Chapter 6 - Radioactivity Flashcards

1
Q

What are the three types of radiation emitted

A
  • Alpha radiation
  • Beta radiation
  • Gamma radiation
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2
Q

Can you tell when an unstable nucleus will decay?

A

You cannot predict when an unstable nucleus will decay. It is a random process and is not affected by external conditions

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3
Q

What is background radiation

A

Radiation from radioactive substances in the environment, from space, from devices such as x-Ray tubes

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4
Q

What was the alpha particle scattering experiment

A

Where alpha particles were fired at thin gold foil

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5
Q

Why did most of the atom particles pass through through the foil

A

Because most of the atom is just empty space

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6
Q

Why did some of the alpha particles become deflected through small angles

A

Because the nucleus has a positive charge so some of the alpha particles rebound as they must be repelled by another positive charge

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7
Q

Why would a few alpha particles rebound through very large angles

A

If the nucleus has a large mass and a very large positive charge

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8
Q

What happens in alpha decay

A

The nucleus loses 2 protons and 2 neutrons and are emitted as an alpha particle

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9
Q

What happens in beta decay

A

A neutron in the nucleus changed into a proton and electron and the electron created is instantly emitted

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10
Q

What are the issues with ionisation

A

It kills or damages living cells

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11
Q

What is half life used for

A

To measure how quickly the radioactivity decreases.

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12
Q

How do the nuclei of radioactive substances become stable

A

By radioactive decay. In this process they emit radiation and turn into other elements

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13
Q

What is an isotope

A

Atoms of same element with different numbers of neutrons

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14
Q

What does an alpha particle consist of

A

2 protons and 2 neutrons. It has a relative mass of 4 and its relative charge is 2+

It is represented as 4 a
2

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15
Q

What is a beta particle and what does it consist of

A

A high speed electron from the nucleus, emitted when a neutron in the nucleus changes to a proton and electron. It’s relative mass is 0 and its relative charge is -1

It is represented as 0 B
-1

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16
Q

Does gamma ray have a charge or mass

A

No because a gamma ray is an electromagnetic wave released from the nucleus

17
Q

Why does ionisation occur

A

When nuclear radiation travels through a material it will collide with the atoms of the material. This knocks electrons off them, creating ions.

18
Q

How ionising are alpha particles

A

Strongly ionising because they are relatively large so they have lots of collisions - because of these collisions they do no not penetrate far into the material

19
Q

How can alpha particles be stopped

A

By a thin sheet of paper, human skin or few centimetres of air

20
Q

How ionising are beta particles

A

Less ionising than alpha particles as they are much smaller and faster. They can penetrate further

21
Q

How are beta particles blocked

A

By a few metres of air of thin sheet of aluminium

22
Q

How ionising are gamma rays

A

Weakly ionising but very penetrating. Not deflected by electric and magnetic fields like alpha particles and beta particles

23
Q

Where are alpha sources used

A

In smoke alarms

24
Q

What are beta sources used for

A

Thickness monitoring in manufacturing things like paper or metal foil.

25
What are gamma and beta sources used as
As tracers in medicine. Source is injected or swallowed be patient. Progress around body monitored by detector outside patient
26
What is radioactive dating used for
To find the age of ancient material.