That's not a terrible place to start. "Under most definitions the radii of isolated neutral atoms range between 30 and 300 pm (trillionths of a meter), or betwe

That's not a terrible place to start. "Under most definitions the radii of isolated neutral atoms range between 30 and 300 pm (trillionths of a meter), or between 0.3 and 3 ångströms." https://en.wikipedia.org/wiki/Atomic_radius https://en.wikipedia.org/wiki/Atomic_radius