Promethium

Metal

Symbol: Pm
Atomic number: 61
Atomic mass: (144.9127)
Group: Lanthanide
CAS-number: 7440-12-2

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Np

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Electronic data

Shells: 2, 8, 18, 23, 8, 2
Orbitals: [Xe] 4f⁵ 6s²
Electronegativity: --, 1.1
1. Ionization potential: 5.55 eV
2. Ionization potential: 10.903 eV
3. Ionization potential: 22.283 eV
Oxidation states: 3
Electrical conductivity: --

Thermal data

Melting point: 1042 °C
Boiling point: 3000 °C (estimated)
Specific heat: 0.18 J/gK
Heat of fusion: -- kJ/mol
Heat of vaporization: -- kJ/mol
Thermal conductivity: 0.179 W/cmK

Steric data

Atomic radius: 2.62 Å
Ionic radius: 1.09 Å (+3)
Covalent radius: 1.63 Å
Atomic volume: 22.39 cm³/mol
Density (293 K): 6.475 g/cm³
Crystal structure: hexagonal

Nuclide	Mass	Spin	Halflife	Decay mode	Decay tree
¹⁴³Pm	142.911	5/2	265y	EC	View
¹⁴⁴Pm	144	5	360y	EC	View
¹⁴⁵Pm	144.913	5/2	17.7y	EC, α	View
¹⁴⁶Pm	146	3	5.53y	EC, β-	View
¹⁴⁷Pm	146.915	7/2	2.62y	β-	View
¹⁴⁸Pm	148	1	5.37d	β-	View
¹⁴⁸Pmm	148	6	41.3d	β-, IT	View
¹⁴⁹Pm	149	7/2	2.212d	β-	View
¹⁵¹Pm	151	5/2	1.183d	β-	View

Name origin:	Named for the Greek god, Prometheus.
Description:	Rare earth metal of synthetic origin on the earth, naturally made in stars.
Discovered by:	J.A. Marinsky, L.E. Glendenin, C.D. Coryell
Year:	1945
Place:	United States
Sources:	Does not occur naturally. Found among fission products of uranium, thorium, and plutonium.
Use(s):	It has been used as a source of radioactivity for thickness-measuring gauges.

Promethium

Physical data

Electronic data

Thermal data

Steric data

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