NO. 061Lanthanide

Pm

Promethium

Promethium is a radioactive lanthanide with no stable isotopes, mainly used in research and nuclear batteries.

Crystal Structure

Double hexagonal close-packed (dhcp)

Atomic Mass145 u

Density7.26 g/cm³

Melting Point1315 K

Boiling Point3273 K

Atomic Radius183 pm

Electronegativity1.13

Ionization Energy540 kJ/mol

Electron Affinity50 kJ/mol

Bonding TypeMetallic

Oxidation States3

Acid/BaseBasic

ReactivityHigh

Electron Configuration

[Xe] 4f5 6s2

Discovered ByJacob A. Marinsky

Year1945

Known Isotopes

Pm-145Pm-147