# Isotope stability

1. Feb 28, 2008

### nordica

hello,
new & amazed by all the knowledge and passion on these forums..wow! well no questions are stupid i hope. I've been looking into basic radioactivity lately and it has led me to some question marks about isotopes' stability. The isotopes in question are $$^{108}$$Ag and $$^{110}$$Ag with the half lifes of respectively ca 142 and 25 seconds. Fine, i thought in my simple mind, the 110 has more excessive neutrons that makes it more unstable. Then of course realized the crack in that, since for example $$^{109}$$Ag is in fact stable. And so on. So obviously it's not that simple, but can someone explain what factors determine a nucleus's stability? I mean i know it has to do with proton-neutron ratio and binding energy but when looking at something like this example, i have a hard time seeing how it makes sense. (I hope I make sense though, english being my 2nd language and scientific english about my 23rd..)

2. Feb 28, 2008

### mathman

I am no expert in this field, but it looks like around 108 nucleons, Ag is stable. The stable isotopes being 107 and 109. It might be that in this case an even number of neutrons is more stable than an odd number, thus 108 is radioactive.

3. Feb 28, 2008

Staff Emeritus
There are very few stable nuclei with both an odd number of neutrons and protons: Deuterium, Li-6, B-10, N-14. K-40 and V-50 are almost stable.

4. Feb 29, 2008

### nordica

Oh! I see. Wasn't familiar with the significance of odd/even, i will read up a bit on that. thanks a lot!

5. Feb 29, 2008