Answer:
Addition of a small, dense nucleus to the center of the atom
Explanation:
Most alpha particles were observed to pass straight through the gold foil, which implied that atoms are composed of large amounts of open space. Some alpha particles were deflected slightly, suggesting interactions with other positively charged particles within the atom.
Still other alpha particles were scattered at large angles, while a very few even bounced back toward the source. Only a positively charged and relatively heavy target particle, such as the proposed nucleus, could account for such strong repulsion.
