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Physics > Atomic Structure > Flashcards

Atomic Structure Flashcards

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1
Q

Who proposed the Plum Pudding Model, and describe its structure - Atomic Structure

A

JJ Thomson proposed the atom was a ball of positive charge with negative electrons spaced throughout

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2
Q

Who performed the Alpha Particle experiment and when? - Atomic Structure

A

Ernest Rutherford in 1905

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3
Q

What was the Gold + alpha particle experiment? - Atomic Structure

A

Alpha particles were fired at thin gold sheeting. It was thought they would pass straight through. Some did, but others were deflected.

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4
Q

What conclusions were made from the alpha particle experiment? - Atomic Structure

A

That the deflections must have come from a concentrated area of positive charge (the nucleus) and that ones that passed through were as a result of an atom being made up of mostly empty space

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5
Q

How did Niels Bohr believe electrons were placed in Rutherford’s model? - Atomic Structure

A

He believed that electrons orbited the nucleus at different distances or energy levels.

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6
Q

How do energy levels change? - Atomic Structure

A

When atoms absorb energy (from EM waves), electrons can move up energy levels, moving further from the nucleus. Vice-Versa for emitting energy.

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7
Q

What is an ion? - Atomic Structure

A

An atom with different numbers of protons to electrons

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8
Q

What are isotopes? - Atomic Structure

A

Isotopes are forms of elements that have the same number of protons but different numbers of neutrons

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9
Q

How can an atom’s nucleus be unstable? - Atomic Structure

A

If a nucleus contains dangerously more neutrons than protons, the nucleus can become unstable

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10
Q

What is an alpha particle? - Atomic Structure

A

A Helium-4 nucleus

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11
Q

What is a beta particle? - Atomic Structure

A

A fast moving electron

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12
Q

What is gamma radiation and how does it work? - Atomic Structure

A

A substance may emit a gamma wave in order to drop to lower energy levels

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13
Q

Which type of radiation is the most ionising? - Atomic Structure

A

Alpha - most easily converts from neutral into a charged particle

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14
Q

What is the definition of half life? - Atomic Structure

A

The time taken for half a radioactive substance’s unstable nuclei to decay.

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15
Q

Does a substance’s radioactivity theoretically ever reach 0? - Atomic Structure

A

No. The total of unstable nuclei just continues halving over the period of many half lives

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16
Q

What is irradiation? - Atomic Structure

A

Exposing objects to beams of radiation, allowing them to become irradiated.

17
Q

Name 3 ways radiation can be positively used - Atomic Structure

A

Can be used to preserve fruit. Cobalt-60 kills bacteria on fruit when exposed, without damaging the fruit.
Can be used to destroy cancerous growths
Used to sterilise surgical instruments

18
Q

How does irradiation of cancer cells work? - Atomic Structure

A

Beams of gamma are fired at a specific point from different angles. Healthy cells receive low doses of gamma, whilst cancerous cells receive high doses.

19
Q

How can risks of dangerous irradiation be managed? - Atomic Structure

A

Keeping penetrative radioactive sources in lead lined boxes
Wearing protective clothing
Avoiding contact with skin
Monitor exposure using detectors

20
Q

What is the unit for Radiation? - Atomic Structure

A

Becquerels (Bq)

21
Q

Identify 4 causes of background radiation - Atomic Structure

A 
Cosmic rays
Food and drink
Radon gas from the ground
Nuclear power + weapons testing
Medical sources
Buildings + the ground
22
Q

What do Sieverts measure? - Atomic Structure

A

Measures a dose of radiation and the damage that does would cause

23
Q

Describe the process of nuclear fission - Atomic Structure

A

A neutron is fired at U-235. This causes the nucleus of the U-235 to split into 2 daughter nuclei + displacing neutrons. These neutrons impact other U-235 nuclei, releasing more energy. Chain reaction.

24
Q

What slows neutrons down in a fission reactor so that they can be absorbed by fuel rods? - Atomic Structure

A

A graphite core

25
Q

What is the role of control rods? - Atomic Structure

A

They can be raised and lowered to allow and prevent the travel of neutrons between fuel rods to alter a chain reaction’s speed

26
Q

What is nuclear fusion? - Atomic Structure

A

Where 2 small, light nuclei join together to create heavier nuclei and produce energy.

27
Q

What is required for nuclear fusion to take place? - Atomic Structure

A

High temperatures and high pressures

28
Q

Why is the fusion of nuclei difficult? - Atomic Structure

A

Because like charges repel, both nuclei are positive and therefore this must happen quickly to overcome the repulsion.

Physics (10 decks)

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