Superheavy elements are elements with 104 or more protons in their atomic nucleus. They don’t exist naturally on Earth. Every single one has been created artificially inside particle accelerators by smashing lighter atoms together at enormous speeds. As of 2024, the heaviest element ever made is oganesson, element 118, which was officially named in 2016.
What Makes an Element “Superheavy”
Every element on the periodic table is defined by how many protons sit in its nucleus. Hydrogen has one, carbon has six, gold has 79. Superheavy elements start at 104 protons and go up from there. They’re also called transactinide elements because they come after the actinide series on the periodic table, which ends at element 103 (lawrencium).
What sets superheavy elements apart isn’t just their size. Past about 82 protons (lead), atomic nuclei become increasingly unstable. The more protons you pack together, the harder it is for the nuclear forces holding the atom together to overcome the electrical repulsion of all those positively charged particles trying to push apart. Superheavy atoms are so packed with protons that most of them fall apart almost instantly after being created, often in fractions of a second or less.
How Scientists Create Them
The basic recipe is deceptively simple: smash two lighter atoms together so their combined proton count equals the element you want. In practice, this is extraordinarily difficult. You need a particle accelerator to fire a beam of one element into a target made of another element at precisely the right energy. Too little and the nuclei bounce off each other. Too much and the resulting atom shatters immediately.
For years, elements 114 through 118 were all made using a beam of calcium-48, a rare isotope with a special balance of protons and neutrons that makes it unusually good at fusing with heavier target atoms. In 2024, researchers at Berkeley Lab demonstrated a new approach, fusing titanium with plutonium to create element 116. This matters because titanium beams open the door to creating even heavier elements. To attempt element 120, for example, scientists plan to fuse titanium with californium.
Even when everything goes right, success is vanishingly rare. A beam might deliver trillions of atoms per second into a target, and researchers may wait weeks or months before a single fusion event produces the atom they’re looking for. Sometimes it never happens at all.
Why They Vanish So Quickly
Most superheavy elements exist for tiny fractions of a second before decaying into lighter elements through radioactive processes. The nucleus simply can’t hold itself together long enough to be studied in any traditional sense. Scientists detect these elements not by observing the atom directly, but by tracking the chain of lighter atoms it leaves behind as it decays, like identifying a firework by the pattern of sparks it produces.
Because so few atoms are ever created (sometimes literally one at a time), measuring properties like melting point, density, or chemical reactivity through normal experiments is impossible. Much of what we know about superheavy element behavior comes from theoretical calculations rather than direct measurement.
Unexpected Chemistry at the Extremes
One of the most fascinating things about superheavy elements is that they don’t always behave the way the periodic table predicts. In lighter elements, you can look at an element’s column on the table and make a reasonable guess about its properties. Mercury is a liquid metal, so you might expect copernicium (element 112), which sits directly below it, to behave similarly.
It probably doesn’t. Electrons in superheavy atoms move so fast that Einstein’s theory of relativity comes into play. At these speeds, electrons behave as though they have more mass, which changes how tightly they orbit the nucleus and how they interact with other atoms. As far back as 1975, physicist Kenneth Pitzer predicted that copernicium would actually be volatile and chemically inert, more like a noble gas than a metal, because relativistic effects cause its outermost electrons to hug the nucleus much more tightly than expected. This gives copernicium an atomic radius even smaller than cadmium, an element 68 spots lighter on the periodic table.
Flerovium (element 114) shows a similar quirk. Relativistic effects split its outermost electron shell in a way that creates a closed, stable configuration, again making it far less reactive than you’d expect from its position in the carbon group. Element 118, oganesson, belongs to the noble gas column but likely has an unusually diffuse outer electron shell, meaning it may behave differently from lighter noble gases like neon or argon. These relativistic surprises are one of the main reasons physicists pursue superheavy element research: each new element tests whether our understanding of atomic structure holds up under extreme conditions.
The Search for the Island of Stability
Not all superheavy elements are expected to be equally unstable. Theoretical physics predicts that certain combinations of protons and neutrons create “magic numbers” that make a nucleus much more resistant to decay, similar to how filled electron shells make noble gases chemically stable. A cluster of these magic-number nuclei, sometimes called the island of stability, is predicted to exist somewhere around elements 114 to 126.
If this island exists, some superheavy isotopes might last minutes, hours, or potentially much longer instead of milliseconds. That would change everything about how scientists study them, potentially allowing direct chemical experiments for the first time. Reaching this island is a major motivator behind efforts to synthesize elements 119 and 120.
The Race to Element 119
No one has yet created an element beyond 118. It’s not for lack of trying. A team at GSI Darmstadt in Germany spent four months firing titanium-50 beams at targets of berkelium-249 and californium-249, searching for elements 119 and 120. Neither was detected. The berkelium target gradually decayed into californium during the experiment, which allowed both searches to run simultaneously, but the probability of fusion was simply too low to produce a single atom in that timeframe.
Multiple laboratories around the world are now competing to be first. RIKEN in Japan, the Joint Institute for Nuclear Research in Russia, and facilities in the United States and Germany all have active programs. Creating element 119 would be a landmark achievement because it would begin the eighth row of the periodic table, entering completely uncharted chemical territory where relativistic effects on electron behavior become even more dramatic.
How a New Element Becomes Official
Claiming a new element isn’t enough. The discovery must survive a rigorous verification process run jointly by two international scientific bodies: IUPAC (the International Union of Pure and Applied Chemistry) and IUPAP (the International Union of Pure and Applied Physics). A joint working group examines all the evidence, contacts every laboratory involved, and publishes a technical report that goes through peer review.
The report must clearly state whether the claim meets the established criteria for discovery and assign credit to the responsible team. It then needs formal approval from IUPAC’s Inorganic Chemistry Division and the executive committees of both IUPAC and IUPAP. Only after all of that are the discoverers invited to propose a name and symbol. That proposal goes through yet another round of review before the IUPAC Council gives final ratification. The entire process can take years. Oganesson, for instance, was first created in 2002 but wasn’t officially named until 2016.
Why Bother Making Atoms That Vanish Instantly
It’s a fair question. These experiments cost millions of dollars, take years, and produce atoms that often exist for less time than it takes to blink. The value lies in what these atoms reveal about fundamental physics. Every new superheavy element tests the limits of nuclear theory, forces physicists to refine models of how protons and neutrons interact, and probes whether the periodic table’s organizing principles hold up at the extremes. The relativistic effects that distort superheavy element chemistry provide real-world tests of quantum mechanics and special relativity working together in ways that can’t be studied any other way.
There’s also a deeper structural question at stake: does the periodic table have an end? At some point, nuclei may become so large that no combination of protons and neutrons can hold together even briefly. Finding that boundary, or discovering that the island of stability extends it further than expected, would reshape our understanding of matter itself.