Unknown propertiesElement 115 · p-block

Moscovium (Mc)

Moscovium (Mc), element 115, is a synthetic superheavy element whose chemical properties have not been measured; its most stable known isotope has mass number 290. Only a few atoms have ever been made, so its bulk properties are predictions.

115McMoscovium[290]

Atomic number

115

protons

Atomic weight

[290]

most stable isotope

Melting point

—

Boiling point

—

Density

13.5 g/cm³

predicted

Electronegativity

—

Pauling scale

State at 25 °C

Unknown

predicted solid

Discovered

2003

Russia (Dubna)

Moscovium at a glance

Identity

Symbol	Mc
Atomic number (Z)	115
Atomic weight	[290] mass number of the most stable isotope
Category	Unknown properties
Group	15 — pnictogens (nitrogen group)
Period	7
Block	p-block
CAS number	54085-64-2

Atomic properties

Electron configuration	[Rn] 5f¹⁴ 6d¹⁰ 7s² 7p³ Full: 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 4f¹⁴ 5s² 5p⁶ 5d¹⁰ 5f¹⁴ 6s² 6p⁶ 6d¹⁰ 7s² 7p³
Electrons per shell	2, 8, 18, 32, 32, 18, 5
Covalent radius	162 pm

Physical properties

State at 25 °C	Unknown (predicted solid)
Density	13.5 g/cm³ (predicted)

Isotopes & abundance

Natural occurrence	Synthetic
Radioactive	Yes
Most stable isotope	²⁹⁰Mc — half-life 840 ms
Known isotopes	6

Atomic weights: CIAAW Abridged Standard Atomic Weights 2024. Other properties: standard reference compilations, checked October 2026; predicted values are marked.

Moscovium electron configuration

Moscovium has 115 electrons. Written in short form, its ground-state configuration is [Rn] 5f¹⁴ 6d¹⁰ 7s² 7p³ — the electrons of the noble gas radon, plus 5f¹⁴ 6d¹⁰ 7s² 7p³.Written out in full: 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 4f¹⁴ 5s² 5p⁶ 5d¹⁰ 5f¹⁴ 6s² 6p⁶ 6d¹⁰ 7s² 7p³.

As a member of group 15 it has 5 valence electrons in its outer shell (shell 7), which largely decide its chemistry.

5f↑↓↑↓↑↓↑↓↑↓↑↓↑↓

6d↑↓↑↓↑↓↑↓↑↓

7s↑↓

7p↑↑↑

Discovery and name

Discovered

2003 — Joint Institute for Nuclear Research with Lawrence Livermore National Laboratory · Russia (Dubna).

Name

Moscow Oblast, the region of Dubna.

Known for

Made by bombarding americium-243 with calcium-48 ions; it decays in a fraction of a second.

Isotopes of moscovium

Moscovium has no stable isotopes and does not occur naturally in significant amounts. Its longest-lived known isotope is:

Isotope	Protons	Neutrons	Half-life
²⁹⁰Mc	115	175	840 ms

6 isotopes of moscovium are known in our data set (half-lives as published in nuclear data tables).

Moscovium compared with group 15

The other elements in group 15 (pnictogens (nitrogen group)), from top to bottom of the table:

Element	Z	Atomic weight	Melting point	Boiling point	Density	Electronegativity
Nitrogen	7	14.007	-210 °C	-196 °C	1.2506 g/L	3.04
Phosphorus	15	30.974	44 °C	281 °C	1.823 g/cm³	2.19
Arsenic	33	74.922	—	614 °C	5.75 g/cm³	2.18
Antimony	51	121.76	631 °C	1,587 °C	6.68 g/cm³	2.05
Bismuth	83	208.98	271 °C	1,564 °C	9.79 g/cm³	2.02
Moscovium	115	[290]	—	—	13.5 g/cm³ (pred.)	—

Frequently asked questions

4 answers

What is the atomic mass of moscovium?

Moscovium has no stable isotopes, so it has no standard atomic weight. Periodic tables show [290], the mass number of its most stable known isotope.

How many protons, neutrons and electrons does moscovium have?

A neutral moscovium atom has 115 protons and 115 electrons. Its most stable isotope, moscovium-290, has 175 neutrons.

What is the electron configuration of moscovium?

[Rn] 5f¹⁴ 6d¹⁰ 7s² 7p³ (in full: 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 4f¹⁴ 5s² 5p⁶ 5d¹⁰ 5f¹⁴ 6s² 6p⁶ 6d¹⁰ 7s² 7p³).

Who discovered moscovium?

2003 — Joint Institute for Nuclear Research with Lawrence Livermore National Laboratory (Russia (Dubna)).