Element Promethium
All of its isotopes are radioactive; it is extremely rare, with only about 500–600 grams naturally occurring in Earth’s crust at any given time.
Promethium is a chemical element with the symbol Pm and atomic number 61.
Promethium is one of only two radioactive elements that are followed in the periodic table by elements with stable forms, the other being technetium. Chemically, promethium is a lanthanide. Promethium shows only one stable oxidation state of +3.
The element’s atomic radius is the second largest among all the lanthanides but is only slightly greater than those of the neighboring elements
Promethium belongs to the cerium group of lanthanides and is chemically very similar to the neighboring elements
Names and Identifiers
| Chemical Formula: | Pm |
| CAS: | 7440-12-2 |
| Molecular Weight: | 145.00000g/mol |
| EC Number : | n/a |
| MDL Number: | n/a |
| Color: | silvery-white/ metallic |
| Other Names: | Prometio, Promécio |
| PubChem CID: | 23944 |
| IUPAC Name: | Promethium |
| Inchl: | InChI=1S/Pm |
| InChI Key: | VQMWBBYLQSCNPO-UHFFFAOYSA-N |
| Canonical SMILES: | [Pm] |
| ICSC Number: | n/a |
Physical & Chemical Properties
| Phase: | Solid |
| Density: | 7.26 g/cm³ |
| Boiling Point: | 3273 K (3000 °C, 5432 °F) |
| Melting Point: | 1315 K (1042 °C, 1908 °F) |
| Molecular Formula: | Pm |
| Flash Point: | n/a |
| Exact Mass: | 144.91300 |
Promethium is the only lanthanide and one of only two elements among the first 83 that has no stable or long-lived (primordial) isotopes.
Radiosotope data
| Isotope | Mass/Da | Half-life | Mode of decay | Nuclear spin | Nuclear magnetic moment |
|---|---|---|---|---|---|
| 143Pm | 142.910928 | 265 d | EC to 143Nd | 5/2 | 3.8 |
| 144Pm | 143.912586 | 360 d | EC to 144Nd | 5 | 1.7 |
| 145Pm | 144.912743 (4) | 17.7 y | EC to 145Nd; α to 141Pr | 5/2 | |
| 146Pm | 145.914693 | 5.53 y | EC to 146Nd; β– to 146Sm | 3 | |
| 147Pm | 146.915134 | 2.6234 y | β– to 147Sm | 7/2 | 2.6 |
| 148Pm | 147.91747 | 5.37 d | β– to 148Sm | 1 | 2.0 |
| 149Pm | 148.918330 | 2.212 d | β– to 149Sm | 7/2 | 3.3 |
| 150Pm | 149.92098 | 2.68 h | β– to 150Sm | 1 | |
| 151Pm | 150.92120 | 1.183 d | β– to 151Sm | 5/2 | 1.8 |