Promethium

Document v1 · published by Koskamo · updated 2026-10-04

Promethium (Pm) is chemical element 61, a lanthanide in the f-block, period 6 (PubChem).

Atomic number: 61
Symbol: Pm
Group: none (f-block)
Period: 6
Atomic mass: 144.91276 u
Electron configuration: [Xe]6s2 4f5
Atomic radius (van der Waals): 236 pm
Ionization energy: 5.55 eV
Oxidation states: +3
Standard state: Solid
Melting point: 1315 K
Boiling point: 3273 K
Density: 7.26 g/cm³
Chemical group: Lanthanide
Year discovered: 1945

Source and provenance

Original source: pubchem.ncbi.nlm.nih.gov
Published on Koskamo by: Koskamo
Citation version: Document v1
Reuse: PubChem periodic table data (NIH/NLM, pubchem.ncbi.nlm.nih.gov/ptable); group and period from Jefferson Lab via PubChem

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Version history

Published by Koskamo2026-10-04
Version 1