The Plum Pudding model was a positive ball with negative electrons evenly embedded.
Rutherford did the alpha scattering experiment which lead to the Nuclear Model.
He shot alpha particles (2p, 2n, 0e) at gold foil. Most particles went straight through, some deflected and very few reflected.
This proved most of the atom was empty space and that the nucleus is very small and contains all protons.
They used an evacuated chamber with fluorescent coating to see where the alpha particles hit the inside of the chamber. They used a microscope to see the path.
α: 2 - 10 cm in air, highly ionising, deflected by fields, absorbed by paper.
β: 1 m in air, weakly ionising, deflected by fields, absorbed by aluminium foil (around 3 mm).
γ: infinite range in air, follows inverse square law, very weakly ionising, not deflected by fields, absorbed by metres of concrete/ inches of lead.
Type of radiation can be determined by a Geiger-Muller tube and counter (to find the background count when there is no radiation).
Then, place the source of radiation close to the tube and measure count rate.
Place a sheet of paper between the source and GM tube and measure count rate again. See if the count rate decreases significantly, then the source is emitting alpha radiation. Repeat for aluminium then lead etc.
You can use the radiation and a detector to check your sheets of paper are the right thickness etc.
Gamma is used in medicine: detector (use short life and gamma cameras), sterilise equipment, radiation therapy (low exposure times, shielding).
I = k/x2. I: intensity of radiation, k: constant, x: distance from source.
Radioactive sources must be handled safely: long handled tongs to move the source, store the source in a lead-lined container when not in use, keep source as far away as possible, never point the source towards others.
Corrected count = total count rate − background count because background radiation is around us constantly.