61Solid
Pm 145 Atomic mass · uLanthanides
Promethium
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.
Discovery 1947 (Chien Shiung Wu)
K2L8M18N23O8P2
Physical properties
Values for the element in its standard state.
- Density
- 7.264g/cm³
- Melting point
- 1,373K
- Boiling point
- 3,273K
- Atomic radius
- Not available
- Bonding type
- Metallic
- Molar heat
- Not available
Inside the atom
Electron arrangement and the energy behind its behavior.
Full electron configuration
1s, 2 electrons; 2s, 2 electrons; 2p, 6 electrons; 3s, 2 electrons; 3p, 6 electrons; 3d, 10 electrons; 4s, 2 electrons; 4p, 6 electrons; 4d, 10 electrons; 5s, 2 electrons; 5p, 6 electrons; 4f, 5 electrons; 6s, 2 electrons;
[Xe] represents 54 core electrons. The full view shows them explicitly.
61 electrons Orbital order preserved from source
- Electronegativity
- 1.13Pauling scale
- First ionization energy
- 540kJ/mol
- Electron affinity
- 50kJ/mol
- Van der Waals radius
- Not available
Pm PromethiumAtomic number 61
540kJ/mol
Atomic numberGaps indicate unavailable data
About promethium
- Appearance
- Metallic
- Discovery
- 1947 (Chien Shiung Wu)
- Data source
- Read the reference
A missing value means it is unavailable in this reference dataset. Values can vary with measurement method and conditions.