Chapter U1.11, Problem 2E

Interpretation Introduction

Interpretation:

The evidence that caused Rutherford to change Thomson’s plum pudding model to nuclear model must be explained.

Concept introduction:

Rutherford’s gold foil experiment was an experiment to know about atom and nucleus.

A very thin gold foil was chosen which was bombarded with fast moving alpha particle which has positive charge $He$.

Answer to Problem 2E

Most of the alpha particle in the gold foil experiment passed through the foil without a significant deflection. This caused Rutherford to change the Thomson’s plum pudding model to nuclear model.

Explanation of Solution

From the experiment it was understood that the arrangement of nucleus and electrons is not homogeneous like plum pudding model of Thomson.

Most of the space of atom is vacant as maximum alpha particle didn’t suffer much deflection.

Very few alpha particles(1 per 20000 cases) returned back after coliding with the nucleus. This has proved that maximum mass of the atom is centered at the nucleus which is very small zone as compared to the whole atom.

Conclusion

No deflection of maximum alpha particles caused Rutherford to change the plum pudding model of Thomson.