Radioactivity

Why are some elements radioactive?
Because their nuclei are unstable.
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What happens when elements have unstable nuclei?
They will go through radioactive decay and change into other elements. This happens when alpha, beta, gamma or neutron radiation is emitted.
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Can you determine exactly when any nucleus will decay next?
You can't because the process is random.
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What is an alpha particle made up from?
It is a helium nucleus. It is composed of two protons and two neutrons. It has a charge of +2 and is the heaviest of the particles emitted by unstable atoms.
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What is a beta particle made up from?
It is an electron. It has a charge of -1.
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What is a gamma ray?
A form of high-energy electromagnetic radiation. It has no mass or charge.
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How do alpha, beta and gamma rays ionise atoms?
By colliding with them which causes them to lose electrons.
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How far will Alpha particles travel in the air?
5cm in air
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How ionsing are Alpha particles?
Very ionising
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What can Alpha particles be stopped by?
A sheet of paper
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How far will beta particles travel in air?
A few metres in air
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How ionising are beta particles?
Moderately ionising
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What can beta particles be stopped by?
Aluminium 3mm thick
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How far will gamma rays travel in air?
A few kilometers
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How ionising are gamma rays?
Weakly ionising
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What can gamma rays be stopped by?
Thick lead
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Can alpha particles be affected by magnetic fields?
Yes
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Can beta particles be affected by magnetic fields?
Yes but in the opposite direction to Alpha particles
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Can gamma rays be affacted by magnetic fields?
No because they aren't charged
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What is background radiation?
Radiation that comes from natural sources
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What is radon?
A gas that is produced when uranium in rocks decays. Radon decays by emitting an alpha particle.
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Name 6 different sources of backgrund radiation
Radon gas, ground and buildings, medical, nuclear power, cosmic rays (from space) and food and drink.
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What are two ways you can measure and detect radiation?
Photographic Film and Geiger-Muller Tube
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What is a Geiger-Muller Tube?
It's used to detect nuclear radiation. It is connected to a counter or ratemeter which shows the amount of radiation that has been detected.
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What does a Geiger-Muller Tube contain and what does it do?
Argon gas so that argon atoms are ionised by the radiation when it enters. A thin wire connected to a voltage of above 400v. Electrons travel down the thin wire and then more elctrons are knocked from atoms which creates an avalanche effect.
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In 1896 what did Henri Becquerel discover?
That uranium slats could lead to the darkening of photographic film, even if it was wrapped up so that no light could reach it.
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How is photographic film darkened by the uranium salts?
Radiation was being emitted from the uranium nuclei which darkened the film.
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What could beta decay be used for?
It can be used for radiocarbon dating which involves finding the ages of materials that are thousands of years old.
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What changes occur in the nucleus of an atom when it emits alpha radiation?
It's nuclear mass reduces by 4 and its positive charge reduces by 2
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What cahnged occur in the nucleus of an atom when it emits beta minus decay?
The mass stays the same but its charge is increased by 1
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What is that activity of a radioactive source?
The number of atoms that decay every second
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What is the half life of a radiactive substance?
The time it takes for half of the unstable atoms to decay. This is also the time for the activity to go down by half.
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Why is ionising radiation dangerous to humans?
It can knock electrons out of atoms to form ions. Ions are very reactive and can cause mutations to the DNA in cells. This can lead to cancer. It can also cause damage to cell tissue in the form of radiation burns. It could kill cells.
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What three things can help protect a person from ionising radiation?
Limiting the time of exposure, wearing protective clothing and increasing the distance bwteen the person and the radioactive source
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Why does wearing protective clothing around a radioactive source help protect you from ionising radiation?
Wearing a lead apron will absorb much of the ionising radiation
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What is irradiation?
Ionising radiation from an external radioactive source travelling to the body. It is not breathed in, eaten or drank and the source doesnt come into contact with the skin.
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What could irradiation be in the form of?
Harmful gamma rays, beta particles and x-rays.
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What is external contamination?
When a radioactive material comes into contact with a persons hair, skin or clothing.
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What is internal contamination?
When a radioactive source is eaten or drank.
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What type of contamination would being exposed to cosmic rays from the sun be?
Irradiation
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What type of contamination would having an X-ray be?
Irradiation
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What type of contamination would radiactibe dust coming into contact with your skin be?
External contamination
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What is contamination?
When a radioactive source comes into contact with the skin or is taken into the body
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Other cards in this set

Card 2

Front

What happens when elements have unstable nuclei?

Back

They will go through radioactive decay and change into other elements. This happens when alpha, beta, gamma or neutron radiation is emitted.

Card 3

Front

Can you determine exactly when any nucleus will decay next?

Back

Preview of the front of card 3

Card 4

Front

What is an alpha particle made up from?

Back

Preview of the front of card 4

Card 5

Front

What is a beta particle made up from?

Back

Preview of the front of card 5
View more cards

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