Periodic TableCurium (Cm)
Curium is an actinide with atomic number 96, in period 7, in the f-block of the periodic table. Its atomic mass is 247 u and its electron configuration is [Rn] 5f⁷ 6d¹ 7s². Solid at 25 °C.
Key facts
| Atomic number | 96 |
|---|---|
| Atomic mass | 247 u |
| Category | Actinide |
| Period | 7 |
| Group | f-block, no group number |
| Block | f |
| Electron configuration | [Rn] 5f⁷ 6d¹ 7s² |
| Electrons per shell | 2, 8, 18, 32, 25, 9, 2 |
| Electronegativity (Pauling) | 1.3 |
| Oxidation states | +3, +4, +5, +6common in bold |
| State at 25 °C | Solid |
| Melting point | 1618 K1344.85 °C |
| Boiling point | 3400 K3126.85 °C |
| Density | 13.51 g/cm³ |
Atomic properties
| First ionization energy | 5.991 eV |
|---|---|
| Electron affinity | --- |
| Atomic radius | 174 pm |
| Covalent radius | 169 pm |
| Van der Waals radius | 245 pm |
| Common ions | Cm³⁺ |
| Protons, neutrons, electrons | 96, 151, 96 |
Physical and thermal properties
| Molar volume | 18.05 cm³/mol |
|---|---|
| Heat of fusion | 13.85 kJ/mol |
| Heat of vaporization | --- |
| Specific heat | --- |
| Thermal conductivity | --- |
| Thermal expansion | --- |
| Mohs hardness | --- |
| Young’s modulus | --- |
| Crystal structure | Simple hexagonal |
| Magnetic type | Paramagnetic |
Identification and history
| CAS number | 7440-51-9 |
|---|---|
| Latin name | Curium |
| Discovered by | G. Seaborg, R. James, L. Morgan, A. Ghiorso · 1944 |
| Named by | --- |
Natural isotopes
Curium has no stable isotopes: every isotope is radioactive.
Data checked against PubChem (NIH), IUPAC, the NIST Atomic Spectra Database and the IAEA (NUBASE and AME), the same data you see in the app.
A dash (---) means there is no reliable published measurement. The app never makes one up.
See Curium in the app
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