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Physics > P6- Radioactivity > Flashcards

P6- Radioactivity Flashcards

1
Q

What is an isotope

A

An atom with a different number of neutrons

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2
Q

What happens to unstable isotopes

A

They undergo radioactive decay

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3
Q

Define a radioactive material

A

A material that consists of unstable isotopes that can decay

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4
Q

What are the 3 types of radiation

A
  • Alpha
  • Beta
  • Gamma
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5
Q

What is an alpha particle

A

A helium nucleus
- 2 protons
- 2 neutrons

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6
Q

What is the charge of an alpha particle

A

2+
(they have no electrons)

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7
Q

How is an alpha particle writen

A

4
He
2

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8
Q

How far can alpha particles travel

A

A few cm in air

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9
Q

What can absourb alpha radiation and why

A

A piece of paper.
Because alpha particles are relatively large.

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10
Q

How ionising is alpha radiation

A

Strongly ionising
- large 2+ charge
- can knock electrons off atoms easily

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11
Q

What is a beta particle

A

An electron

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12
Q

How do you write a beta particle

A

0
e
-1

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13
Q

How is beta radiation emitted

A

An atoms neutron decays into a proton and an electron, the electron is emitted at high speeds from the nucleus.

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14
Q

How ionising is beta radiation

A

Moderately ionising
- 1- weaker charge
- cannot knock electrons easily

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15
Q

How far can beta radiation travel

A

Several meters of air

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16
Q

What can stop beta radiation

A

5mm of aluminium

17
Q

What is gamma radiation

A

Waves of electromagnetic radiation often emitted after alpha or beta radiation to remove extra energy

18
Q

What is nuclear fusion

A

Nuclear fusion is the fusing of two lighter nuclei to make a single heavier nucleus and a lot of energy is emitted in the form of electromagnetic radiation.

19
Q

Is mass always conserved

A

No mass is not always conserved. It is not in nuclear fusion

20
Q

What causes the release of engery in nuclear fusion

A

Some of the mass from the 2 starting nuclei is converted into large amounts of engery

21
Q

What are the benifits of nuclear fusion

A
  • No nuclear waste
  • Hydrogen fuel is easily available
22
Q

What circumstances must occour for nuclear fusion to happen

A

Extremely high tempuratures and pressure

23
Q

In nuclear fusion what form is energy released

A

Electromagnetic radiation

24
Q

What eqaution is used to work out energy released in nucear fusion

A

E=m x c^2

25
Q

Where does nuclear fusion comenly occour

A

In stars. Mostly hydren nuclei fusing to produce Helium

26
Q

What is nuclear fission

A

When a large unstable nucleus absourbed a neutron and splits into 2. This releases Engery and usually neutrons

27
Q

What is the process of Nuclear fission and the chain reaction that can occour

A
  • A neutron hits a nucleus
  • This makes the nucleus unstable so it decays
  • It decays into 2 smaller nuclei, some neutrons and engery
  • The realsed neutrons can then hit other nuclei and cause them to decay
  • This causes the chain reaction
28
Q

How can you limit the amount of energy produced in nuclear fission

A

By slowing down or absourbing the neutrons you can control the amount of energy prodcued and the length of the chain reaction

29
Q

What is used in nuclear reactors to control nuclear fission

A
  • Control rods which absourb excess neutrons (boron)
  • Moderators to slow down the neutrons usually water or graphite
30
Q

What is activity
(refering to isotopes)

A

The overal rate of decay in a group of radioactive decay

31
Q

What is decay mesured in

A

Becquerels
1 Bq = 1 decay per second

32
Q

Define Half lives

A

The time taken for the number of radioative nuclei to halve
OR
The time taken for the activity to halve.
Both definintions are perfectly corrolated

33
Q

How do you determine the half life of a material from a graph

A

Across where the activity has halved and down to the time it takes for one half life to occour

34
Q
A

Physics (11 decks)

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