Symbol
Pm
Atomic Number
61
Atomic Mass
145
Protons
61
Neutrons
84
Electrons
61
Type
Lanthanide
Isotopes
Promethium-145, Promethium-147
Discovery Year
1945
Discovered By
Charles D. Coryell, Walter G. B. C. Seaborg
Group
3
Period
6
Boiling Point
3000°C
Melting Point
1100°C
Electron Configuration
[Xe] 6s² 4f⁵
Density (g/cm³)
7.26
Crystal Structure
Hexagonal
Magnetism
Paramagnetic
Abundance in Earth's Crust
Trace
Phase at Room Temperature
Solid