Are you referring to Rutherford's famous experiment, the one where he fired alpha particles at a thin sheet of gold, expecting them to go through the sheet which a majority of did but some reflected off or were deflected at odd angles? if so then...
The alpha particles that were almost completely reflected hit the nuclei of an atom. An atom's nuclei is massive (full of mass) but compared to at entire atoms radius they are tiny which is why so few were reflected. This is why Rutherford was quoted 'It's like firing a shell at a sheet of paper, and the shell bouncing back' It was that suprising to him because before that he had accepted the traditional 'Plum Puddiing' assumption of atomic structure.
The alpha particles that were deflected off and less obtuse angles where, so did not follow the beam, were repelled by the charge of the nucleus of the gold atoms. The electrons had very little-no deciding factor in the path of the alpha particles.
Im not sure if this has helped answer your question or if you wanted a more detailed answer but oh well, this is the best i can give!