Radioactivity

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What is Ionisation?
When an atom loses or gains one or more electron. This causes radioactivity and gives of ionising radiation.
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What happens when an atom loses an electron?
It becomes a positive ion.
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What happens when an atom gains an electron?
It becomes a negative ion.
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What is the atomic number?
The number of protons in the nucleus of an atom. Found at the bottom of the element symbol.
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What is the atomic mass number?
The total number of protons and neutrons (nucleons) of an atom. Found at the top of an element symbol.
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What is an isotope?
An atom of the same element with a different atomic mass number.
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What charge do protons have?
Protons have positive electrical charge. (+1)
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Where are protons found?
In the nucleus.
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What mass do protons have?
1
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What charge do neutrons have?
Neutrons have no charge. (0)
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Where are neutrons found?
In the nucleus.
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What mass do neutrons have?
1
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What charge do electrons have?
They have a negative electrical charge. (-1)
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Where are electrons found?
Orbiting the nucleus inside an atom due to the electrostatic attraction between the electrons and protons.
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What mass do electrons have?
0.005
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What are the 3 types of radiation?
Alpha, Beta and Gamma.
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What is an alpha particle?
2 protons and 3 neutrons.
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What is a beta particle?
A high speed electron. It is made when a neutron splits to form a proton and an electron.
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What are gamma rays?
Very high frequency electromagnetic waves produced when an unstable nucleus loses energy.
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What charge do alpha particles have?
+2
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What do alpha particles like to become?
They grab electrons from the surroundings to become helium atoms.
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What can stop alpha particles?
A few cm of air or a sheet of paper.
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What can stop beta particles?
1cm of aluminium or 1m of air.
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What stops gamma rays?
Several cm of lead or 1m of concrete.
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What attracts alpha particles?
A negative electric field.
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What attracts beta particles?
A positive electric field.
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What is the plum pudding atomic model?
A suggestion of what an atom was, eg. positively charged matter embedded with negatively charged electrons.
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In the gold foil experiment, why were some alpha particles deflected?
Because as the positive alpha particles were repelled by the positive gold nucleuses.
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According to Rutherford, what do atoms consist of?
A tiny, positively charged nucleus surrounded by a cloud of negative electrons.
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What is the mass number of an alpha particles?
4
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What is the mass number of a beta particle?
0
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How can you detect radioactivity?
You can use a Geiger counter or wear a photographic film badge.
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What is 1 becquerel equal to?
1 decay per second
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What is Nuclear Fission?
The splitting of an atomic nucleus.
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What does Nuclear Fission produce?
Slow moving electrons, gamma rays, 2 daughter nuclei and kinetic energy.
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Where is Nuclear Fission used?
To create energy in nuclear power stations.
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What is the purpose of a moderator in a nuclear power station?
It slows down the neutrons so they can be absorbed by running them through water.
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What is background radiation?
Low level ionising radiation ionising radiation that is produced all the time.
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Where does background radiation come from?
Radon Gas, Cosmic Rays, food and drink, medical materials, rocks, air, nuclear weapons, air travel and nuclear reactors.
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What is half-life?
The time is takes for 1/2 of the original mass to decay.
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What is the half-life of Carbon 14?
5600 years
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What can radioactive substances be used for?
Carbon dating, Medical tracers, leaks in underground systems, smoke detectors and automatic thickness monitoring.
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How does Carbon dating work?
It is used to find the age of ancient materials as living wood has a tiny proportion of radioactive C-14.
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How do medical tracers work?
They follow the flow of the substance through the body to detect blockages and problems in the digestive system. They normally use substances with short half-lives so the patients aren't harmed.
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How do using radioactive substances for leaks in underground systems work?
Radioactive tracers added to fluids, when there is a leak there will be a higher count rate on the Geigner counter. Beta radiation is normally used as it can be detected more easily.
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How do smoke detectors work?
A radioactive source inside the alarm ionises a small portion of air so it conducts electricity. Smoke prevents the radiation
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How does automatic thickness monitoring work?
It sends beta radiation as it has a long half-life through to automatically adjust the rollers in closer or apart.
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Other cards in this set

Card 2

Front

What happens when an atom loses an electron?

Back

It becomes a positive ion.

Card 3

Front

What happens when an atom gains an electron?

Back

Preview of the front of card 3

Card 4

Front

What is the atomic number?

Back

Preview of the front of card 4

Card 5

Front

What is the atomic mass number?

Back

Preview of the front of card 5
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