Hotly debated historical brouhaha that centred on the element’s covalency may have been solved
After pioneering American radiochemist Glenn Seaborg voiced his suspicions that the elements after and including uranium constitute a distinct post-actinium series that he called the actinides, he had another hunch. In 1954 he suggested that americium – the next-heaviest element after plutonium and discovered by Seaborg’s team at the University of California at Berkeley in 1944 – uses its 5f orbitals to form partly covalent bonds with chlorine.