Changing Atomic Model

• Ancient greek model of the atom

  Atoms are tiny solid spheres which cannot be divided.

  
• JJ Thompson


  Discovered the electron and developed the "plum-pudding" model of the atom

  
• plum pudding model of the atom


  atoms are balls of positively charge with negative electrons embedded in it

  
• Rutherford, Geiger, and Marsden


  carried out the alpha particle scattering experiment and developed the nuclear model of the atom

  
• Alpha particle scattering experiment

  Fired alpha particles at a thin sheet of gold foil.

  
• Conclusions of the alpha particle scattering experiment

  Most of the atom is empty space except for a tiny positive nucleus.

  
• Observations of the alpha particle scattering experiment

  Most of the alpha particles went straight through the atom, a few alpha particles bounced back.

  
• Nuclear model of the Atom

  Atoms are made of a small positive nucleus orbited by negative electrons.

  
• Niels Bohr


  Adapted the nuclear model, by suggesting that electrons orbit the nucleus at specific distances.

  
• James Chadwick


  Carried out experiments which provided evidence of neutrons.

  
• Proton


  A subatomic particle that has a positive charge and that is found in the nucleus of an atom.

  
• Neutron


  A subatomic particle that has no charge and is found in the nucleus of an atom.

  
• Electron


  A subatomic particle that has a negative charge and orbits the nucleus in shells.