Atomic structure

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Atomic structure
- plum pudding model
  - spheres of positive charge
  - filled with negative electrons
- Rutherford
  - fired alpha particles at thin gold foil
  - they werre deflected more than expected
  - thought that there must be a nucleus
    - first nuclear model
- current atom model
  - nucleus contains protons and neutrons
    - overall positive charge
  - surrounded by shells contaiing electrons
    - 2, 8, 8
  - radius ia abbout 1*10^-10 m
- isotopes
  - different forms of the same element
  - same amout of protons but different amout of neutrons
  - ionising radiation
    - alpha, beta, gamma
- alpha
  - helium nuclei
  - strongly ionising
- beta
  - highspeed electrons
  - no mass and a charge of -1
  - moderately ionising but absorbed by 5mm of aluminium
  - one neutron turns into an electron
- Gamma rays
  - EM waves with a short wavelength
  - penetrate far without being stopped
  - weakly ionising and absorbed by thick sheets of lead
- Half life
  - timetaken for radioactive nuclei to halve
    - measure with a graph
- Irradiation
  - exposure to radioactive nuclei
  - outside the body, Beta and Gamma are most dangerous
    - inside the body, Alpha is the most dangerous
outside the body, Beta and Gamma are most dangerous
- inside the body, Alpha is the most dangerous