Did you know that the scientists that detonated the first nukes were honestly not sure at the time if the chain reaction of the nuclear material would continue on into the atmosphere and ignite the entire earth. They went ahead anyways, and fortunately learned that it does not.. but makes you wonder. heh

It's possible the collider at CERN already has. They would be very small and dissipate almost immediately.

Where would they get enough mass for it to be even noticeable?

that’s something to hope for

No, because they'll create a white hole as well.

No because I’m the black hole