Promethium

Lanthanide · atomic number 61

61145PmPromethiumSolidLanthanide

Promethium, originally prometheum, is a chemical element with the symbol Pm and atomic number 61. All of its isotopes are radioactive; it is one of only two such elements that are followed in the periodic table by elements with stable forms, a distinction shared with technetium. Chemically, promethium is a lanthanide, which forms salts when combined with other elements.

Properties of Promethium

Element category	Lanthanide
Atomic number	61
Atomic mass	145 u
Phase at STP	Solid
Group	3
Period	6
Block	f
Electron configuration	[Xe] 4f5 6s2
Electrons per shell	2, 8, 18, 23, 8, 2
Electronegativity (Pauling)	1.13
Melting point	1315 K (1042 °C)
Boiling point	3273 K (3000 °C)
Density	7.26 g/cm3
Discovered by	Chien Shiung Wu
Named by	Isotopes of promethium

← Neodymium · Periodic table · Samarium → Sm

About the lanthanide group

The rare-earth “inner transition” metals that give strong permanent magnets, screen phosphors and catalyst polish.

Data: Periodic-Table-JSON (CC BY-SA 3.0) · stored statically on our server. https://en.wikipedia.org/wiki/Promethium

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