Which element has the highest atomic number?
Oganesson
In late 1998, Polish physicist Robert Smolańczuk published calculations on the fusion of atomic nuclei towards the synthesis of superheavy atoms, including oganesson.[23] His calculations suggested that it might be possible to make oganesson by fusing lead with krypton under carefully controlled conditions, and that the fusion probability (cross-section) of that reaction would be close to the lead–chromium reaction that had produced element 106, seaborgium. This contradicted predictions that the cross-sections for reactions with lead or bismuth targets would go down exponentially as the atomic number of the resulting elements increased.[23]