Moscovium
Moscovium is the name of a synthetic superheavy element in the periodic table that has the symbol Mc and has the atomic number 115. It is an extremely radioactive element; its most stable known isotope, moscovium-289, has a half-life of only 220 milliseconds. It is also known as eka-bismuth or simply element 115.
Identity
- Atomic mass
- 289 u
- Category
- Post-transition metals
- Group
- 15
- Period
- 7
- Block
- p
- Oxidation States
- Limited experimental data
- Phase (25 °C)
- Solid
Electronic Structure
- Electron configuration
- 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 4f14 5d10 6p6 7s2 5f14 6d10 7p3
- Short configuration
- *[Rn] 5f14 6d10 7s2 7p3
- Electrons per shell
- 2, 8, 18, 32, 32, 18, 5
- Electronegativity (Pauling)
- —
- Electron affinity
- 35.3 kJ/mol
- 1st ionization energy
- —
Physical properties
- Melting point
- 396.9 °C (670 K)
- Boiling point
- 1126.8 °C (1400 K)
- Density
- 13.5 g/cm³
- Molar heat capacity
- —
Chemical behavior of moscovium
Moscovium is a superheavy transactinide with symbol Mc and atomic number 115, belonging to group 15 (pnictogens) below bismuth, antimony and arsenic. Its predicted ground-state electron configuration is [Rn] 5f¹⁴ 6d¹⁰ 7s² 7p¹/₂² 7p₃/₂¹. Unlike bismuth, which prefers trivalent +3 state, moscovium possesses a single electron in the destabilized and easily ionizable 7p₃/₂ orbital, which strongly favors the monovalent +1 oxidation state (Mc⁺) in aqueous solution and volatile halides, exhibiting a marked reactive post-transition metal behavior.
Reactivity
Mc + HCl → McCl + 1/2 H₂ (predicted)
It would form monovalent volatile and stable moscovium monochloride in acidic solution, analogous to thallium(I) halides.
Mc + H₂O → McOH + 1/2 H₂ (predicted)
It would react with water forming very soluble and strongly alkaline moscovium monohydroxide.
Mc (gas) + SiO₂ / Au → Mc (adsorbed)
Initial thermochromatographic experiments indicate it adsorbs more strongly on quartz and gold than flerovium and copernicium.
Notable compounds
| Compound | Formula | Use or importance |
|---|---|---|
| Moscovium monochloride | McCl | Monovalent halide predicted by thermodynamic models as the most accessible gaseous species for experiments |
| Moscovium monohydroxide | McOH | Theoretical monovalent basic compound predicted with high aqueous solubility and alkaline properties analogous to CsOH |
| Moscovium trifluoride | McF₃ | Quantum-modeled trivalent halide, unstable against spontaneous reduction to monohalide |
Electron shell distribution
View in the atom builderIsotopes
All moscovium isotopes are radioactive and of artificial origin, with five nuclides known with masses between 287 and 291. The most durable isotope is moscovium-290 (²⁹⁰Mc), with a half-life of approximately 0.65 to 0.8 seconds decaying by alpha emission to nihonium-286. The most studied isotope is moscovium-288 (²⁸⁸Mc, half-life of about 0.16 to 0.2 seconds), whose cascade of consecutive nuclear decays is the main channel for discovering daughter superheavy nuclides.
Occurrence and production
It does not exist naturally on Earth nor in the detectable cosmos. It is generated atom by atom in high-energy particle accelerators through the hot nuclear fusion reaction bombarding radioactive americium-243 targets with accelerated calcium-48 projectiles at the Dubna Institute (Russia). Its synthesis rate is barely a few individual atoms per week of uninterrupted irradiation.
History and origin of the name
It was first synthesized in August 2003 at the Joint Institute for Nuclear Research (JINR) in Dubna (Russia) in collaboration with Lawrence Livermore National Laboratory of the United States. After being independently confirmed at Germany's GSI laboratory in 2013 and at Berkeley in 2015, IUPAC officially approved in November 2016 the name '[moscovium]' in honor of the Moscow oblast, geographic region where the Dubna scientific city is located.
Applications and relevance of moscovium
Uses of the element
It lacks technological, industrial or commercial applications since it is produced in atomic units and disintegrates in fractions of a second. Its study has enormous scientific significance to contrast nuclear physics theoretical predictions about stability against spontaneous fission and unravel how relativity favors monovalent states in group 15.
Uses of its compounds
No compounds are produced at visible scale; its chemical properties are explored through automated helium gas transport systems and single-atom chromatography.
Health, safety and environment
Biological role
It has no biological role in nature nor interacts with living beings since it exists exclusively in ultra-high vacuum conditions in accelerators.
Safety
Radiological protection concerns exclusively operators facing the heavy ion beam and radioactive americium-243 target handling.
Environment
It generates no ecological waste with environmental impact since produced atoms are counted in units and decay immediately.
Frequently asked questions about Moscovium
Why was moscovium baptized in honor of the Moscow oblast in 2016?
The Joint Institute for Nuclear Research (JINR) is located in Dubna, on the banks of the Volga River, within the Moscow oblast administrative region. To commemorate more than half a century of pioneering transuranium and transactinide element discoveries at its facilities, Russian and American scientists proposed 'moscovium'. IUPAC ratified the name in 2016, inscribing the historic Moscow region into the periodic table.
Why was element 115 linked to UFO stories?
Element 115 appeared in popular accounts about supposed extraterrestrial propulsion systems before its laboratory synthesis was confirmed. However, those claims were not backed by scientific evidence. Real moscovium is a superheavy element produced atom by atom, radioactive and of very short life. It has not been demonstrated that it allows obtaining extraordinary energy nor that it has the properties described in those stories.
What would happen if a moscovium sample could be observed?
It is not possible to gather a visible moscovium sample since it is produced atom by atom and its isotopes decay rapidly. Therefore, it has not been directly observed how a piece of this element would react with air or water. Scientists use theoretical calculations and comparisons with other group elements to estimate its behavior, but those predictions are not direct observations.
What challenges does measuring moscovium atom interaction present when they live half a second?
With a half-life of barely six hundred milliseconds, the moscovium atom must be extracted from the reaction target, decelerated in atmospheric helium gas, transported through a ten-meter millimeter capillary and injected into a detector cell in less than two hundred milliseconds. Nuclear chemists use laminar gas flows at supersonic speeds to complete the chemical reaction before the atom decays.
Why does the monovalent oxidation state dominate moscovium's predicted chemistry?
In lighter group 15 elements (such as phosphorus, arsenic or bismuth), dominant oxidation states are +3 and +5 by sharing their three p electrons. In moscovium, relativistic spin-orbit splitting separates the 7p subshell into two quantum levels: the closed 7p₁/₂ level with two electrons, and a destabilized 7p₃/₂ orbital with a single electron. This solitary electron is easily removed, strongly favoring the monovalent Mc⁺ state.
How did the americium-243 target allow synthesizing over a hundred moscovium atoms?
Americium-243 possesses ninety-five protons and one hundred forty-eight neutrons. Upon colliding with doubly magic calcium-48 projectiles (twenty protons), the exact sum gives one hundred fifteen protons. This nuclear combination presents an exceptionally favorable fusion cross-section compared to other transactinides, allowing Dubna and Germany laboratories to produce over a hundred moscovium atoms across various experiments.
How does moscovium-288 decay through a cascade of five alpha decays to dubnium?
When a moscovium-288 nucleus is created at the cyclotron target, it initiates a very high-energy radioactive cascade: it emits an alpha particle in two tenths of a second transforming into nihonium-284, this decays alpha to roentgenium-280, then to meitnerium-276, to bohrium-272 and finally to dubnium-268. This uninterrupted sequence of five alpha transmutations ends with dubnium fission after more than twenty-four hours of survival.
Main sources consulted: PubChem, Royal Society of Chemistry, NIST, IUPAC. Last revision: November 2026.