Chapter U1.11, Problem 1E

Interpretation Introduction

Interpretation:

The evidence needs to be explained that made Thomson to change the Dalton’s mode of solid sphere into plum pudding model.

Concept introduction:

To explain structure of atoms different models were proposed. Solid sphere model considers that atom can’t be divided.

Answer to Problem 1E

Thomson found that cathode ray elements have negligible mass as compared to atom. These are sub-atomic particles known as electron. So he proposed plum pudding model.

Explanation of Solution

As per Dalton’s atomic model each atom is a solid sphere which can’t be divided further. Thus atom is the smallest fundamental particle. However after the discovery of electron it is found to be wrong and atom can be divided. So to put electron along with nucleus Thomson proposed plum pudding model.

Conclusion

Discovery of electron as a sub-atomic particle caused Thomson to change Thomson’s solid sphere model into plum pudding model.