Mod-01 Lec-24 Radioactivity, Alpha Decay

We close this chapter on nuclear models, we had discussed enough of shell model, liquid drop model, collective models that we have discussed. Now, the next chapter or section that I am going to take is on radioactive decays. So, as such you know radioactive decay from your schooldays, if you have certain unstable nuclei, which decay by either alpha

particle emission or beta particle emission, we had talked about these emissions these decays in this course also little bit. So, the stability of nucleus, you know it depends on the N Z combination, you can look at your screen and that N versus Z stability that we had discussed. So, on the horizontal side you have proton number, on the vertical side you have this neutron number and the

black dots or black rectangles, that you see on the screen, they represent stable nuclei. So, you have a specific N Z combinations, which result in the stable nuclei, otherwise if you have more neutrons or more protons than that required, you get that beta decay proton converting to neutron or neutron converting to proton

Now, you look at this diagram and you see that, somewhere above the certain value, you do not have any nuclei up to here, you have all these black dots and beyond this, you do not have any black dots. And this corresponds to roughly, this is something like 80, 85’s like that, Z is 85 something of that sort and this side, if I go here, this will be

somewhere 130, 125 so N is 125. So roughly, this region A is equal to 200 or 210 after that heavier than that, you do not have any stable nucleus so that is one thing with which, you can note from here. Here, you have specific N Z combinations, giving you stable nuclei, here you have specific N Z combinations and so on. But here, no N