Moscovium (Mc)
Element 115 · Post-transition metal · atomic mass [290] u · group 15, period 7
Electron shells: 2, 8, 18, 32, 32, 18, 5
Moscovium decays within a fraction of a second into nihonium. It became briefly famous through a widely debunked UFO conspiracy theory.
Long before it was made, "element 115" was a staple of UFO folklore.
- Atomic number
- 115
- Atomic mass
- [290] u
- Electron configuration
- [Rn] 7s² 7p³ 5f¹⁴ 6d¹⁰
- Group · period · block
- 15 · 7 · p
- Oxidation states
- +1, +3
- Electronegativity
- Not measured
- Melting point
- —
- Boiling point
- —
- Density
- Not measured
- State at 20 °C
- Unknown
- Appearance
- Unknown; presumed metallic
- Discovered
- Joint Institute for Nuclear Research and Lawrence Livermore, 2003
115 protons, and 115 electrons when neutral
Mass number of the longest-lived isotope — no standard atomic weight exists
Predicted, not measured
Pnictogens
What Moscovium is used for
- Scientific research only
Atomic structure of Moscovium
A neutral moscovium atom has 115 protons and 115 electrons. Its most common isotope carries about 175 neutrons, which is where the mass number 290 comes from. Change the neutron count and you have a different isotope of moscovium; change the proton count and you have a different element entirely.
Those electrons fill shells from the inside out: 2, 8, 18, 32, 32, 18, 5. In orbital notation that is [Rn] 7s² 7p³ 5f¹⁴ 6d¹⁰, leaving 5 valence electrons in the outer shell — the ones that do the chemistry.
3D electron orbitals
See where Moscovium's electrons actually are — a cloud of 26,000 points sampled from the probability density |ψ|², not a cartoon of a lobe.
Where Moscovium sits in the periodic table
Metals to the right of the d-block. Softer, lower-melting and more brittle than the transition metals, with more covalent character in their bonding.
- Directly above: Bismuth — same group, so similar chemistry with a smaller atom.
- One proton lighter: Flerovium.
- One proton heavier: Livermorium.
Discovery and naming
Moscovium was discovered by Joint Institute for Nuclear Research and Lawrence Livermore in 2003. Its name comes from Moscow, which is also why its symbol (Mc) does not match its English name.
Every isotope of moscovium is radioactive, so it has no standard atomic weight. Periodic tables show the mass number of its longest-lived isotope in square brackets instead.
Keep exploring
Atomic weight from IUPAC/CIAAW; physical properties from PubChem (US National Library of Medicine). Values that have never been measured are shown as “not measured” rather than estimated.
Related Calculators
Frequently Asked Questions
What is the atomic mass of Moscovium?
Moscovium has no stable isotope, so it has no standard atomic weight. Periodic tables instead show 290 in square brackets — the mass number of its longest-lived isotope.
How many protons, neutrons and electrons does Moscovium have?
Moscovium has 115 protons, because the atomic number is the proton count and that is what makes an atom Moscovium at all. A neutral Moscovium atom has the same number of electrons, 115. The neutron count varies by isotope; the most common one has about 175, since 290 − 115 = 175.
What is the electron configuration of Moscovium?
The electron configuration of Moscovium is [Rn] 7s² 7p³ 5f¹⁴ 6d¹⁰, though for an element this heavy the configuration is predicted from theory rather than measured. Its electrons are arranged 2, 8, 18, 32, 32, 18, 5 across 7 shells.
Is Moscovium a metal?
Yes. Moscovium is classified as a post-transition metal, on the metallic side of the table.
What group and period is Moscovium in?
Moscovium is in group 15 (the pnictogens), period 7, in the p-block. The group is its column and the period is its row.
What is Moscovium used for?
Scientific research only. Moscovium decays within a fraction of a second into nihonium.
Who discovered Moscovium, and where does its name come from?
Moscovium (Mc) was discovered by Joint Institute for Nuclear Research and Lawrence Livermore in 2003. The name comes from Moscow.
Is Moscovium radioactive?
Yes. Every isotope of Moscovium is radioactive — it has no stable form at all, which is why the periodic table shows its mass in square brackets rather than as a standard atomic weight.