P6

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  • Created by: zoe
  • Created on: 16-03-14 14:49
What element doesn't have any neutrons?
hydrogen
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What are they called when some atoms of the same element can have different numbers of neutrons?
isotopes
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What are the three types of ionising radiation?
Alpha, Beta, Gamma
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How far is alpha absorbed?
a few centimeters of air or a thin sheet of paper
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How far is Beta absorbed?
passes through air and paper but is absorbed by a few meters of aluminium
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How far is gamma absorbed?
very penetrating and needs many centimeters of lead or many meters of concrete to absorb most of it
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What is emmited when the nucleus of an unstable atom decays?
ionising radiation
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What does the type of radioactive decay depend on?
why the nucleus is unstable
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What happens during alpha decay?
original atom decays by ejecting helium alpha particle from nucleus, made from 2 protons & neutrons, a new atom is formed with 2 less protons & neutrons than the original
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What happens during beta decay?
original atom decays by changing a neutron into a electron and proton, high energy electron now ejected from nucleus as a beta particle, a new atom is formed with one less proton and neutron than the original
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What happens during gamma decay?
after alpha or beta, a nucleus sometimes contains surplus energy, it emits this as gamma radiation, only energy is emitted, doesn't change the type of atom
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What does it mean when a person is irradiated?
they're exposed to radiation
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What does it mean when a person is contaminated?
radioactive material is on their skin, clothes, or has entered their body
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What is the half life of a substance?
the time it takes for its radioactivity to halve
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When is a radioactive substance considered safe?
when its activity drops to the same level as background radiation
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What is considered a safe amount of radiation?
3 millisieverts a year
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What is the sievert?
the measure of a radiation dose's potential harm to a person
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Why is alpha the most dangerous inside the body?
all the radiation will be absorbed by cells in the body
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Why is beta the most dangerous outside the body?
it can penetrate the outer layer of skin and damage internal organs
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How can gamma cause harm?
absorbed into cells, weakly ionising and can pass straight through the body causing no damage at all
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What can radiation be useful for?
killing cancer cells, sterilising surgical instruments and food, as a tracer in the body
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How does a PET scan work?
radio-labelled glucose put in blood stream, gamma rays let out and picked up to create body image
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What is high-level waste? (HLW)
very radioactive waste that has to be stored carefully
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What is intermediate-level waste? (ILW)
not as radioactive as HLW but remains reactive for thousands of years, mixed with concrete and stored in containers
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What is low-level waste? (LLW)
only slightly radioactive waste that is sealed and placed in landfills
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Where does nuclear fission take place?
in the nucleus of the atom
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What are formed during nuclear fission?
new elements
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How does nucleur fission work?
nutron absorbed by large and unstable uranium nucleus, splits in 2, releases energy and more neutrons,
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What does nuclear fission cause to happen?
chain reaction
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What controls the chain reaction so that energy is steadily released in a nuclear power station?
nuclear reactor
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What three observations were made in the alpha particle scattering experiment?
most alpha particles were seen to pass straight through the gold foil, some particles were deflected slightly, a few particles bounced back towards the source
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What 3 conclusions were made in the alpha particle scattering experiment?
atoms consist largely of empty space with a small dense core-the nucleus, the nucleus is positively charged, the electrons are arranged around the nucleus with lots of space between them
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What does the strong nuclear force within a nuceus balance?
the repulsive electrostatic force between the protons
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Other cards in this set

Card 2

Front

What are they called when some atoms of the same element can have different numbers of neutrons?

Back

isotopes

Card 3

Front

What are the three types of ionising radiation?

Back

Preview of the front of card 3

Card 4

Front

How far is alpha absorbed?

Back

Preview of the front of card 4

Card 5

Front

How far is Beta absorbed?

Back

Preview of the front of card 5
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