Superheavy element

A chemical element with atomic number greater than 103. Its known isotopes are highly radioactive and generally short-lived.

Nuclear shell model: A model describing protons and neutrons as occupying quantized energy levels within an atomic nucleus. Shell structure may confer extra stability on some superheavy nuclei.
Heavy-ion fusion: A reaction in which accelerated atomic nuclei collide and may fuse into a heavier nucleus. Experiments use these collisions to create many superheavy elements.
Rutherfordium: Chemical element 104, a synthetic radioactive metal in the transactinide series. Its discovery involved competing claims that exposed the difficulty of identifying new elements.
Transfermium Wars: A series of disputes over priority for discovering elements with atomic numbers 104 through 106. These disputes prompted a formal reassessment of several superheavy-element discovery claims.
Neutron-rich superheavy nuclei: Superheavy nuclei containing more neutrons than isotopes currently produced in laboratories. They may lie closer to predicted stability and clarify the island's location.
Island of stability: A predicted region of relatively longer-lived superheavy nuclei associated with closed nuclear shells. It explains why some undiscovered superheavy isotopes might outlast known ones.
Cold fusion (nuclear physics): A heavy-ion fusion approach using lead or bismuth targets and relatively low excitation energy. This reaction strategy produced several superheavy elements with comparatively neutron-rich nuclei.
Seaborgium: Chemical element 106, a synthetic radioactive metal named after chemist Glenn T. Seaborg. Its discovery illustrates how independent experiments can confirm a superheavy element.
Joint Institute for Nuclear Research: An international research center in Dubna, Russia, with major programs in nuclear physics. Its accelerator experiments have produced many of the heaviest known elements.
Nuclear stability: The tendency of an atomic nucleus to resist radioactive decay or breakup. Limits on stability determine whether still heavier elements can exist long enough to detect.

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