Explain the experiment conducted by Rutherford and how he disproved the plum-pudding model. [3 MARKS]
Experiment : 1 Marks
Disproof : 2 Mark
Rutherford decided to bombard a thin gold foil with alpha particles. An alpha particle is basically a helium atom without any electrons. Hence, its a positively charged species with a mass of 4 amu. He planned on bombarding these alpha particles on the thin gold foil expecting small deflections from throughout the gold foil.
What Rutherford observed was something he didn't expect. He saw that some of the alpha particles passed through the foil without any deflections, whereas other got deflected by small angles. There were also some which got deflected back with large angles. This meant that the entire atom wasn't a positive sphere, rather it had a positive sphere in the middle and most of the atom was actually free space.