Elements / 61
61Pm[145]
Promethium
Lanthanide · f-block · ring P
Promethium is element 61, a lanthanide. It is one of the lanthanides, which the spiral keeps in line on ring P instead of exiling them to a strip below the table.
Properties
| Density | 7.26 g/cm³ | Terrain → |
|---|---|---|
| Melting point | 1,315 K · 1,042 °C | Terrain → |
| Boiling point | 3,273 K · 3,000 °C | Terrain → |
| Electronegativity | 1.13 | Terrain → |
| First ionization energy | 540 kJ/mol | Terrain → |
| Atomic weight | 145 u | Terrain → |
| Crustal abundance | 2.0 × 10⁻²³ ppm | Terrain → |
| Discovered | 1945 | Terrain → |
Values from open reference data; see sources. "Terrain" opens that property as a 3D landscape across the whole spiral.
Two things you might not know
- Branner predicted it in 1902; it was first chemically identified in 1945 by Marinsky, Glendenin and Coryell.
- Named for the Greek figure who stole fire from heaven; no known isotope of it has a half-life longer than 17.7 years.
Checked against periodic.lanl.gov.
Lanthanides
- La Lanthanum
- Ce Cerium
- Pr Praseodymium
- Nd Neodymium
- Pm Promethium
- Sm Samarium
- Eu Europium
- Gd Gadolinium
- Tb Terbium
- Dy Dysprosium
- Ho Holmium
- Er Erbium
- Tm Thulium
- Yb Ytterbium
Ring P (period 6)
Play with Promethium
Watch it fly into its seat, or raise the whole spiral into a landscape and see where it peaks.