115Mc

Moscovium

Unknown propertiesunknownblock p

A superheavy element made by firing calcium at americium, whose decay chain was itself the confirming evidence for discovering tennessine.

Atomic number115
Mass number (longest-lived isotope)290 g/mol
This element has no stable isotope, so it has no standard atomic weight. The figure above is the mass number of its longest-lived isotope — a convention, not a measurement of a natural mixture.
Group · period15 · 7
Electron configuration[Rn] 5f¹⁴ 6d¹⁰ 7s² 7p³

About Moscovium

Moscovium was first made at Dubna in 2003 by bombarding americium-243 with calcium-48, and it was formally recognised alongside nihonium, tennessine and oganesson in 2015, completing the seventh row of the periodic table. It is named for the Moscow region, home of the Joint Institute for Nuclear Research. Its alpha-decay chain runs down through nihonium and roentgenium, and identifying those daughters is how several superheavy claims were cross-checked. No chemistry has ever been attempted; theory predicts it would be a fairly reactive metal under bismuth, possibly with a stable +1 state driven by the inert-pair effect running at full relativistic strength, but nothing is measured, so no category is claimed.