The four newest entries on the periodic table — nihonium, moscovium, tennessine and oganesson — have never been seen by anyone. Not in the ordinary sense. Each was inferred from a chain of radioactive decays recorded by silicon detectors, the fingerprint of a nucleus that existed for somewhere between a millisecond and a second before falling apart. Oganesson, element 118 and the current end of the table, has a half-life of roughly 0.7 milliseconds. Fewer than half a dozen atoms of it have ever been made. That is what a modern element discovery looks like: not a substance in a flask, but a handful of electronic signatures and a very long argument about what they mean.
The manufacturing method has barely changed in principle since the 1950s. Take a target of some heavy actinide — berkelium, californium, curium — often supplied by the Oak Ridge National Laboratory in Tennessee, one of the only places on Earth that can breed such material in reactor quantities. Bombard it for months with a beam of lighter ions, the workhorse being calcium-48, a rare isotope whose unusual neutron surplus gives the fused nucleus a fighting chance of holding together. The beam delivers trillions of ions per second; almost all of them miss, bounce off or shatter the target nucleus. The cross-section for a successful fusion — the effective bullseye — is measured in picobarns, a unit so small that a campaign at the Joint Institute for Nuclear Research in Dubna, Russia, or the GSI laboratory in Darmstadt, Germany, counts a season with three confirmed atoms as a triumph. Japan's RIKEN institute needed nine years of beam time to produce the three atoms of element 113 that earned it nihonium, the first element credited to an Asian laboratory.
Proving you made one is harder than making it. The new nucleus recoils out of the target into a separator, which filters the debris magnetically, and is implanted in a detector that then watches for its decay. What arrives is anonymous; identity comes from the chain of alpha particles it emits as it sheds protons and neutrons, each decay a rung down a ladder that must eventually connect to an isotope already known. If the ladder ends somewhere unmapped — as happened with early claims for elements 115 and 117 — the evidence is suggestive rather than conclusive, and the referees say so.
The committee that owns the table
Those referees sit on a joint working group of IUPAC, the International Union of Pure and Applied Chemistry, and its physics counterpart IUPAP. The group applies criteria first codified in 1991: reproducibility, a credible decay chain, and independent confirmation where possible. Only when it formally assigns priority may the credited laboratory propose a name, and even then the choices are fenced in. A 2016 IUPAC rule confines names to five sources — a mythological concept, a mineral, a place, an elemental property, or a scientist — with endings fixed by column: -ium for most, -ine for the halogen group, -on for the noble gases, which is why element 117 is tennessine and 118 oganesson. The proposal then sits in public consultation for five months, a genuine veto window; the provisional systematic names, placeholders such as ununennium for the as-yet-unmade element 119, hold the fort meanwhile.
The fences exist because naming once turned poisonous. Through the 1970s and 1980s, American and Soviet laboratories filed rival claims to elements 104, 105 and 106, and taught rival names to a generation of students — the episode chemists still call the transfermium wars. The 1997 settlement split the honours, giving Dubna element 105 as dubnium, and nearly foundered on element 106: the Americans wanted seaborgium, after Glenn Seaborg, and IUPAC initially objected that elements were not named after living people. Seaborg won; the precedent later allowed oganesson to honour Yuri Oganessian while he was alive to enjoy it, only the second person so recognised.
National pride never left the process, it was merely domesticated. Nihonium put Japan on the table; moscovium and tennessine planted flags for Moscow and Tennessee. Britain's contributions belong to an earlier era — William Ramsay's London laboratory bagged four noble gases in the 1890s — and no UK facility now competes in the superheavy hunt. The next contest is already running: Dubna and RIKEN are both chasing element 119, which would open an eighth row of the periodic table, using titanium-50 beams because the calcium-48 trick runs out of stable targets. Whoever gets a confirmed decay chain first wins a naming right that, on current form, will take the committees several careful years to hand over.
