Chapter 20.1, Problem 3R

To determine

The reason of the large nuclei to be radioactive is to be explained.

Answer to Problem 3R

The electric repulsion on a proton in a nucleus with large size and thus, with many protons, is large. So, such nuclei are less tightly held together than the nuclei with smaller size and is thus radioactive.

Explanation of Solution

The nucleons inside the nucleus are bound together by the strong forces which operate effectively to only a small distance. They also act likely in the large nuclei but in the large nuclei having so many protons, the electrostatic repulsion on a proton overcome strong forces and thus making the nuclei highly radioactive as in such nuclei the nucleons are less tightly bound.

Conclusion: The large nuclei tend to be highly radioactive because of the larger number of protons leading to enormous amount of electrostatic repulsion.