Curium (kewr-ee-əm) is a synthetic chemical element with the symbol "Cm" and atomic number 96. This radioactive transuranic element of the actinide series was named after Marie Skłodowska-Curie and her husband Pierre Curie. Curium was first intentionally produced and identified in summer 1944 by the group of Glenn T. Seaborg at the University of California, Berkeley. The discovery was kept secret and only released to the public in November 1945. Most curium is produced by bombarding uranium or plutonium with neutrons in nuclear reactors – one tonne of spent nuclear fuel contains about 20 grams of curium. Curium is a hard, dense silvery metal with a relatively high melting point and boiling point for an actinide. Whereas it is paramagnetic at ambient conditions, it becomes antiferromagnetic upon cooling, and other magnetic transitions are also observed for many curium compounds. In compounds, curium usually exhibits valence +3 and sometimes +4, and the +3 valence is predominant in solutions. Curium readily oxidizes, and its oxides are a dominant form of this element. It forms strongly fluorescent complexes with various organic compounds, but there is no evidence of its incorporation into bacteria and archaea. When introduced into human body, curium accumulates in the bones, lungs and liver where it promotes cancer. All known isotopes of curium are radioactive and have a small critical mass for a sustained nuclear chain reaction. They predominantly emit α-particles, and the heat released in this process can potentially produce electricity in radioisotope thermoelectric generators. This application is hindered by the scarcity, high cost and radioactivity of curium isotopes. Curium is used in production of heavier actinides and of the 238Pu radionuclide for power sources in artificial pacemakers. It served as the α-source in the alpha particle X-ray spectrometers installed on the Sojourner, Mars, Mars 96, Athena, Spirit and Opportunity rovers to analyze the composition and structure of the rocks on the surface of Mars and the Moon. In compounds, curium usually exhibits valence +3 and sometimes +4, and the +3 valence is predominant in solutions. Curium readily oxidizes, and its oxides are a dominant form of this element. It forms strongly fluorescent complexes with various organic compounds, but there is no evidence of its incorporation into bacteria and archaea. When introduced into human body, curium accumulates in the bones, lungs and liver where it promotes cancer. All known isotopes of curium are radioactive and have a small critical mass for a sustained nuclear chain reaction. They predominantly emit α-particles, and the heat released in this process can potentially produce electricity in radioisotope thermoelectric generators. This application is hindered by the scarcity, high cost and radioactivity of curium isotopes. curium had likely been produced in previous nuclear experiments, it was first intentionally synthesized, isolated and identified in 1944, at the University of California, Berkeley by Glenn T. Seaborg, Ralph A. James, and Albert Ghiorso. In their experiments, they used a 60-inch (150 cm) cyclotron. Curium was chemically identified at the Metallurgical Laboratory (now Argonne National Laboratory) at the University of Chicago. It was the third transuranium element to be discovered even though it is the fourth in the series – the lighter element americium was unknown at the time. The new element was named after Marie Skłodowska-Curie and her husband Pierre Curie who are noted for discovering radium and for their work in radioactivity. It followed the example of gadolinium, a lanthanide element above curium in the periodic table, which was named after the explorer of the rare earth elements Johan Gadolin. "As the name for the element of atomic number 96 we should like to propose "curium" , with symbol Cm. The evidence indicates that element 96 contains seven 5f electrons and is thus analogous to the element gadolinium with its seven 4f electrons in the regular rare earth series. On this base element 96 is named after the Curies in a manner analogous to the naming of gadolinium, in which the chemist Gadolin was honored." The first curium samples were barely visible, and were identified by their radioactivity. Louis Werner and Isadore Perlman created the first substantial sample of 30 µg curium-242 hydroxide at the University of California in 1947 by bombarding americium-241 with neutrons. References: ^ Schenkel, R (1977). "The electrical resistivity of 244Cm metal". Solid State Communications 23 (6): 389. doi:10.1016/0038-1098(77)90239-3. ^ Hall, Nina (2000). The New Chemistry: A Showcase for Modern Chemistry and Its Applications. Cambridge University Press. pp. 8–9. ISBN 9780521452243. ^ Seaborg, G. T.; James, R. A. and Ghiorso, A.: "The New Element Curium (Atomic Number 96)", NNES PPR (National Nuclear Energy Series, Plutonium Project Record), Vol. 14 B, The Transuranium Elements: Research Papers, Paper No. 22.2, McGraw-Hill Book Co., Inc., New York, 1949; Abstract; Full text (January 1948). ^ Morss, L. R.; Edelstein, N. M. and Fugere, J. (eds): The Chemistry of the Actinide Elements and transactinides, volume 3, Springer-Verlag, Dordrecht 2006, ISBN 1- 4020-3555-1. ^ Pepling, Rachel Sheremeta (2003). "Chemical & Engineering News: It's Elemental: The Periodic Table – Americium". Retrieved 07 -12-2008. ^ Krebs, Robert E. The history and use of our earth's chemical elements: a reference guide, Greenwood Publishing Group, 2006, ISBN 0313334382 p. 322 ^ Harper, Douglas. "pandemonium". Online Etymology Dictionary. ^ Harper, Douglas. "delirium". Online Etymology Dictionary. ^ Audi, G (1997). "The N? evaluation of nuclear and decay properties". Nuclear Physics A 624 (1): 1. Bibcode 1997NuPhA.624....1A. doi:10.1016/S0375-9474 (97)00482-X. ^ Seaborg, G. T. U.S. Patent 3,161,462 "Element", Filing date: 7 February 1949, Issue date: December 1964 ^ Sasahara, Akihiro; Matsumura, Tetsuo; Nicolaou, Giorgos; Papaioannou, Dimitri (2004). "Neutron and Gamma Ray Source Evaluation of LWR High Burn-up UO2 and MOX Spent Fuels". Journal of Nuclear Science and Technology 41 (4): 448–456. doi:10.3327/jnst.41.448. ^ Institut de Radioprotection et de Sûreté Nucléaire: "Evaluation of nuclear criticality safety. data and limits for actinides in transport", p. 16 ^ National Research Council (U.S.). Committee on Separations Technology and Transmutation Systems (1996). Nuclear wastes: technologies for separations and transmutation. National Academies Press. pp. 231–. ISBN 9780309052269. Retrieved 19 April 2011.