Atoms Structure -

Nucleus [protons[positively] and neutrons[no charge]] surrounded by electrons [negatively]

Rutherford Experiment - Supports nuclear model of atom by the scattering of alpha particles by a sheet of thin metal

  1. Beam of alpha particles [Helium ions] were directed at thin gold foil
  2. Alpha particles = Expected to travel through and maybe change direction a bit
  3. Instead - CANNOT BE EXPLAINED BY PLUM PUDDING MODEL
    1. Most passed straight through - due to atom being mainly empty space
    2. Some changed direction - positive alpha particles get repelled by positive nucleus
    3. Few bounced back - due to nucleus being very small

THEREFORE - new model needed to be created

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Atoms and Ions -

  1. Ion = electrically charged atom due to loss or gain of electron
  2. Stable atom = protons = electrons
  3. Positive ion = lost electron
  4. Negative ion = gained electron

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proton number = atomic number = number of protons

nucleon number = number of protons + number of electrons