5. Atomic Physics Flashcards

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1
Q

Describe the nucleus of a radioactive atom

A

Most atoms each have a stable nucleus that doesn’t change
Atoms of a radioactive substance each have a nucleus that is unstable
They becomes stable by emitting alpha, beta or gamma radiation

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2
Q

Describe alpha radiation

A
2 protons and 2 neutrons
Charge: +2
Mass: 4
Ionizing: strong
Penetration: not penetrating, stopped by paper
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3
Q

Describe beta radiation

A
1 high energy electron
Charge: -1
Mass: 1/2000
Ionizing: moderate
Penetrating, stopped by aluminium
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4
Q

Describe gamma radiation

A

It is electromagnetic wave -> electromagnetic radiation
Charge = 0
Mass = 0
Ionizing: weak
Very penetrating, only stopped by thick lead or concrete

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5
Q

What is ionization

A

Radiation from radioactive substances knocks electrons out of atoms and the atoms become charged

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6
Q

Describe alpha, beta and gamma deflection in electric fields

A

Gamma radiation is electrically neutral -> alpha and beta radiation can be deflected by the electric fields but gamma is not
Alpha particles are positively charged -> attract towards a negatively charged plate
Beta particles are negatively charged -> attract towards a positively charged plate

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7
Q

Describe background radiation

A

Ionising radiation that is constantly present in our natural surroundings
Some come from natural sources: air, ground, cosmic
Some come from artificial sources: medical, food&drink, air travel, nuclear weapons

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8
Q

Describe alpha, beta and gamma deflection in magnetic field

A

Beta radiation is easily deflected
Alpha radiation is deflected in the opposite direction to beta radiation bc they have opposite charges
Beta radiation is harder to deflect than alpha radiation bc it has much more mass -> more force to change its direction of motion
Gamma radiation is not deflected by a magnetic field

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9
Q

Compare the ionization of alpha, beta and gamma radiation and suggest reason

A

Alpha > beta
Bc alpha particle has much more mass than beta particle and moves more slowly -> has much more effect on the atoms it encounters
Beta > Gamma
Bc beta particles are charged whereas gamma radiation is uncharged

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10
Q

What is decay?

A

When an unstable nucleus emits radiation

Radioactive is a random event and cannot be predict or influence when it will happem

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11
Q

Describe the decay of alpha, beta and gamma

A

Alpha radiation is released in the form of a helium atom
Beta is releases in the form of an electron
Gamma radiation: energy is released

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12
Q

Define half life

A

The time taken for half the nuclei to decay

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13
Q

What are some safety precaution when using radioactive substances

A

Wear protective clothing - gloves, lab coat, safety glasses
Radioactive stuff is stored in a lead container, in s locked cabinet
Picked up with tongs
Kept away from body, not pointed at ppl
Left out of its container for as short a time as possible

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14
Q

Define isotope

A

Atoms of the same element with the same number of protons but with different number of neutrons

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