[gomess]

Why did Rutherford think that most of the alpha particles would pass through the gold foil? Wasn't J J Thompson's model electrons in a positively charged 'bun' ? Wouldn't this also induce electrostatic repulsion? Also, how did Rutherford conclude that the electrons orbited the positively charged and weren't stationary? Any insight would be really appreciated!

[Arkcon]

According to this account here: http://en.wikipedia.org/wiki/Geiger%E2%80%93Marsden_experiment  He expected the thin gold foil to deflect the beam of alpha particles slightly, and the distribution of slight deflections was supposed to give insight into the distribution of electrons in the plum pudding model.  What's surprising was that, not only was there often no deflections at all, but that there was some rare 180 degree deflections.