Seaborg shared the 1951 Nobel Prize for Chemistry with the physicist Edwin McMillan. In addition to a long career at the University of California and the Lawrence Radiation Laboratory, both in Berkeley, Seaborg was also chancellor of the University of California and head of the Atomic Energy Commission. During the Second World War he was in charge of refining plutonium for the US atomic bomb project. Seaborg suffered a stroke while attending an American Chemical Society meeting last year, and died while convalescing at home. "Dr Seaborg was a true giant of the 20th Century, " said Charles Shank, director of the Lawrence Berkeley National Laboratory.

In 1997 Seaborg became the only person ever to have an element named after them - element 106 - while still alive. This led to a huge row between the American Chemical Society and the International Union of Pure and Applied Chemistry when elements 104 to 109 were being named. Finally, in August 1997, both groups agreed that element 106 should be called seaborgium. Seaborg called this his greatest honour.

Seaborg's main contribution to chemistry was his 1944 paper on the "actinide concept" of heavy element electronic structure. This predicted that the actinides - including the first eleven transuranium elements - would form a transition series analogous to the rare earth series of lanthanide elements. This paper led to one of the most significant changes in the periodic table since Mendeleyev.

Seaborg also served as president of the American Association for the Advancement of Science and the American Chemical Society, and was an advocate of nuclear arms control, international co-operation in science, and conservation of natural resources.