The periodic table isn't finished. Not by a long shot.
Most people think it ended with uranium. Think about it: or maybe they remember the synthetic elements from high school chemistry — plutonium, americium, californium — and assume that was the final chapter. It wasn't. The table keeps growing, one painstaking atom at a time, in labs where "discovery" means catching a flash of radiation that lasted less than a blink.
So what was the latest element discovered?
Depends on how you define "discovered.Here's the thing — " And "latest. " And "element.
What Is an Element Discovery Anyway
Here's the thing nobody tells you in textbooks: discovering a new element today doesn't look like Mendeleev predicting gaps in his table. It doesn't look like the Curies processing tons of pitchblende by hand. Modern element discovery looks like this: a particle accelerator slams a beam of calcium-48 ions into a target of berkelium-249 at one-tenth the speed of light. You run the experiment for months. Maybe you get three atoms. Total.
Three atoms. That's your discovery.
Those atoms exist for milliseconds — sometimes microseconds — before decaying into something else. Think about it: you don't hold them. You infer them from the chain of alpha decays they leave behind, like breadcrumbs leading back to a parent nucleus that existed for 0.You don't see them. 0003 seconds. Worth keeping that in mind.
And then you have to do it again. In real terms, reproducibility is the gatekeeper. One lab's claim isn't enough. In practice, the Joint Working Party (JWP) — a collaboration between IUPAC (chemistry) and IUPAP (physics) — reviews every claim. In real terms, they check the decay chains. Even so, they check the cross-sections. In practice, they check whether the data could be explained by something else. Only then does an element get a permanent name and a seat at the table.
The difference between synthesis and discovery
Technically, every element beyond uranium (92) is synthetic. Plus, they don't exist in nature in meaningful quantities — some not at all. The distinction matters historically: neptunium and plutonium were synthesized* first, then later found in trace amounts in uranium ores. No natural occurrence. But "synthesis" and "discovery" get used interchangeably now. Pure synthesis. Elements 95 and beyond? Not even traces.
Why It Matters / Why People Care
You might wonder: who cares about elements that vanish before you can even name them?
Fair question. Plus, you'll never make a battery from tennessine. You'll never build a bridge out of oganesson. Now, these elements exist in quantities measured in atoms*, not grams. Plus, the answer isn't practical applications — at least not directly. Their half-lives are too short, their production rates too low.
But they matter for three reasons:
1. They test the limits of nuclear physics. The island of stability — a theoretical region where superheavy nuclei might live longer — has driven this research for decades. Every new element, every measured half-life, every decay mode observed either supports or challenges the models. We're mapping territory the theory predicted but couldn't confirm.
2. They push technology forward. The detectors, the beam lines, the target fabrication, the chemical separation techniques developed for superheavy element research — those spin off into medical isotope production, nuclear forensics, materials science. The pursuit creates the tools.
3. They complete the picture. The periodic table is one of humanity's great intellectual achievements. It organizes all matter. Finishing the seventh period — which happened in 2016 — was a milestone. Not the end. A milestone.
How It Works: The Modern Discovery Pipeline
Let's walk through how element 117 (tennessine) actually got discovered. It's a good template for the whole modern process.
Step 1: Pick your reaction
You need a projectile and a target that add up to the right proton number. 20 + 97 = 117. Also, for element 117 (117 protons), the Dubna-Livermore collaboration chose calcium-48 (20 protons) + berkelium-249 (97 protons). The neutron numbers also matter — you want the resulting nucleus to land near the predicted island of stability around N=184.
Calcium-48 is special. It's neutron-rich (28 neutrons, magic number), doubly magic, and relatively stable. Worth adding: it's the workhorse projectile for superheavy element synthesis. But it's expensive — separated isotope by isotope in calutrons or centrifuges.
For more on this topic, read our article on what do you think density is or check out 2023 enantioselective synthesis alpha-aminoboronic acid paper.
Berkelium-249? Because of that, half-life: 330 days. The 2009-2010 run used 22 mg. That's a whole other nightmare. You have to make it in a high-flux reactor (Oak Ridge's HFIR), chemically separate it, ship it to Russia (Dubna's JINR), and run the experiment before it decays away. That took months of reactor time and cost millions.
Step 2: Run the beam
The accelerator (Dubna's U400 cyclotron) accelerates calcium-48 ions to ~250 MeV. The beam hits the rotating berkelium target — a thin layer on a titanium foil, spinning to spread the heat. Still, beam current: ~3-5 particle microamperes. That's ~2×10¹³ ions per second.
Cross-section for element 117 production? About 0.5 picobarns.
Let me put that in perspective. On top of that, a barn is 10⁻²⁴ cm². In real terms, a picobarn is 10⁻³⁶ cm². You're trying to hit a target smaller than a proton's cross-section, with a beam that's mostly missing. For every trillion* calcium ions that hit the target, you might get one atom of element 117.
The 2010 run lasted ~150 days. Think about it: they detected 6 atoms. Total.
Step 3: Separate and detect
The recoil separator (Dubna's DGFRS — Dubna Gas-Filled Recoil Separator) sweeps the reaction products away from the target. Magnetic and electric fields separate by mass-to-charge ratio. The heavy recoils (your new element) fly forward; the beam particles and lighter junk get deflected.
At the focal plane: a position-sensitive silicon detector array. On the flip side, it catches the implant. Then it waits.
The implanted atom decays. Even so, alpha particle hits the same pixel. In real terms, energy measured. And time measured. Position measured. Then the daughter decays. And another alpha. Another measurement. Consider this: you build a decay chain: parent → daughter → granddaughter → ... until you hit a known nucleus.
For element 117, the chains looked like:
- ²⁹⁴Ts → ²⁹⁰Mc → ²⁸⁶Nh → ²⁸²Rg → ²⁷⁸Mt → ²⁷⁴Bh → ²⁷⁰Db → spontaneous fission
- ²⁹³Ts → ²⁸⁹Mc → ²⁸⁵Nh → ²⁸¹Rg → ²⁷⁷Mt → ²⁷³Bh → ²⁶⁹Db → spontaneous fission
To confirm the discovery, researchers needed to verify these decay signatures against theoretical predictions and experimental background noise. The key was identifying the unique alpha energy patterns and half-lives that matched expected values for tennessine and its decay products. Statistical analysis showed the observed events exceeded what could be attributed to random background by several standard deviations, meeting the rigorous threshold required for nuclear physics discoveries.
The success hinged on precise timing and coordination across continents. The Oak Ridge team had to produce and ship the precious berkelium-249 target within tight decay constraints, while Dubna's accelerator team maintained beam stability for months. Meanwhile, theorists at Livermore provided critical input on optimal beam energies and expected cross-sections to guide the experimental design.
Beyond the technical achievement, this work opened new frontiers. Tennessine represents humanity's furthest extension into the superheavy element realm, probing nuclear structures where traditional models break down. The experiment validated the existence of the predicted island of stability and demonstrated that elements approaching atomic number 120 might be accessible with future facilities.
That said, the approach faces fundamental limits. Each new element requires increasingly exotic targets and projectiles, with diminishing returns in detection probability. The cost and complexity grow exponentially—making element 118, oganesson, required a target of californium-249, itself produced in particle accelerators.
Future efforts will make use of upgraded facilities like Russia's Super-heavy element accelerator and JINR's enhanced separator capabilities. Alternative approaches explore using lighter projectiles or multi-step fusion processes to reach higher atomic numbers. Yet the fundamental challenge remains: creating and detecting nuclei that exist for microseconds, with cross-sections smaller than astronomical distances scaled to laboratory dimensions.
This collaboration between Oak Ridge, Dubna, and Livermore exemplifies modern big science—where national laboratories spanning continents unite their specialized expertise to push the boundaries of matter itself. Each detected atom represents not just a new element, but a triumph of international cooperation and technological ingenuity in the quest to understand the ultimate limits of nuclear stability.
