Chemical element · Atomic number 61
Promethium
Promethium in the periodic table: atomic number 61, electron configuration, atomic mass, physical data, oxidation states, media credit and visible sources.
Lanthanide
solid
[144.91276] u
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Atomic classification
Shell occupancy
Promethium in the Bohr shell model
This shows the electron distribution of the neutral atom in a simplified shell model.
- K · n=1
- 2 electrons
- L · n=2
- 8 electrons
- M · n=3
- 18 electrons
- N · n=4
- 23 electrons
- O · n=5
- 8 electrons
- P · n=6
- 2 electrons
- Electron configuration
- [Xe]6s2 4f5
- Electrons per shell
- 2 · 8 · 18 · 23 · 8 · 2
- Group
- not reported
- Period
- 6
- Block
- F
- Element category
- Lanthanide
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Physical and chemical properties
- Atomic mass
- [144.91276] u
- Standard state
- solid
- Density
- 7.26 g/cm³
- Melting point
- 1,315 K
- Boiling point
- 3,273 K
- Electronegativity
- not reported
- First ionisation energy
- 5.55 eV
- Oxidation states
- +3
- Discovery
- 1945
Safety and periodic classification
Safety
Safe handling cannot be inferred from Promethium's position in the periodic table alone. Laboratory, classroom and disposal decisions must follow the documentation for the exact material and its safety data sheet.
Position and comparison
Promethium is in period 6 and the F block. Its direct neighbours by atomic number are Neodymium and Samarium. The snapshot does not report a Pauling electronegativity. Periodic trends are compared only through the separately sourced neighbouring values.
Sources and scope
PubChem attributes element data to sources including IUPAC, NIST and IAEA. Quanta stores the referenced snapshot locally and leaves unknown values unavailable.