Q1.
You may wonder that since all the protons with like charges are squished together in a nucleus why do they not push each other away?
Answer
They do repel one another — but a much stronger attraction, the nuclear force, holds the nucleus together, and the neutrons are what make that possible.
Neutrons help in two ways:
- Being uncharged, they sit between the protons and increase the distance between them, which weakens the electrostatic repulsion.
- They add to the nuclear force — the short-range attraction that acts between all nucleons (proton–proton, proton–neutron and neutron–neutron alike) and binds them tightly.
This is why the neutron-to-proton ratio rises as atoms get heavier. Count them:
| Element | Protons | Neutrons | n : p |
|---|---|---|---|
| Carbon | 6 | 6 | 1.00 |
| Oxygen | 8 | 8 | 1.00 |
| Iron | 26 | 30 | 1.15 |
| Uranium | 92 | 146 | 1.59 |
Why it happens: the two forces behave differently with distance. Electrostatic repulsion is long-range — every proton pushes on every other proton right across the nucleus. The nuclear force is short-range — it acts only between nucleons that are practically touching. So as a nucleus grows, the total repulsion grows faster than the binding attraction, and extra neutrons are needed to keep it stable. Beyond a point no ratio works, which is why the heaviest nuclei are radioactive.