Science / Periodic Table of Elements / Curium (Cm): Atomic number: 96, Atomic mass: (247) g.mol -1, Electronegativity: unknown, Density: 13.51 g.cm-3 at 20°C, Melting point: 1340 °C, Boiling point: unknown, Vanderwaals radius: unknown, Ionic radius: unknown, Isotopes: 10, Electronic shell: [ Rn ] 5f7 6d1 7s2, Discovered by: G.T. Seaborg in 1944. Named after Pierre and Marie Curie. Curium is a hard, brittle, silvery metal that tarnishes slowly in dry air at room temperature. Curium does not occur naturally; it is typically produced artificially in nuclear reactors through successive neutron captures by plutonium and americium isotopes. Curium is very radioactive, more electropositive than Aluminum, chenically reactive. A few compounds of curium are known, as the fluorides. Although curium follows americium in the periodic system, it was actually known before americium and was the third transuranium element to be discovered. It was identified by Glenn Seaborg, James, and Albert Ghiorso in 1944 at the wartime Metallurgical Laboratory in Chicago as a result of helium-ion bombardment of 239Pu in the Berkeley Radiation Laboratory's 60-inch cyclotron. Visible amounts (30Mg) of 242Cm, in the form of the hydroxide, were first isolated by Werner and Perlman of the University of California, Berkeley in 1947. In 1950, Crane, Wallmann, and Cunningham found that the magnetic susceptibility of microgram samples of CmF3 was of the same magnitude as that of GdF3. This provided direct experimental evidence for assigning an electronic configuration to Cm+3. In 1951, the same workers prepared curium in its elemental form for the first time. Applications: Curium-242 and curium-244 are used in the space program as a heat source for compact thermionic and thermoelectric power generation. Being a alfa-emitter, its radiation can be easily shielded againts. Curium in the environment: Curium probably does occur naturally on Earth, but in incredibly small amounts. Concentrated uranium deposits may produce some atoms of it, by the same processes which produce atoms of neptunium and plutonium.
Science / Periodic Table of Elements / Curium (Cm): Atomic number: 96, Atomic mass: (247) g.mol -1, Electronegativity: unknown, Density: 13.51 g.cm-3 at 20°C, Melting point: 1340 °C, Boiling point: unknown, Vanderwaals radius: unknown, Ionic radius: MORE