Why would elements become stable again around atomic number 115?

[Forestman]

When I was in high school someone told me once that for some strange reason that I do not understand that elements would start becoming stable again after reaching the atomic number 115. I don't see how this would be possible though because it seems like the positive force of so many protons would blow it apart.

 

[mgb_phys]

But you also have a bunch more neutrons - it's all to do with shells and energy levels being filled.
It's called the island of stability http://en.wikipedia.org/wiki/Island_of_stability

 

[Forestman]

Thanks mgb_phys, I have always wondered about that.

 

[mathman]

The stability is relative not absolute. Specifically, in the island of stability the half-lives are expected to be longer than for nuclides with a few less protons.

 

[seerongo]

If 115 offers a magic number isotope, is there any guess as to what that half-life would be? I see that 288 was synthesized and seems have a h/l of ~ 85 ms. I also read that there was speculation that 299 would be the most stable isotope, but I also read that 345 (wow) should be the most stable, considering "hindrance of fission by odd particles." I haven't seen any speculation on just how stable 345 might be, though, and I was wondering if there have been any such guesses made.