10. Explain why the observation of alpha particles scattered at very large angles led Rutherford to reject Thomson’s model of the atom and to propose a nuclear model.

Thomson's plum pudding model viewed the atom as a massive blob of positive charge filled with dotted negative charges. So, if this theory was true then almost all the particles should've gone straight. But as he saw large deviations in the he discarded the Thomson's model of the atom and proposed his own nuclear model. So, he proposed that the atom is mostly empty space. The electrons revolve in circular orbits about a massive positive charge at the center. His model explained why most of the$\alpha$-particles passed straight through the foil. The small positive nucleus deflected the few particles that came close and the few who hit the nucleus were deflected with large deflections.

Thus, The nuclear model replaced the plum pudding model. The atom now consisted of a positive nucleus with negative electrons in circular orbits around it .