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AQA A-Level Physics Topic 8 - Nuclear Physics
This is a draft cheat sheet. It is a work in progress and is not finished yet.
Rutherford scattering
This experiment demonstrated the existence of a small, dense and positively-charged nucleus |
Alpha particles were fired at thin gold foil, and a detector recorded how many particles are deflected at different angles |
Alpha particles are the nucleus of a helium atom and are positively charged |
Most of the particles went straight through = atom is mainly empty space |
Some particles were deflected at different angles = positive nucleus at the centre |
A small number were deflected straight back = the nucleus is small and is where the mass/charge of an atom is concentrated |
History of the atom model
Atomism - Democritus (All matter made of small indivisible particles called atoms) |
Sphere model - Dalton (Atoms of the same element are identical, cannot be broken down and rearrange during reactions) |
Plum Pudding Model - J.J. Thomson (Atom is a positive sphere with negative charges embedded in it) |
Nuclear Model - Rutherford (Electrons orbit a positive nucleus in set, predictable paths) |
Planetary Model - Bohr (Electrons are arranged in specific orbits around the nucleus) |
Quantum Model - Schrödinger (An atom is surrounded by an cloud containing all the possible places an electron could be) |
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α, β and γ radiation
Radiation is where an unstable nucleus emits energy in the form of EM waves, or subatomic particles |
It does this in order to become more stable |
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