Curium
Curium is a hard, silvery, intensely radioactive metal named after Marie and Pierre Curie. It has no industrial or commercial use, but a specific isotope has quietly ridden along on several NASA Mars missions, serving as the radiation source inside instruments that analyze Martian rock and soil.
- Group · Period
- — · 7
- At room temp
- solid
- Melts at
- 1618 K
- Density
- 13.51 g/cm³
- Discovered
- 1944
Uses
Curium has no commercial or industrial use — it’s produced in only small quantities and is far too radioactive and expensive for anything outside a laboratory. Its one genuinely practical application has been in space exploration: curium-244 has served as the alpha-particle source inside X-ray spectrometer instruments carried by several NASA Mars rovers, where its steady radioactive emissions are used to help determine the chemical composition of rocks and soil at a distance. Beyond that specialized role, curium exists mainly as a subject of nuclear and actinide chemistry research.
History
Curium was first produced in 1944 by Glenn Seaborg, Ralph James, and Albert Ghiorso at Berkeley, who bombarded plutonium with alpha particles under the same wartime secrecy that surrounded americium’s discovery that same year. Like americium, its existence was announced publicly for the first time on a children’s radio program in 1945, only after the classified work behind it could be disclosed. It was named in honor of Marie and Pierre Curie, continuing the periodic table’s tradition of naming elements after pioneering scientists.
Fun facts
- Curium is named after Marie and Pierre Curie, one of very few elements honoring two people at once.
- Curium-244 has served as the alpha-particle source inside instruments on several NASA Mars rovers, used to analyze the chemistry of Martian rock and soil.
- Curium is radioactive enough that some of its compounds visibly glow due to the intense energy they release, without any external light source.
Frequently asked questions
Does curium have any practical use?
Its only real application is scientific: curium-244 has been used as the alpha-particle source in spectrometer instruments aboard several Mars rovers, helping determine the elemental composition of rocks and soil. Outside of that kind of specialized instrumentation, curium has no commercial or industrial role.
Why does curium glow?
Some curium compounds are radioactive enough that the energy they constantly release excites the surrounding material, producing a visible glow without any external light source — a phenomenon called self-luminescence, seen in a few other highly radioactive substances as well.
Who is curium named after?
Marie and Pierre Curie, the physicists whose pioneering work on radioactivity gave the field much of its early foundation. Honoring both of them with one element name reflects how closely linked their research was.
Compounds
2 notable compounds containing Cm
- CmO2oxide
Curium dioxide
A black, fluorite-structured oxide representing curium's less common +4 oxidation state, prepared by igniting curium compounds in oxygen. It converts to the more stable sesquioxide on further heating.
- Cm2O3oxide
Curium sesquioxide
A tan-to-white solid holding curium in its dominant +3 oxidation state, the more thermodynamically stable of curium's two well-characterized oxides. It has been made and studied only in milligram quantities because of curium's intense radioactivity.
Isotopes
19 known isotopes
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| Isotope | Natural abundance | Half-life | Decay mode | Mass excess | Binding energy / nucleon | Decay width |
|---|---|---|---|---|---|---|
| Cm-245 | — | 8423 Y | Alpha decay (100%), Spontaneous fission (6.1e-7%) | 61,004.52 keV | 7,515.77 keV | 1.72 × 10-27 eV |
| Cm-247 | — | 1.56E+7 Y | Alpha decay (100%) | 65,533.11 keV | 7,501.93 keV | 9.27 × 10-31 eV |
| Cm-248 | — | 3.48E+5 Y | Alpha decay (91.61%), Spontaneous fission (8.39%) | 67,392.75 keV | 7,496.73 keV | 4.15 × 10-29 eV |
Show all 19 isotopes
| Cm-233 | — | 23 s | Electron capture / beta-plus decay (80%), Alpha decay (20%) | 47,293.34 keV | 7,546 keV | 1.98 × 10-17 eV |
| Cm-234 | — | 51 s | Alpha decay (40%), Spontaneous fission (40%), Electron capture / beta-plus decay (20%) | 46,722.41 keV | 7,550.69 keV | 8.95 × 10-18 eV |
| Cm-235 | — | — | Alpha decay (1.1%) | 48,013 keV | 7,547 keV | — |
| Cm-236 | — | 6.8 m | Electron capture (82%), Alpha decay (18%) | 47,852.82 keV | 7,550.31 keV | 1.12 × 10-18 eV |
| Cm-237 | — | — | Alpha decay (1%) | 49,247.15 keV | 7,546.62 keV | — |
| Cm-238 | — | 2.2 h | Electron capture (96.16%), Alpha decay (3.84%), Spontaneous fission (0.048%) | 49,445.2 keV | 7,548 keV | 5.76 × 10-20 eV |
| Cm-239 | — | 2.7 h | Electron capture (100%), Alpha decay (0.001%) | 51,146.96 keV | 7,543.07 keV | 4.69 × 10-20 eV |
| Cm-240 | — | 27 d | Alpha decay (99.5%), Electron capture (0.5%), Spontaneous fission (0.0000039%) | 51,724.22 keV | 7,542.86 keV | 1.96 × 10-22 eV |
| Cm-241 | — | 32.8 d | Electron capture (99%), Alpha decay (1%) | 53,701.77 keV | 7,536.85 keV | 1.61 × 10-22 eV |
| Cm-242 | — | 162.88 d | Alpha decay (100%), Spontaneous fission (0.0000062%), 34SI (1e-14%) | 54,803.7 keV | 7,534.5 keV | 3.24 × 10-23 eV |
| Cm-243 | — | 29.1 Y | Alpha decay (99.71%), Electron capture (0.29%), Spontaneous fission (5.3e-9%) | 57,181.94 keV | 7,526.93 keV | 4.97 × 10-25 eV |
| Cm-244 | — | 18.11 Y | Alpha decay (100%), Spontaneous fission (0.000137%) | 58,451.84 keV | 7,523.95 keV | 7.98 × 10-25 eV |
| Cm-246 | — | 4706 Y | Alpha decay (99.97385%), Spontaneous fission (0.02615%) | 62,616.91 keV | 7,511.47 keV | 3.07 × 10-27 eV |
| Cm-249 | — | 64.15 m | Beta-minus decay (100%) | 70,750.7 keV | 7,485.55 keV | 1.19 × 10-19 eV |
| Cm-250 | — | 8.3E+3 Y | Spontaneous fission (74%), Alpha decay (18%), Beta-minus decay (8%) | 72,989.59 keV | 7,478.94 keV | 1.74 × 10-27 eV |
| Cm-251 | — | 16.8 m | Beta-minus decay (100%) | 76,647.98 keV | 7,466.72 keV | 4.53 × 10-19 eV |