Development of Atom

• Dalton Model

  Solid Spheres
• JJ Thompson

  Plum Pudding-Ball of positive charge with electrons embedded in/throughout it
• Rutherford

  Alpha Scattering Model-Fired positive alpha particles through very thin gold foil

  Observations:

  Most went through so most atom is empty space,Some were deflected so mass is concentrated in a positive nucleus(like charges repel)
• Neil’s Bohr

  Electrons orbit in shells
• Protons

  Discovered in 1920
• James Chadwick

  Discovered neutrons in 1932 and this was important for isotopes