atoms of an element are identical to one another but different from atoms of other elements.

atoms of one element cannot be converted into atoms of another element. AND if they already knew that the electron was small and negative, then the atom must have a small positive nucleus with the electrons around them. Daltons 'modern' atomic theory, in todays terms, would be something like this: all matter consists of indivisible atoms which cannot be created or destroyed. If the positive alpha particles mostly passed through the foil, but some bounced back. Heisenberg also worked on the theory of the atomic nucleus following the discovery of the neutron in 1932, developing a model of proton and neutron interaction in an early description of what decades later came to be known as the strong force.

How could that be if the plumb pudding model was correct? Rutherford's experiment prompted a change in the atomic model. Rutherford found that most of them went right through the foil. The atomic, microscopic way of looking at matter is actually a fairly new development. If you shoot these positive alpha particles at this positive pudding atom, they should mostly bounce off, right? Well, that is not what happened. He shot some alpha particles (which are really just the nucleus of a helium atom) at some really thin gold foil. In StoryboardThats fun activity, students will create a timeline that details key events in the history of the atom, highlighting key discoveries. Ernest Rutherford said one day 'hey, I think I will shoot some stuff at atoms.' I am sure his wife said 'oh, Ernie' (she probably called him Ernie) 'if it makes you happy to play with your little physics stuff, go ahead.

History of atomic theory