Curium
Element 96 · Actinide
Curium is a hard, brittle, silvery metal that is so radioactive it glows with a purple light in the dark and generates significant heat. It was the third transuranium element discovered and is named for Marie and Pierre Curie. Curium-244 has been used as a heat source in radioisotope generators and as an alpha-particle source in scientific instruments, including on the Mars rovers' spectrometers.
Key facts
| Atomic number | 96 |
|---|---|
| Atomic weight | [247] |
| Category | Actinide |
| Group / Period | — / 7 |
| Block | f |
| Electron configuration | [Rn] 5f7 6d1 7s2 |
| Common oxidation states | +3, +4 |
| State at STP | Solid |
| Electronegativity | 1.28 |
| Density | 13.51 g/cm3 |
| Melting point | 1340 °C |
| Boiling point | 3110 °C |
Occurrence
Curium is entirely synthetic, made by bombarding plutonium-239 with alpha particles or by neutron irradiation in reactors. It has no natural occurrence.
Applications
Curium-244 heat sources for remote power systems
Alpha-particle sources for X-ray spectrometers on space probes
Target material for synthesizing heavier elements
Common compounds
- Curium(III) oxide (Cm2O3)
- Curium(IV) oxide (CmO2)
- Curium(III) fluoride (CmF3)
Curium was discovered in 1944 by Glenn Seaborg's team but its discovery was kept secret until 1945; Seaborg announced it on a children's radio quiz show.
Data source: IUPAC standard atomic weights 2021