Element 43, Technetium, is only very rarely found in nature because it has no stable isotope.
I don’t get it.
Why is this particular element not stable when all the ones around it are? The higher number elements get unstable, but that I understand, sort of. Why is poor little Tc doomed to instability when all; the elements around it have nice, stable isotopes and can hang around awhile?
Here is the answer to your question. WebElements Periodic Table » Technetium » the essentials
I may be slow today, but I can’t find where that link addresses the OP’s question.
Perhaps this is the answer? I am no chemist.
Well, it’s no accident that an element with no stable isotopes (Technetium) has an odd number of protons (43). Even numbers of nucleons are, as a general rule, far more stable than odd ones. Take a look at the table of nuclides; Zirconium (40) has four stable isotopes, molybdenum (42) has six, and ruthenium (44) has seven. Compare to some nearby odd-numbered elements: Rubidium (37), yttrium (39), niobium (41), and rhodium (45) all have only one stable isotope. The concept of a magic number may also help in understanding this.
That doesn’t help: Both statements are also true of lead, and there are plenty of stable isotopes of lead. In fact, if you just start with a sample of radioactive material, and just let it keep on decaying, you have to get to a stable byproduct eventually.
The short answer to the OP’s question is that there are a lot of factors that go into determining stability, and Tc just happened to draw the short straw on all of them. But nuclear physics isn’t really my specialty, so I’ll let someone else explain what those various factors are.
Yeah, that’s the impression that I got when looking up the research, though the details were hard to comprehend well enough to digest them for someone else on a message board - sort of a ‘perfect storm of instability’.
Of course misery loves company, so Technetium can take heart that Promethium is anomalously unstable too.