P7 Atomic Structure Flashcards

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1
Q

What is the entire history of the atom

A

Atoms thought to be tiny undividable spheres
Discovery of electron led to plum pudding model
Alpha particle scattering experiment led to the discovery of nuceus, nuclear model replaced plum pudding
Niels Bohr suggested electrons orbit the nucleus in specific shells
Proton was later discovered after it was suggested that the positive charge of nucleus could be seperated into subatomic particles
James Chadwick provided evidence of neutrons

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2
Q

What is radioactive decay

A

When an unstable nuclei gives out radiation as it changes to become more stable

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3
Q

What is activity and what is it measured in

A

The rate at which a source of unstable nuclei decays

Measured in Becquerels ( Bq )

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4
Q

What is count rate

A

The number of decays recorded each second by a detector ( eg geiger - muller tube )

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5
Q

What are the compositions of: an alpha particle, a beta particle, a gamma ray

A

Alpha particle: 2 neutrons and 2 protons
Beta particle: a high speed electron efected from the nucleus as a neutron turns into a proton
Gamma ray: electromagnetic radiation from the nucleus

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6
Q

What are alpha, beta and gamma stopped by

A

Alpha: 5cm of air or thin paper
Beta: thin aluminium
Gamma: thick lead or thick concrete

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7
Q

What are the range in air of alpha, beta and gamma

A

Alpha: 5cm
Beta: 1m
Gamma: unlimited

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8
Q

What is the ionising power of alpha, beta and gamma

A

Alpha: most
Beta: medium
Gamma: least

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9
Q

What is the equation for alpha decay

A

A A-4 4
X = D + α
Z Z-2 2

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10
Q

What is the equation for beta decay

A

A. A. 0
X = D + B
Z. Z+1. -1

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11
Q

What is the halflife of a radioactive isotope

A

The time it takes for the number of radioactive nuclei of the isotope in a sample to halve, or the time it takes for the count rate (or activity) from a sample containing the isotope to fall to half its initial level

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12
Q

What is radioactive contamination

A

The unwanted presence of materials containing radioactive atoms on other materials

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13
Q

What is irradiation

A

Irradiation is the process of exposing an object to nuclear radiation. The irradiated object does not become radioactive

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14
Q

What are some examples of background radiation

A

natural sources such as rocks and cosmic rays from space
man-made sources such as the fallout from nuclear weapons
testing and nuclear accidents.

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