In many places, the answer is uranium. The isotope uranium-238 is typically considered to be the heaviest element found in the natural world. It’s atomic mass is 238 – 92 protons and 146 neutrons.

An international research team has successfully conducted ultra-precise X-ray spectroscopic measurements of helium-like uranium ... strong Coulomb fields of the heaviest nuclei for the first ...

Like uranium 235, element 94 would be an incredibly powerful ... and tends to separate into its lighter and heavier components as it cycles around the column. But by 1941 they gave up on this ...

The target consists of a thin layer of an element heavier than uranium. The product formed during the fusion reaction can be ...

At the other end of the spectrum, the heaviest natural chemical element, uranium, is a very dense, radioactive metallic solid. It has 92 protons and, thus, is much lighter than the four just added to ...