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additional physics > Topic 5 > Flashcards

Topic 5 Flashcards

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1
Q

Where does all radioactivity come from

A

Unstable reactive isotopes undergoing nuclear decay and spitting out high-energy particles or waves

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2
Q

What is given of when unstable nuclei decay

A

Ionising radiation

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3
Q

Radioactivity is a ……..process

A

Random

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4
Q

When the nucleus does decay it will give out one or more of the three types of ionising radiation
In the process what happens

A

It will change into a new element

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5
Q

What is ionisation

A

When an atom loses or gains an electron becoming an ion

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6
Q

Alpha beta gamma cause

A

Ionisation of atoms

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7
Q

What do radioactive isotopes do

A

Decay into other elements and give out radiation

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8
Q

Alpha particles have a large ……. Charge

A

Positive

Therefore pull negatively charged electrons out of atoms orbit

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9
Q

Beta particles are …….. Charged

A

Negatively

Put electrons out of atoms orbit beeping them

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10
Q

How do gamma rays cause ionisation

A

They interact with electrons orbiting atom transferring energy to them
If election gets enough energy it can break free from atom

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11
Q

The more ionising the radiation is

A

The less penetrating it is

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12
Q

Why is more ionising radiation less penetrating

A

Because it gives up its energy quickly as it creates ions

Don’t penetrate far

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13
Q

Alpha particles travel at a …….. Speed

A

Slow

Increasing chance of radiation

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14
Q

Alpha particles are ……..nuclei

A

Helium nuclei

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15
Q

How many protons and neutrons does Apha particles, helium nuclei have

A

Two protons

Two neutrons

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16
Q

What kind of charge do Apha particles have

A

Strong positive charge

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17
Q

Name three factors of Apha particles

A

Big
Heavy
Slow moving

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18
Q

Apha particles big mass and charge make them

A

Strongly ionising
Remove electrons from lots of atoms, creating lots of ions
Don’t penetrate far into materials, stopped quickly

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19
Q

Beta particles are……

A

Electrons emitted from nucleus

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20
Q

Beta particles move…….

And are quite…….

A

Fast

Small (electrons)

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21
Q

Beta particles are……..charges

A

Negatively

Are electrons

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22
Q

Deceive the ionising and penetrating properties of beta particles

A

Moderately ionising

Penetrate moderately far into materials before being stopped

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23
Q

For every beta particle emitted

A

A neutron turns into a proton in the nucleus

24
Q

Gamma rays are a type of

A

Electromagnetic radiation

25
Q

Gamma rays are opposite to

A

Gamma particles

26
Q

Name properties of gamma rays

A

Weakly ionising and can penetrate a long way into materials before interacting with an atom

27
Q

What are alpha particles blocked by

A

Paper and cardboard

28
Q

What are beta particles blocked by

A

Aluminium

29
Q

What are gamma rays blocked by

A

Thick lead

30
Q

Nuclear fission is

A

A type of nuclear reaction that is used to release energy from uranium(or plutonium atoms.
E.g nuclear reactor
Huge amounts of energy released using chain reaction

31
Q

Describe how an atom becomes unstable and splits up

A

Slow-moving neutron is fired at an isotope of uranium (-235)

Neutron is absorbed by nucleus causing atom to become unstable and split

32
Q

When uranium -235 splits what does it form

A

Two new lighter elements (‘daughter nuclei’)

Thermal (heat) energy is released

33
Q

Why is a neutron absorbed by the nucleus

A

Because it has no charge

(Not repelled by opposite charge of nucleus

34
Q

Name two nuclei that uranium-235 split into

A

Krypton-91

Barium-143

35
Q

Why are the new nuclei of uranium-235 radioactive

A

They have the ‘wrong’ number of neutrons in them

36
Q

How is the chain reaction repeated

A

When uranium splits up it produces two or three new neutrons which hit another uranium nuclei causing them to split up.
And so on…

37
Q

What are nuclear power stations powered by

A

Nuclear reactors where a controlled chain reaction takes place splitting up uranium
Heat energy produced form nuclear fission is used to boil water to drive steam turbine, which turns a generator to generate electrical energy.

38
Q

Chain reactions must be

A

Carefully controlled

39
Q

The neutrons released by fission reactions in nuclear reactors have

A

Lots of energy

40
Q

When will these released neutrons cause another nuclear fission

A

Is they are moving slow enough to be captured by the uranium nuclei in fuel rods

41
Q

What are placed in a generator to slow down fast moving neutrons

A

Uranium fuel rods

42
Q

What effect does uranium fuel rods hVe in a moderator

A

Creates steady rate of nuclear fission

One new neutron produces another fission

43
Q

What are control rods often made of and what do they do

A

Boron

Limit rate of fission by absorbing excess neutrons

44
Q

Where are boron control rods placed

A

Between fuel rods and raised and lowered into the reactor to control the chain reaction

45
Q

What happens if the chain reaction in the nuclear reactor is left to continue unchecked

A

Large amounts of energy released over short time

Many fissions follow each other leading to runway reaction which can cause explosion.

46
Q

What happens in nuclear fusion and give an example

A

Two light nuclei collide at high speed and join (fuse) to create larger nucleus
E.g hydrogen nuclei fuse to produce helium nuclei

47
Q

What does fusion give of a lot of and is it more or less than fission

A

Energy and more than fission

48
Q

Energy from stars comes from fission so what are trying to be developed

A

Fusion reactors to make electricity

49
Q

What it a positive of fusion and why would it be good for making electricity

A

Doesn’t leave behind much radioactive waste

Plenty of hydrogen to use as fuel

50
Q

What is a problem with fusion

A

Only happens at high temp and pressures

Not at low due to electrostatic repulsion of protons

51
Q

What are the problems of making fusion reactors

A

Hard to create right conditions for fusion
No material withstands heat and pressure (just vaporise)
Therefor hard no expensive to build

52
Q

What does hydrogen need to be stored in for fusion reactors

A

Magnetic field instead of physical container

53
Q

Why are the few experimental fusion reactors not generating electricity

A

It takes more electricity to get up to the temperature then the reactor can produce

54
Q

What is a theory that hasn’t been accepted yet

A

‘Cold fusion’

Nuclear fusion with accrues at room temperature rather than millions of degrees C

55
Q

What would be advantages of cold fusion

A

Generate lots of electricity, easily and cheaply

56
Q

What two scientists believed they had discovered cold fusion

A

Stanley Pons

Martin Fleischmann

additional physics (4 decks)

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