1913–1990

Georgy Flyorov

Founded the laboratory at Dubna, near Moscow, where many of the heaviest elements were made.

Elements

Flerov's laboratory has spent decades sailing towards the island of stability. Explore it.

Superheavy elements

The island of stability

Every element heavier than lead is radioactive, and the heavier they get, the faster they fall apart. Flerovium’s longest-lived known form, Flerovium-289, has a half-life of 2.4 seconds. Yet physicists predict that a little further on there is an “island” of heavier nuclei that should last much longer.

The longest-lived form of each elementFor each element from lead onwards, the half-life of its longest-lasting known isotope: how long it takes for half of a sample to decay. The scale is logarithmic, so each step up is ten times longer. Hover or tap a point to see it.
Age of the universeA million yearsA yearA dayA secondA millisecondPbUFmDsOg

Flerovium-289 half-life 2.4 seconds

From uranium, which has lasted since before the Earth formed, lifetimes plunge. But from rutherfordium (104) on, the fall flattens out to seconds and minutes. Those longest-lived forms are also the most neutron-rich ones made so far: more neutrons help, just as the island idea predicts.

Walk towards the islandEach square is one nuclide: a particular number of protons (which element it is) and neutrons. Darker squares last longer. Squares with a dashed outline were measured from only a few atoms, so their half-lives are very uncertain. Tap a square, or use the buttons, to see it.

120119OgTsLvMcFlNhCnRgDsMtHsBhSgDbRfLrNo150160170180184Predicted island
  • Under 1 ms
  • 1 ms – 1 s
  • 1 s – 1 min
  • 1 min – 1 h
  • 1 h – 1 day
  • Over a day
  • Very uncertain

Flerovium-289

114 protons and 175 neutrons. Half-life 2.4 seconds; it gives off an alpha particle. That’s 9 neutrons short of the island’s predicted centre at 184.

Along each row, adding neutrons mostly makes the nucleus last longer. But no one has made a superheavy nucleus with more than 177 neutrons: they are made by fusing two lighter nuclei, and lighter nuclei don’t have enough neutrons to spare.

Why an island?

  • Magic numbers

    Protons and neutrons fill shells in the nucleus, much as electrons fill shells around it. Full shells are extra stable: lead-208, with 82 protons and 126 neutrons, is doubly “magic” and never decays.

  • The next full shells

    Theory predicts the next magic numbers at about 114 protons and 184 neutrons. Estimates of how long nuclei there would last range from minutes to far longer; no one knows.

  • Made an atom at a time

    Superheavy elements are made by firing a beam of one element at a target of another for weeks. Only a handful of atoms of the heaviest, like oganesson, have ever been seen.

Half-lives and decay modes from the IAEA Live Chart of Nuclides (ENSDF). An element’s longest-lived form counts only half-lives measured to better than their own size; values from only a few atoms are shown on the map with a dashed outline. The island’s outline is a sketch of where theory puts it, not a measurement.

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