Curium (Cm)
Actinide · f-block · period 7
Hard, brittle, silvery radioactive metal that glows purple-pink in the dark.
Curium (symbol Cm) is chemical element number 96, a actinide in the actinide series (f-block), period 7 of the periodic table. Its standard atomic weight is (247) and its electron configuration is [Rn] 5f7 6d1 7s2. At room temperature it is a solid, and it is radioactive. Named after Marie and Pierre Curie.
Properties
| Atomic number | 96 |
|---|---|
| Atomic mass | (247) |
| Category | Actinide |
| Block | f-block |
| Group · Period | f-block series · 7 |
| Electron configuration | [Rn] 5f7 6d1 7s2 |
| Electrons per shell | 2, 8, 18, 32, 25, 9, 2 |
| State at 25 °C | solid |
| Melting point | 1613 K |
| Boiling point | 3383 K |
| Density | 13.51 g/cm³ |
| Electronegativity (Pauling) | 1.28 |
| Radioactive | Yes — no stable isotope |
| Origin | synthetic |
| Discovered | 1944 · Seaborg, James & Ghiorso |
Key facts about Curium
- Named after Marie and Pierre Curie.
- So radioactive it glows with a soft purple light in the dark.
- NASA's Mars rovers carry curium to analyse rocks by bouncing its radiation off them (APXS instrument).
- Generates so much heat it could be a compact power source.
What Curium is used for
Alpha-particle X-ray spectrometers on Mars rovers, research into heavier elements, potential compact power sources.
Where it sits in the periodic table
Curium is in the actinide series, period 7, of the f-block. Its electron configuration [Rn] 5f7 6d1 7s2 means its outermost shell holds 2 electrons, which is what places it here and explains much of its chemistry. See Curium on the interactive table →
Curium — frequently asked questions
What is Curium used for?
Alpha-particle X-ray spectrometers on Mars rovers, research into heavier elements, potential compact power sources.
Is Curium radioactive?
Yes. Curium has no stable isotope, so every form of it is radioactive.
What is the electron configuration of Curium?
Curium has the electron configuration [Rn] 5f7 6d1 7s2, which is 2, 8, 18, 32, 25, 9, 2 electrons per shell.
What group and period is Curium in?
Curium is in the actinide series (f-block), period 7, in the f-block. Its outer shell holds 2 electrons.
Who discovered Curium?
Curium was discovered in 1944 by Seaborg, James & Ghiorso.