Why nuclear radiations occur in atoms with large nucleus?

[abi.ayan]

why nuclear radiations occur in atoms with large nucleus?Is it the weakening of residual strong force?
If so why it gets weak ?

 

[SteamKing]

Radiation also occurs in atoms with a small nucleus, for example tritium (H-3) and carbon-14.

 

[mfb]

why nuclear radiations occur in atoms with large nucleus?Is it the weakening of residual strong force?
If so why it gets weak ?

It does not get weak, but the repulsion between all those protons grows quicker than the binding due to the residual strong force*. Therefore, as a general tendency, very big nuclei are more likely to decay in some way.

*the binding energy due to the strong force is (approximately) proportional to the number of nucleons. On the other hand, every proton is repelling every other proton in the nucleus - this contribution grows with the squared proton number.

Small nuclei with a very unbalanced proton/neutron ratio are unstable, too.

 

[abi.ayan]

It does not get weak, but the repulsion between all those protons grows quicker than the binding due to the residual strong force*.

But in tritium atom there is only one proton.Hence there will be no repulsion.So why do it radiate??

 

[snorkack]

But in tritium atom there is only one proton.Hence there will be no repulsion.So why do it radiate??

Imbalance between protons and neutrons. A lone neutron radiates as well.

In fact, tritium atom radiates much less energy than a lone neutron does. A deuteron repels a proton, and that decreases the radiation energy of the extra neutron. Just not enough to stop the radiation altogether, like with lithium 7.

 

[mfb]

But in tritium atom there is only one proton.Hence there will be no repulsion.So why do it radiate??

The part you quoted was about alpha radiation - something you mainly find at big nuclei.

Helium-3+electron+neutrino is lighter than tritium (the mass difference between protons and neutrons is relevant here), therefore tritium can decay.