[lumost]

Sufficiently small non-charged blackholes would have minimal interaction cross sections with any matter. If such a thing was made with an accelerator, it as well as any material it interacted with would likely fly through the planet and out into interstellar space. Even managing to detect that it had been created would be a substantial challenge.

[nine_k]

I suppose for that its Schwartzschield radius should be much smaller than a typical atom?

[lumost]

aye - the Schwarzschild radius of the entire planet is only 8.87 mm. The radius of a 70kg human is 10^12th times smaller than a hydrogen atom. Presuming it is even physically possible for atom massed black holes to exist - hypothetical hydrogen atom black hole would have a radius 10^41 times smaller than a hydrogen atom.

Ultimately the physics of such objects are not well defined, the radius of a hydrogen atom or a proton is defined in terms of electric potentials, calculating the interaction cross section between the quarks in a proton and a hypothetical atom massed black hole is completely ill-defined. At these scales the strong force would dominate - and you'd run into a number of uncomfortable problems which either require hawking radiation to exist or for GR to not conserve energy ( which it doesn't in the classical theory )

but all that being said, whatever collisions created this black hole would surely have left it with a velocity that's a very large fraction of the speed of light.