Promethium

Atomic number

61

Atomic mass (u)

144.91276

Category

Lanthanide

Standard state

Solid

Melting point

1041.85 °C (1315 K)

Boiling point

2999.85 °C (3273 K)

Density (g/cm³)

7.26

Electronegativity (Pauling)

Not reported in this source

Electron configuration

[Xe]6s2 4f5

Oxidation states

+3

Atomic radius (pm)

236

First ionization energy (eV)

5.55

Discovery & recognition

Discovery year / period (PubChem)

1945

Discovery credited to (RSC)

Jacob .A. Marinsky, Lawrence E. Glendenin, and Charles D. Coryell

Date or period recorded by RSC

1945

Discovery place

Oak Ridge, Tennessee, United States

An ancient date does not identify a first human discovery. Different references may date observation, isolation and formal recognition differently.

Natural occurrence & production

This radioactive element has no stable isotopes. It is principally obtained through nuclear reactions, although minute natural occurrences are known.

“Promethium’s longest-lived isotope has a half-life of only 18 years.”

Royal Society of Chemistry · occurrence excerpt ↗

Continue the research

Reference values are not product specifications. Blank values have not been estimated. For superheavy elements, some properties and family assignments are theoretical or incompletely measured.