Adapted from an image by 文部科学省 (CC BY 4.0), via Wikimedia Commons.
Kosuke Morita
Discovered nihonium in 2004.
On the timeline
The seventh row is complete
IUPAC confirmed the discoveries of elements 113, 115, 117 and 118, by teams in Japan, Russia and the United States, filling the seventh row of the periodic table.
Four new names
IUPAC approved nihonium, moscovium, tennessine and oganesson, after Japan, Moscow, Tennessee and the physicist Yuri Oganessian.
IUPAC announces the names of the elements 113, 115, 117 and 118IUPAC
Element
A team at RIKEN in Japan, led by Kosuke Morita, spent years firing zinc at bismuth and made three atoms of element 113, the last in 2012. In 2015 it became the first element discovered in Asia, and it was named nihonium, after Nihon, Japan.
Morita's team spent nine years making three atoms of element 113. See where it sits on the way to the island of stability.
The island of stability
Every element heavier than lead is radioactive, and the heavier they get, the faster they fall apart. Nihonium’s longest-lived known form, Nihonium-286, has a half-life of 9.5 seconds. Yet physicists predict that a little further on there is an “island” of heavier nuclei that should last much longer.
Nihonium-286 half-life 9.5 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.
- Under 1 ms
- 1 ms – 1 s
- 1 s – 1 min
- 1 min – 1 h
- 1 h – 1 day
- Over a day
- Very uncertain
Nihonium-286
113 protons and 173 neutrons. Half-life 9.5 seconds; it gives off an alpha particle. That’s 11 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.
Keep exploring
Where the dates and stories on this page come from; each event on the timeline links to its own source. RIKEN gives the year only.
- Element 113 has an official nameRIKEN
- Element 113RIKEN
- Kosuke MoritaWikipedia