96
Cm
Curium
247
Curium (Cm)
ActinidePeriod 7f-block-blockRadioactive
Curium is a transuranic radioactive chemical element with symbol Cm and atomic number 96. This element of the actinide series was named after Marie and Pierre Curie – both were known for their research on radioactivity. Curium was first intentionally produced and identified in July 1944 by the group of Glenn T. Seaborg at the University of California, Berkeley.
Latin name: Curium
Atomic Number
96
Atomic Mass
247 g/mol
Phase (STP)
Solid
Electron Config.
[Rn] 5f⁷ 6d¹ 7s²
General
SymbolCm
Atomic Number96
Atomic Mass247 g/mol
CategoryActinide
Period7
Blockf-block
Electron Configuration[Rn] 5f⁷ 6d¹ 7s²
Valence Electrons9
Coloursilvery metallic
Appearancesilvery metallic, glows purple in the dark
CAS NumberCAS7440-54-2
Physical Properties
Phase (STP)Solid
Density13.51 g/cm³
Melting Point1344.85°C · 2452.73°F · 1618.00 K
Boiling Point3109.85°C · 5629.73°F · 3383.00 K
Atomic Properties
Atomic Radius245 pm
Electronegativity1.28 Pauling
Ionization Energy581 kJ/mol
Oxidation States+3, +4
Ion ChargeCm3+/Cm4+
Crystal Structure
Crystal Structurehexagonal close-packed
Nuclear & Hazards
RadioactiveYes
Half-life1.56×10^7 years (Cm-247)
Abundance
In Earth's Crust0.0000000000001%
Discovery & History
Discovery Year1944
Discovered ByGlenn T. Seaborg, Ralph A. James, and Albert Ghiorso
Country of DiscoveryUSA
Isotopes of Curium
| Isotope | Abundance | Half-life | Decay |
|---|---|---|---|
| Cm-243 | — | 29.1 years | α, EC |
| Cm-244 | — | 18.1 years | α |
| Cm-245 | — | 8500 years | α |
| Cm-247 | — | 1.56 × 10⁷ years | α |
| Cm-248 | — | 3.4 × 10⁵ years | α, SF |