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

25
Where does nuclear fusion comenly occour
In stars. Mostly hydren nuclei fusing to produce Helium
26
What is nuclear fission
When a large unstable nucleus absourbed a neutron and splits into 2. This releases Engery and usually neutrons
27
What is the process of Nuclear fission and the chain reaction that can occour
- 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
How can you limit the amount of energy produced in nuclear fission
By slowing down or absourbing the neutrons you can control the amount of energy prodcued and the length of the chain reaction
29
What is used in nuclear reactors to control nuclear fission
- Control rods which absourb excess neutrons (boron) - Moderators to slow down the neutrons usually water or graphite
30
What is activity (refering to isotopes)
The overal rate of decay in a group of radioactive decay
31
What is decay mesured in
Becquerels 1 Bq = 1 decay per second
32
Define Half lives
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
How do you determine the half life of a material from a graph
Across where the activity has halved and down to the time it takes for one half life to occour
34