History of the atom

• 1800s Dalton described atoms as solid spheres
• 1897 Thompson discovered the electron - plum pudding model

  
• 1909 Rutherford fired positively charged alpha particles at a thin sheet of gold. they expected them to go straight through but most passed through and many deflected to the side some even deflecting backwards - this proved the plum pudding model wrong.
• rutherford created the nuclear model - a compact nucleus with a cloud of electrons.
• why was rutherfords nuclear atom theory flawed

  the cloud of electrons meant that nothing was stoping the electrons from rushing into the nucleus and collapsing on itself
• 1913 - Bohr - electrons orbit the nucleus and are held in shells
• after Bohr, Rutherford discovered that the nucleus can be divided into smaller particle called protons
• after the discovery of the protons, Chadwick discovered the neutron
• order of discovery in the atom: electron (1897 - Thompson), proton (1917 - Rutherford), neutron (1932 - Chadwick)