Describe the history of the atom.

1)19th century - John Dalton - solid spheres 2)1897 - JJ Thomson - plum pudding - Experiments of charge and mass showed a positively charged ball with electrons embedded - plum pudding 3)1909 - Ernest Rutherford - Alpha particle - Positive alpha particles fired at thin sheet of gold - expected to pass through or slight deflection - most went through but some were deflected more than expected, some backwards - came up with nuclear model - concentrated positive nucleus with cloud of electrons, mostly empty space 4)Scientists realised a cloud of electrons would collapse - Niels Bohr nuclear model meant electrons were in shells at a fixed orbit 5)Rutherford and others conducted nucleus had smaller particles which had same charge as a hydrogen nucleus - protons 6)James Chadwick conducted experiments showing evidence for neutrons .