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Physics 💡 > 4. Atomic Structure > Flashcards

4. Atomic Structure Flashcards

(49 cards)

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1
Q

How large is an atom?

A

It has a radius of 1 x 10 to the -10 metres.

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2
Q

How large is the radius of the nucleus of an atom?

A

1/10000 of the atom

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3
Q

What happens in the alpha particle experiment?

A
  • most of the particles pass straight through
  • so most of the atom is empty space
  • a few alpha particles deflected through large angles
  • so mass is concentrated at the centre of the atom
  • and the nucleus is positively charged
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4
Q

What is the order of the scientists in the discovery of the atom?

A

John Dalton, JJ Thomson, Ernest Rutherford, Niels Bohr, James Chadwick

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5
Q

What did John Dalton discover?

A

In 1803, he thought all matter was made up of atoms (tiny spheres).

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6
Q

What did JJ Thomson discover?

A

He discovered electrons and made the idea of the plum pudding model. (The atom is a ball of positive charge with negative electrons embedded, mass is evenly distributed)

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7
Q

What did Ernest Rutherford discover?

A

He discovered the nucleus and proton through the alpha particle experiment, proving the nuclear model.

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8
Q

What did Niels Bohr discover?

A

He discovered that electrons orbit the nucleus at specific distances through calculations. Positive charges were identified and named protons.

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9
Q

What did James Chadwick discover?

A

He found evidence for the neutron and that it is found in the nucleus.

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10
Q

What is the order of discovery of the subatomic particles?

A

Electrons, protons, neutrons.

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11
Q

How does an alpha, gamma or beta particles become stable?

A

The unstable nuclei emits a particle (we say the atom has decayed)

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12
Q

What is some information about alpha, beta and gamma decay?

A

It is said to be random and cannot be affected by temp/ pressure etc.

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13
Q

What is the amount of radioactivity given out measured in?

A

Becquerels (Bq) (one becquerel is one particle emitted per second)

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14
Q

What is the composition of alpha radiation?

A

2 protons, 2 neutrons

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15
Q

What is the charge of alpha radiation?

A

+2

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16
Q

What is alpha radiation stopped by?

A

Paper

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17
Q

What is the range in air of alpha radiation?

A

Less than 5cm

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18
Q

What is the ionising power of alpha radiation?

A

It is highly ionising.

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19
Q

What is the composition of beta radiation?

A

1 electron from the nucleus (high speed, high energy)

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20
Q

What is the charge of beta radiation?

21
Q

What is beta radiation stopped by?

Study These Flashcards
A

It can travel through skin and tissue but is stopped by 3mm aluminium foil.

22
Q

What is the range of beta radiation in air?

Study These Flashcards
A

Approximately 1m

23
Q

What is the ionising power of beta radiation?

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A

Ionising (middle power)

24
Q

What is the composition of gamma radiation?

Study These Flashcards
A

It is an electromagnetic wave

25
What is the charge of gamma radiation?
No charge
26
What is gamma radiation stopped by?
It is stopped by lead/ concrete.
27
What is the range in air of gamma radiation?
Over 1km
28
What is the ionising power of gamma radiation?
Very low.
29
How does beta decay work?
In the nucleus, a neutron changes into an electron (the beta particle) and a proton in the nucleus. The mass number stays the same BUT the proton number increases by 1.
30
How can neutrons be emitted by radioactive particles?
An alpha particle collides with unstable nuclei in the substance causing the unstable nuclei to emit a neutron.
31
What happens when calculating alpha decay?
The mass number increases and the proton number decreases.
32
What happens when calculating beta decay?
The mass number stays the same and the proton number decreases by 1.
33
What is the half life of a substance?
The average time it takes for half of the number of nuclei in a sample to decay OR for the radioactivity of a substance to decrease by half.
34
What is nuclear fission?
A process that uses the SPLITTING of atoms/ nuclei to generate vast amounts of energy.
35
What are the stages of nuclear fission?
- a slow neutron moves towards the nucleus - the neutron is absorbed by the nucleus making it unstable - it starts to oscillate - the nucleus splits into 2 pieces and 3 neutrons releasing energy - the neutrons may start more fission - then a chain reaction occurs
36
What are the advantages of nuclear fission?
- most fuel is cheap - gives out lots of energy per kg - no greenhouse gases or carbon dioxide released - more reliable than renewable resources
37
What are the disadvantages of nuclear fission?
- the overall cost is high - waste process and decommissioning takes time - waste needs to be buried at controlled sites - waste can be very hot and needs to be stored for 50 years in lead lines containers before decomposed
38
What is nuclear fusion?
The joining of 2 light nuclei to form a heavier nucleus. In this process, some of the mass may be converted into energy of radiation.
39
What happens if the temperature is not height enough for nuclear fission?
The particles will collide off of each other due to electrostatic repulsion.
40
What are the advantages of nuclear fusion?
- less radioactive waste - no weapons material produced - small amounts of fuel needed - abundant fuels - safe - no greenhouse gases or polluting gases made
41
What is the energy of an electron closer to the nucleus?
It is lower
42
What is the energy of an electron further away from the nucleus?
It is higher
43
Where is radiation from?
Radon gas from the ground, food and drink, cosmic rays, medical uses + gamma rays from the ground and buildings
44
What is radiation does measured in?
Sieverts (Sv)
45
What is radioactive contamination?
The unwanted presence of materials containing radioactive atoms on other materials. The hazard from contamination is due to the decay of contaminating atoms. The type of radiation emitted affects the level of hazard.
46
What is irradiation?
The process of exposing an object to nuclear radiation. The irradiated object does NOT become radioactive.
47
How can we reduce risks using radioactive sources?
- keep radioactive sources shielded (in a lead lined box) when not in use - wear protective clothing - avoid contact with bare skin - do not attempt to taste sources - wear face masks - limit exposure time - use tongs - monitor exposure using detector badges
48
What are some uses of radiation?
- isotopes can be used as medical and industrial tracers - use of isotopes with a short half life can limit exposure - imaging processes can replace some invasive surgical procedures
49
What are some disadvantages of contamination?
- radioactive isotopes may not go where they are wanted - difficult to ensure contamination is fully removed- sometimes small amounts of isotope are left behind - damage potential to healthy cells

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