Atomic mass 260 != element 260. Bismuth-209 has atomic mass ~209 but is element 83 (123 neutrons add the extra mass). An atomic mass of 260 probably means abou

Atomic mass 260 != element 260. Bismuth-209 has atomic mass ~209 but is element 83 (123 neutrons add the extra mass). An atomic mass of 260 probably means about... 100-120 protons? That's a guess from eyeballing this chart: https://en.wikipedia.org/wiki/List_of_elements_by_stability_of_isotopes https://en.wikipedia.org/wiki/List_of_elements_by_stability_... Still very cool, but not (far) outside of what has been synthesized.