

Explain what is meant by radioactivity being a random event

A

It is impossible to predict what will decay next

28
Q

Describe isotopes with a short half life

A
  • unstable
  • emit radiation quickly
  • exposure is hazardous
  • aren’t radioactive for long
29
Q

Describe isotopes with long half lives

A
  • more stable
  • radioactive for longer
  • emit slowly
  • exposure is less harmful
30
Q

Describe 4 uses of nuclear radiation

A

MEDICAL TRACERS

  • isotope ingested or injected in to body
  • can be detected from outside as it travels around body

MONITORING KIDNEY FUNCTION

  • isotope used that’ll pass through kidneys
  • if it builds upon one kidney but not another, one kidney isn’t working efficiently

INTESTINE BLOCKAGES

  • blockage = radioactivity can’t be detected after blockage
  • damage = radioactive source can be seen passing out of kidneys to other parts of body where it shouldn’t

TUMOURS

  • focussed beam of gamma rays
  • radioactive iodine for thyroid rumours, gathers in the gland and destroys cells
31
Q

When choosing an isotope for medical use, what should be considered?

A

half life (needs to be long enough to perform task but not too long that it stays radioactive in patient for a long time) , activity, type of radiation

32
Q

Why are gamma rays best for tracers

A
  • penetrates the body
  • can be detected from outside
  • least ionising
33
Q

What are the components of background radiation?

A
  • radon gas
  • medical (x-rays)
  • nuclear
  • cosmic rays
  • gamma
  • food
    13% man made
    87% natural
34
Q

What does someone’s exposure to background radiation depend on?

A
  • location (some places have higher natural background radiation)
  • occupation (some jobs are exposed to radiation daily)
35
Q

Define nuclear fission and how it occurs

A
  • splitting if a large unstable nucleus (uranium or plutonium)
  • needs to absorb a neutron (won’t occur on its own)
  • absorbs a neutron
  • splits into two equal nuclei
  • emits: 2/3 neutrons, gamma rays, energy
  • all products have kinetic energy
  • chain reaction
36
Q

What are the uses of nuclear fission?

A
  • nuclear reactors ( chain reaction is controlled for constant steady energy release)
  • explosions in nuclear weapons are uncontrolled chain reactions
37
Q

Describe nuclear fusion

A
  • opposite of fission
  • two light nuclei join to form a heavier nucleus
  • some of the mass is converted in to energy which may be emitted as radiation
38
Q

Why does nuclear fusion require high temperatures and pressures?

A
  • overcome electrostatic repulsion

- bring positive nuclei close enough for fusion to occur

39
Q

How is alpha decay represented in nuclear equations?

A

4
2 He

  • mass number -4
  • atom number -2
40
Q

How is beta decay represented in nuclear equations?

A

0
-1 e

  • mass number doesn’t change
  • atomic number +1

GCSE Physics (11 decks)

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