Promethium (Pm)
Promethium
Promethium (Pm) is a lanthanide in period 6. Its relative atomic mass is [145] and the molar mass of the atom is [145] g/mol.
Atomic number 61
Atomic mass [145] predicted
Molar mass [145] g/mol
Category Lanthanide Solid
Properties of promethium
| Atomic number | 61 |
|---|---|
| Symbol | Pm |
| Latin name | Promethium |
| Relative atomic mass | [145] |
| Molar mass | [145] g/mol |
| Group, period, block | —, 6, f |
| Category | Lanthanide |
| State at 20 °C | Solid |
| Electron configuration | [Xe] 4f⁵ 6s² |
| Atomic radius | 185 pm |
Electron configuration of promethium
Electrons per shell
K2L8M18N23O8P2
Full notation
1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 4f⁵ 5s² 5p⁶ 6s²
Noble-gas notation
61 protons · 61 electrons[Xe] 4f⁵ 6s²
Formula and compounds of promethium
Simple substancePmpromethiumMolar mass of Pm: [145] g/mol
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Frequently asked questions
The relative atomic mass of promethium is [145], so the molar mass of the atom is [145] g/mol.
Full: 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 4f⁵ 5s² 5p⁶ 6s². Noble-gas notation: [Xe] 4f⁵ 6s².