96[247]CmCurium
Curium (Cm) — element 96actinide · period 7
Curium is a chemical element with the symbol Cm and atomic number 96. It is an actinide in period 7 of the periodic table (the f-block), with a standard atomic mass of [247] u. At room temperature (25 °C) curium is a solid.
💡 Known for: Named after Marie and Pierre Curie; curium-244 powers X-ray spectrometers on Mars rovers.
# Curium properties
| Symbol | Cm |
|---|---|
| Atomic number | 96 |
| Atomic mass | [247] u |
| Category | actinide |
| Group | — (f-block, no group number) |
| Period | 7 |
| Block | f-block |
| Electron configuration | [Rn] 5f⁷ 6d¹ 7s² |
| Full configuration | 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 4f¹⁴ 5s² 5p⁶ 5d¹⁰ 5f⁷ 6s² 6p⁶ 6d¹ 7s² |
| Electrons per shell | 2, 8, 18, 32, 25, 9, 2 |
| Protons / electrons | 96 / 96 |
| State at 25 °C | solid |
| Melting point | 1613 K (1339.8 °C, 2443.7 °F) |
| Boiling point | 3383 K (3109.8 °C, 5629.7 °F) |
| Density | 13.51 g/cm³ |
| Electronegativity (Pauling) | 1.28 |
| First ionization energy | 5.991 eV |
| Atomic radius | 169 pm |
| Discovered | 1944 |
# Electron configuration of curium
The electron configuration of curium is [Rn] 5f⁷ 6d¹ 7s², written out in full as 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 4f¹⁴ 5s² 5p⁶ 5d¹⁰ 5f⁷ 6s² 6p⁶ 6d¹ 7s². Its 96 electrons fill 7 shells as 2, 8, 18, 32, 25, 9, 2, so the outermost shell holds 2 electrons.
# Related elements
AmAmericiumprevious elementBkBerkeliumnext elementAcActiniumactinideThThoriumactinidePaProtactiniumactinideUUraniumactinideNpNeptuniumactinidePuPlutoniumactinideCfCaliforniumactinideEsEinsteiniumactinide
# Curium FAQ
What is the atomic number of curium?
The atomic number of curium is 96: every curium atom has 96 protons in its nucleus. Its symbol is Cm.
What is the atomic mass of curium?
The standard atomic mass of curium is [247] u (the mass number of its longest-lived isotope, since it has no stable isotopes).
What is the electron configuration of curium?
Curium's electron configuration is [Rn] 5f⁷ 6d¹ 7s² (1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 4f¹⁴ 5s² 5p⁶ 5d¹⁰ 5f⁷ 6s² 6p⁶ 6d¹ 7s²), with 2, 8, 18, 32, 25, 9, 2 electrons per shell.
Is curium a metal?
Yes. Curium is an actinide, one of the metals.
What is the melting point of curium?
Curium melts at 1613 K (1339.8 °C, 2443.7 °F) and boils at 3383 K (3109.8 °C, 5629.7 °F).
What is curium used for / known for?
Named after Marie and Pierre Curie; curium-244 powers X-ray spectrometers on Mars rovers.