Z     N     s
 odd  odd 0.015
 odd even 0.18
even  odd 0.205
even even 0.6

Z  > 82 -> unstable
Z <= 20 -> stable n/p is nearly 1 (0.775 - 1.29)
Z  > 20  & Z <= 82 -> stable n/p between 1:1 and 1.5:1
Z  > 92 -> spontaneous fission
Z  > 52 -> alpha rays possible

Can induce fission by neutron bombardment.
Too many neutrons -> beta decay, neutron emission
Too few neutrons -> electron capture, positron emission, proton emission

Alpha: Emits 2Z-2N
Beta: Emits e, 1N -> 1Z
Electron capture & Positron emission: Emits e+, 1Z -> 1N