Element identity
Element 118 identity and isotope/decay evidence are experimental/evaluated.
Atomic / electronic interpretation
Electronic structure and many chemical expectations are theory-led in an extreme relativistic regime.
Bulk state / properties
Some bulk behavior is predicted rather than measured; the interface labels that distinction explicitly.
Measured macroscopic structure
No ordinary macroscopic crystal sample has been measured.
Geography
Research/discovery geography replaces natural-resource geography.
The lens describes evidence status, not confidence theatre. “Unknown” is kept unknown, and teaching schematics are not presented as direct measurements.
Oganesson (Og)
Explore the heaviest confirmed element: a superheavy Group 18 atom known from only a few nuclear-decay events, with a millisecond-scale lifetime and many chemical and physical properties that must still be predicted using relativistic quantum theory.
Oganesson atomic number, mass, electron configuration and evidence level
Oganesson: quick answers
How many protons, neutrons and electrons does oganesson have?
Oganesson’s atomic number is 118, so every oganesson atom has 118 protons, and a neutral atom also has 118 electrons. Oganesson has no stable isotopes, so the neutron count depends on the isotope: oganesson-294, featured on this page, has 176 neutrons.
What is the symbol for oganesson?
The chemical symbol for oganesson is Og.
Is oganesson a solid, liquid or gas at room temperature?
Oganesson has only been made a few atoms at a time; calculations predict it would be a solid at room temperature, unlike the other noble gases.
What family (group) is oganesson in?
Oganesson is a noble gas (predicted), in group 18, period 7 of the periodic table.
What is the electron configuration of oganesson?
The ground-state electron configuration of oganesson is [Rn] 5f¹⁴ 6d¹⁰ 7s² 7p⁶. This is a predicted configuration; it has not been measured.
From atomic number to chemistry
Read these as a chain of causes, not as isolated facts. Each step links to the concept hub if you want the underlying idea explained.
The proton count defines element 118 and creates an extreme nuclear charge for its electrons.
The bracketed 294 is an isotope mass number, not a conventional standard atomic weight.
A filled nominal valence shell places Oganesson in Group 18, but very strong relativistic effects matter.
It occupies the noble-gas column, yet simple extrapolation from radon is not enough to predict all behavior.
Only a few short-lived nuclei have been observed, so ordinary macroscopic measurements are unavailable.
Oganesson closes Period 7 and sits beneath radon in Group 18
The Group 18 placement comes from its proton number and electron configuration, but the chemistry is not expected to be a simple scaled-up version of xenon or radon. At Z = 118, relativistic effects become large enough to blur familiar periodic trends.
Oganesson Visual Lab
Decode the Og tile, rotate a ²⁹⁴Og educational nucleus, inspect shell populations, explore qualitative 7s/7p probability shapes and see why relativistic theory predicts behavior unlike an ordinary noble gas.
Seven facts - but not seven equal certainties
Oganesson in one minute
It is element 118. That makes it the heaviest confirmed chemical element and the endpoint of Period 7.
No bottle of oganesson exists. It is created atom-by-atom and disappears by radioactive decay almost immediately.
Group 18 does not guarantee “ordinary noble gas” behavior. Strong relativistic effects change the outer-electron physics.
Solid at room temperature is a theoretical prediction. The best-known high-level calculations place melting near 325 K, not a measured laboratory value.
Unknown is a valid scientific answer. Many bulk properties cannot yet be measured and should not be filled with invented numbers.
2 · 8 · 18 · 32 · 32 · 18 · 8 electrons
The simple 7p⁶ label looks noble-gas-like, but at Z = 118 strong spin-orbit and relativistic effects alter orbital energies, electron localization and polarizability. The shell rings above are only a counting aid.
Alpha decay changes both atomic number and mass number
⁴He nucleus emitted
Alpha decay removes two protons and two neutrons from the parent nucleus. The decay chain, rather than bulk chemical testing, is one of the key ways superheavy nuclei are identified experimentally.
Oganesson: no measured macroscopic crystal lattice
A very heavy atom changes the familiar orbital story
The 7s probability distribution is drawn as a spherical cloud. In oganesson, relativistic effects strongly influence the energies and radial behavior of the outer electrons, so this is a qualitative teaching shape rather than a scale drawing.
High-level calculations predict such strong spin-orbit splitting and relativistic changes that the outer-electron localization becomes unusually smooth compared with lighter noble gases. This does not mean the atom literally becomes a classical electron gas; it means the familiar shell-localization pattern is strongly blurred in the calculated localization function.
What is oganesson actually useful for?
Oganesson has no practical material use because atoms exist for far too short a time. Its value is scientific: each detected atom tests nuclear physics, relativistic quantum chemistry and the limits of the periodic table.
A scientific result can be only a few detected atoms
Oganesson is created in nuclear-reaction experiments and identified through its decay pattern. There is no macroscopic specimen to photograph, weigh or use as an engineering material.
Why can a “noble gas” be predicted to be solid and less noble?
For lighter Group 18 elements, weak attractions between closed-shell atoms lead to very low boiling points. Oganesson sits in the same column, but the nuclear charge is so large that relativity is no longer a small correction: it reshapes the electronic structure and strengthens interactions in ways simple periodic extrapolation misses.
Enormous nuclear charge
With 118 protons, the electric field experienced by inner and outer electrons is extreme. Electron motion must be treated relativistically for a defensible calculation.
Strong spin-orbit splitting
Relativistic coupling splits p-electron states strongly. The 7p shell cannot be understood as a simple copy of the 6p shell in radon.
Large polarizability
Calculations predict an unusually deformable outer electron cloud. Greater polarizability can strengthen dispersion interactions between Og atoms.
Stronger condensed-phase attraction
Relativistic many-body interactions in theoretical simulations raise the predicted melting point enough that solid Og near room temperature becomes plausible.
Less textbook “noble” behavior
Theoretical studies predict electronic properties that depart from the inert-gas pattern. That is a prediction about isolated atoms and hypothetical bulk matter, not an experimentally tested bottle of Og chemistry.
Periodicity has limits
The periodic table remains the organizing framework, but at superheavy atomic numbers relativistic and nuclear effects become strong enough that simple down-a-group extrapolation can fail.
Oganesson physical, atomic and nuclear properties
For Oganesson, the most useful data table is one that says not only what a value is, but how we know it. Blank or unknown fields are retained rather than filled by unsupported extrapolation.
| Atomic number | 118 | Experimentally established element identity |
|---|---|---|
| Symbol | Og | IUPAC-approved symbol |
| Periodic-table mass display | [294] | No standard atomic weight; bracketed isotope mass number is used |
| Group / Period / Block | 18 / 7 / p | IUPAC periodic-table placement |
| Electron configuration | [Rn] 5f¹⁴ 6d¹⁰ 7s² 7p⁶ | Reference theoretical/atomic-structure description |
| Shell populations | 2, 8, 18, 32, 32, 18, 8 | Teaching count from the configuration |
| Reference isotope | ²⁹⁴Og | Observed superheavy isotope used in the principal discovery chain |
|---|---|---|
| Protons / neutrons | 118 / 176 | For ²⁹⁴Og |
| Half-life | ≈0.7 ms | Evaluated order-of-magnitude value; event statistics are very limited |
| Primary decay | Alpha decay | ²⁹⁴Og → ²⁹⁰Lv + α |
| Stable isotopes | 0 | No stable Oganesson isotope is known |
| Natural abundance | None | Artificially produced; no natural terrestrial inventory is known |
| State near 293 K | Predicted solid | High-level relativistic condensed-phase theory; not direct observation |
|---|---|---|
| Predicted melting point | 325 ± 15 K | Smits et al. 2020; computational prediction |
| Predicted normal boiling point | 450 ± 10 K | Smits et al. 2020; computational prediction |
| Measured melting / boiling | Unknown | No macroscopic sample exists for measurement |
| Measured density | Unknown | Bulk density predictions are model-dependent |
| Measured crystal structure | Unknown | Any lattice used in simulation is a model, not an observed crystal |
| Relativistic treatment | Essential | High-Z electron structure cannot be treated accurately as a small nonrelativistic correction |
|---|---|---|
| Valence localization | Predicted strongly smeared | Jerabek et al. 2018 electron-localization calculations |
| Polarizability | Predicted unusually large | Contributes to stronger interatomic attraction than simple noble-gas extrapolation |
| Electron affinity | Small positive value predicted | Unlike the simplest inert-gas expectation; theoretical result |
| Common oxidation states | Not experimentally established | Proposed values are theoretical and model-dependent |
| Bulk conductivity | Not measured | Solid-state electronic behavior remains theoretical |
| Group | 18 | Same column as He, Ne, Ar, Kr, Xe and Rn |
|---|---|---|
| Valence-shell pattern | 7s² 7p⁶ | Closed-shell reference configuration |
| Expected volatility | Much lower than simple extrapolation | Relativistic many-body interactions strengthen condensation in theory |
| Room-temperature phase | Predicted solid | Unlike lighter noble gases under ordinary conditions |
| Chemical inertness | Not directly tested | “Noble gas” is a group classification, not proof of identical reactivity |
| Trend confidence | Low for naive extrapolation | Relativistic effects grow strongly at the bottom of the periodic table |
| Name / symbol / Z | High confidence | IUPAC-approved and discovery verified |
|---|---|---|
| Decay chain | Experimental but sparse | Only very small numbers of nuclei are available |
| Half-life | Evaluated with large uncertainty | Statistical uncertainty is unavoidable with few events |
| Melting / boiling | Theoretical prediction | Useful high-level result, not direct measurement |
| Detailed chemistry | Theoretical prediction | One-atom-at-a-time chemistry has not been feasible for such a short-lived isotope |
| Unknown fields | Intentionally preserved | Element Lookup does not invent data to make a table look complete |
Xenon, radon and oganesson: where the noble-gas trend stops being simple
The comparison is qualitative because many Oganesson quantities are not measured. The key learning point is that increasing atomic number strengthens relativistic effects so strongly that “just continue the trend” becomes unreliable.
| Evidence | Measured gas at room temperature |
|---|---|
| Valence shell | 5s² 5p⁶ |
| Evidence | Measured radioactive gas |
|---|---|
| Valence shell | 6s² 6p⁶ |
| Evidence | Predicted solid near room temperature |
|---|---|
| Valence shell | 7s² 7p⁶ · extreme relativistic regime |
Predicted Oganesson state at temperature
This slider is intentionally different from Carbon, Gold or Uranium. Oganesson has no experimentally measured bulk melting or boiling point, so the phase path below visualizes one published high-level theoretical prediction - not a laboratory phase diagram.
melt band325 K
prediction340 K440-460 K
boil band1000 K
At 293 K, the 2020 high-level model predicts solid Oganesson. No bulk Og sample has existed long enough for a direct state, melting-point or boiling-point measurement.
Published prediction used here: melting 325 ± 15 K and normal boiling 450 ± 10 K. Near each uncertainty band, the explorer shows a transition region instead of pretending the boundary is exact.Where on Earth was Oganesson made and studied?
There is no natural-occurrence or mining map for Oganesson. The honest geographic story is the collaboration behind its creation and verification: synthesis experiments at JINR in Dubna, with Lawrence Livermore National Laboratory as a discovery collaborator.
From decay chains to a formally named element
Three element-118 decay chains formed the early evidence set
The published discovery record describes an initial 2002 event followed by two additional consistent events in the 2005 experiment. The collaboration reported the combined decay-chain evidence in 2006. Different institutional summaries emphasize the 2005 confirmation experiment differently, so this timeline points readers to the primary literature below.
Discovery results published
The collaboration reported synthesis of element 118 in Physical Review C, providing decay-chain evidence for the new superheavy nucleus.
IUPAC/IUPAP verify the discovery claim
The Joint Working Party determined that the Dubna-Livermore collaboration had fulfilled the criteria for discovery of element 118.
Oganesson (Og) becomes official
IUPAC approved the name Oganesson and symbol Og, honoring Yuri Oganessian for pioneering work on transactinoid and superheavy elements.
How can scientists discover an atom that vanishes in a millisecond?
The answer is not by collecting a visible sample. Superheavy-element experiments look for a small number of nuclei and then reconstruct their identity from characteristic sequences of radioactive decay detected after a nuclear-reaction event.
Heavy-ion reaction
A calcium-48 beam was directed at a californium-249 target in the discovery experiment.
Rare fusion event
Very rarely, the colliding nuclei form a superheavy compound system that can survive long enough to become an element-118 nucleus.
Separation and detection
The experiment separates candidate reaction products from the enormous background of particles that did not form the desired nucleus.
Decay-chain fingerprint
Successive alpha decays connect the new parent to daughter nuclei, providing a nuclear fingerprint rather than a macroscopic chemical sample.
Oganesson-294 and the edge of known nuclei
The reference Oganesson isotope
Oganesson-294 is the isotope associated with the principal discovery chain. Its lifetime is only on the order of a millisecond, so it decays before conventional bulk chemistry or material measurements can be performed.
“Heavier” does not always mean “instantly less stable” in a simple way
The nuclear shell model predicts regions where particular proton and neutron combinations could gain extra stability relative to nearby superheavy nuclei. Oganesson research helps map the approach toward that proposed island of stability, but ²⁹⁴Og itself is still extremely short-lived.
The phrase “island of stability” does not mean there is a known stable element beyond Oganesson. It describes a theoretical region of comparatively enhanced nuclear lifetimes.
What do we know, infer and predict about Oganesson?
Observed directly
Decay events from nuclei assigned to element 118, their position in a nuclear decay chain, and the experimental collaboration that produced them.
Evaluated from sparse nuclear data
Isotope masses, half-life estimates and decay properties compiled from very small numbers of events with correspondingly large uncertainties.
Predicted by relativistic theory
Electron localization, polarizability, possible reactivity, hypothetical bulk state, melting point, boiling point and other macroscopic properties.
Still unknown experimentally
Measured bulk density, appearance, crystal structure, electrical properties and ordinary laboratory chemistry of a macroscopic sample.
Oganesson quiz
1. Why is [294] shown in brackets?
2. What is measured for bulk Oganesson?
3. The ≈325 K melting value is…
4. Oganesson is in which group?
5. ²⁹⁴Og contains how many neutrons?
6. Why are relativistic effects important?
Oganesson questions students commonly ask
Each answer separates the direct conclusion from the experimental or theoretical evidence behind it.
Is oganesson a gas at room temperature?
Short answer: Probably not according to a major high-level theoretical study, but this has not been measured.
Smits and co-workers predicted a melting point around 325 ± 15 K, placing 293 K below the predicted melt and therefore in a solid region. Other compilations may summarize the expected state differently, which is why Element Lookup labels this as theory rather than a settled bulk measurement.
Key point: Group 18 placement does not by itself determine an experimentally known room-temperature phase for oganesson.
Why is oganesson called a noble gas if it may be solid?
Short answer: “Noble gas” is a periodic-table group classification, not a promise that every member must be gaseous at room temperature.
Oganesson has the Group 18 valence pattern, but its enormous nuclear charge produces strong relativistic electronic effects. Those effects change polarizability, interatomic attraction and predicted bulk behavior compared with the lighter noble gases.
Key point: Chemical group and physical state are different kinds of classification.
How many protons, neutrons and electrons does oganesson-294 have?
Short answer: 118 protons, 176 neutrons and 118 electrons for a neutral ²⁹⁴Og atom.
Atomic number gives the proton count. Subtracting 118 from mass number 294 gives 176 neutrons, and a neutral atom has the same number of electrons as protons.
Key point: Atomic number defines oganesson; mass number identifies the isotope.
What is the half-life of oganesson?
Short answer: Oganesson-294 lives for only about a millisecond.
Evaluated values are around 0.7 ms and carry substantial uncertainty because they are based on very small numbers of detected nuclei. That short lifetime is one reason ordinary chemistry and bulk-property measurements are extraordinarily difficult.
Key point: Half-life statements must name the isotope.
Does oganesson occur naturally?
Short answer: No natural terrestrial occurrence is known.
Oganesson has been produced artificially in nuclear-reaction experiments. A map of mines or natural deposits would therefore be misleading, so the page uses discovery and research context instead.
Key point: Synthetic-element geography should show research history, not invented natural deposits.
Does oganesson have any practical uses?
Short answer: No practical material uses are known.
The atoms decay far too quickly for ordinary material applications. Its importance is fundamental research: nuclear stability, decay models, superheavy-element synthesis, relativistic electronic structure and the limits of periodic trends.
Key point: Scientific value does not require a commercial material use.
Why does Element Lookup leave some oganesson properties as “unknown”?
Short answer: Because unknown is more accurate than an invented number.
The project requires authoritative provenance for scientific data. Theoretical predictions are useful and may be shown when well supported, but they are visibly separated from direct experimental measurements of bulk matter.
Key point: Predicted, measured and unknown are different evidence states.
Where the Oganesson information comes from
- IUPAC — discovery verification and official name/symbol record for element 118
- PubChem — evaluated/compiled Oganesson isotope mass, decay and half-life context
- Royal Society of Chemistry — Group 18 / Period 7 / p-block classification; measured bulk melting, boiling and density fields remain unknown
- Lawrence Livermore National Laboratory — institutional account of the 2005 confirmation experiment and 2006 discovery publication
- Jerabek et al., Physical Review Letters 120, 053001 (2018) — relativistic electron/nucleon localization and large-polarizability prediction
- Smits et al., Angewandte Chemie International Edition (2020) — high-level theoretical melting and boiling predictions used in the prediction-only temperature explorer
Questions to ask next about Oganesson
A good element lesson should lead to the next useful question, not end after a list of facts.
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