True of false, the number of protons are equal to the number of electrons.
True
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If an atom gains or loses an electron it will have an overall charge. This is known as what?
We say that the atom has been ionised
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When was atom first phased?
610BC
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Who invented the plum pudding model?
J.J. Thomson
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When was the plum pudding model invented?
1897
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What happened in 1909?
Rutheford and Marsden fired alpha particles through gold foil. Some defelcted back and so this lead to the nuclear model.
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What did Niels Borh do?
He tweaked the nuclear model and said the electrons are in fixed orbits.
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What is a photon?
A particle of light.
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What is the main source of background radiation?
Radon gas from the ground.
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What is the main properties of Alpha?
2 protons and 2 neutrons
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What are the main properties of beta minus?
Fast moving electrons. Ejected from the unstable nucleus when a neutron decays into a proton and electron.
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What are the main properties of beta positive?
The anti-electron (positron). Same properties as the electron except: forms when a proton decays into a neutron . Will annihilate when it comes into contact with an electron.
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What are the main properties of gamma?
A photon of EM radiation. It can also be considered to be a ray of energy. It is not charged and is only very slightly ionising
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What stops alpha radiation?
Paper of a few UMs of air
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What stops beta positive and beta negative radiation?
Aluminium
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What stops gamma radiation?
Lead 2 -3 cm or 1m of concrete.
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What is neutron emission?
When a nucleus is neutron rich it fires a neutron out.
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What causes nuclear decay?
Some isotopes have an unstable arrangment of protons and neutrons. This instability will cause the nucleu sto decay.
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Define contamination
Contamination is when radiation touches an object or surface.
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Define irradiation
Irradiation is when you are exposed to a source but can be stopped.
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What is half life?
The time it takes for half of the total number of radioactivity particles to decay is called half life.
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