Seaborg's americium dispute put to bed 60 years later

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.