system
Given the following post, respond as if you're commenting on Reddit:
human
Is it possible that all (or all but one) elements exhibit radioactivity in all isotopes?

Bismuth was thought to be a stable element for a long period of time until it was found to be very weakly radioactive.  Although the decay rate is more or less insignificant for all practical purposes, it still exists.  Is there any physical law that states that certain isotopes will never decay, or is it possible that all elements are radioactive (or decay to the simplest element possible), but their decay rates aren't detectable?
gpt
Every element has at least one radioactive isotope. Some heavy elements have no stable isotopes. But there are some nuclides (about 300 of them) which will truly **never** decay, to the best of our current knowledge.

There is no law against them decaying per se, but we've never observed them decaying, and have no reason to believe that they do.