In the experiment Rutherford directed a positively charged alpha particle at a ultra-thin sheet of gold fold. Surprisingly, almost all the particles passed directly through the foil, while others got deflected, or even bounce backwards. This experiment led Rutherford to conclude that the mass and the positive charge of an atom must all be conentrated in a space that is smaller than the atom itself. Unlike the plum-pudding model, which suggested the atom was a huge sphere with tiny electrons on its surface. According to Rutherford, the atom must contain large regions of empty space dotted with small regions of dense matter.