- Curium (Cm) is a hard, silvery, radioactive metal with atomic number 96, belonging to the actinide series.
- Its electron configuration is [Rn] 5f⁷ 6d¹ 7s², and it exhibits oxidation states from +3 to +6, with +3 being by far the most stable and common in compounds. The atomic structure contains ninety-six protons, typically one hundred and fifty-one neutrons in curium-247 (²⁴⁷Cm) or one hundred and fifty-four neutrons in curium-250 (²⁵⁰Cm), and ninety-six electrons arranged in seven shells.
- Curium does not occur naturally and is produced artificially in nuclear reactors by bombarding plutonium or americium with neutrons. The most notable isotopes are curium-242 (²⁴²Cm), with a half-life of 162.8 days, which produces intense heat through alpha decay, and curium-244 (²⁴⁴Cm), with a half-life of 18.1 years, which emits both alpha particles and significant gamma radiation.
- Curium was discovered in 1944 by Glenn T. Seaborg, Ralph James, and Albert Ghiorso at the University of California, Berkeley, during work on the Manhattan Project. It was synthesized by bombarding plutonium-239 (²³⁹Pu) with alpha particles in a cyclotron, producing curium-242 and a neutron. The discovery was kept classified until after World War II, and the element was named after Marie Curie and Pierre Curie, pioneers in the study of radioactivity.
- Curium’s applications are limited due to its extreme radioactivity and scarcity, but its intense heat production makes curium-244 and curium-242 valuable as heat sources in radioisotope thermoelectric generators (RTGs) for spacecraft and remote scientific equipment. Curium isotopes are also used in alpha particle sources for research and as targets for producing heavier transuranium and transactinide elements such as berkelium and californium.
- Chemically, curium behaves like other trivalent actinides and rare earth metals. In air, metallic curium slowly tarnishes, forming an oxide layer. Its most common compound is curium(III) oxide (Cm₂O₃), a stable, pinkish solid. Curium forms halides such as CmF₃, CmCl₃, and CmBr₃, as well as coordination complexes in aqueous solution. Higher oxidation states (+4, +5, +6) are rare and require strong oxidizing conditions.
- Biologically, curium has no natural role in living organisms and is highly toxic due to its alpha radiation. Inhaled curium tends to accumulate in bones and liver, where it remains for decades, increasing cancer risk. The high-energy radiation from certain isotopes also makes even small amounts of curium extremely hazardous to handle without heavy shielding.
- Environmentally, curium is present in trace amounts in spent nuclear fuel and high-level nuclear waste. Because of its radioactivity and long-lived isotopes, it is a contributor to the long-term radiotoxicity of nuclear waste, requiring secure and permanent storage solutions.
