Curium

  • curium, 96cm
    curium.jpg
    curium
    pronunciationm/ (kewr-ee-əm)
    appearancesilvery metallic, glows purple in the dark
    mass number[247]
    curium in the periodic table
    hydrogen helium
    lithium beryllium boron carbon nitrogen oxygen fluorine neon
    sodium magnesium aluminium silicon phosphorus sulfur chlorine argon
    potassium calcium scandium titanium vanadium chromium manganese iron cobalt nickel copper zinc gallium germanium arsenic selenium bromine krypton
    rubidium strontium yttrium zirconium niobium molybdenum technetium ruthenium rhodium palladium silver cadmium indium tin antimony tellurium iodine xenon
    caesium barium lanthanum cerium praseodymium neodymium promethium samarium europium gadolinium terbium dysprosium holmium erbium thulium ytterbium lutetium hafnium tantalum tungsten rhenium osmium iridium platinum gold mercury (element) thallium lead bismuth polonium astatine radon
    francium radium actinium thorium protactinium uranium neptunium plutonium americium curium berkelium californium einsteinium fermium mendelevium nobelium lawrencium rutherfordium dubnium seaborgium bohrium hassium meitnerium darmstadtium roentgenium copernicium nihonium flerovium moscovium livermorium tennessine oganesson
    gd

    cm

    (upn)
    americiumcuriumberkelium
    atomic number (z)96
    groupgroup n/a
    periodperiod 7
    blockf-block
    element category  actinide
    electron configuration[rn] 5f7 6d1 7s2
    electrons per shell2, 8, 18, 32, 25, 9, 2
    physical properties
    phase at stpsolid
    melting point1613 k ​(1340 °c, ​2444 °f)
    boiling point3383 k ​(3110 °c, ​5630 °f)
    density (near r.t.)13.51 g/cm3
    heat of fusion13.85 kj/mol
    vapor pressure
    p (pa) 1 10 100 1 k 10 k 100 k
    at t (k) 1788 1982
    atomic properties
    oxidation states+2, +3, +4, +5,[1] +6[2] (an amphoteric oxide)
    electronegativitypauling scale: 1.3
    ionization energies
    • 1st: 581 kj/mol
    atomic radiusempirical: 174 pm
    covalent radius169±3 pm
    color lines in a spectral range
    spectral lines of curium
    other properties
    natural occurrencesynthetic
    crystal structuredouble hexagonal close-packed (dhcp)
    double hexagonal close packed crystal structure for curium
    electrical resistivity1.25 µΩ·m[3]
    magnetic orderingantiferromagnetic-paramagnetic transition at 52 k[3]
    cas number7440-51-9
    history
    namingnamed after marie skłodowska-curie and pierre curie
    discoveryglenn t. seaborg, ralph a. james, albert ghiorso (1944)
    main isotopes of curium
    iso­tope abun­dance half-life (t1/2) decay mode pro­duct
    242cm syn 160 d sf
    α 238pu
    243cm syn 29.1 y α 239pu
    ε 243am
    sf
    244cm syn 18.1 y sf
    α 240pu
    245cm syn 8500 y sf
    α 241pu
    246cm syn 4730 y α 242pu
    sf
    247cm syn 1.56×107 y α 243pu
    248cm syn 3.40×105 y α 244pu
    sf
    250cm syn 9000 y sf
    α 246pu
    β 250bk
    category category: curium
    | references

    curium is a transuranic radioactive chemical element with the 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. the discovery was kept secret and only released to the public in november 1947. 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 the 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 serve as a heat source in radioisotope thermoelectric generators, but this application is hindered by the scarcity and high cost 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 several space probes, including the sojourner, spirit, opportunity and curiosity mars rovers and the philae lander on comet 67p/churyumov–gerasimenko, to analyze the composition and structure of the surface.

  • history
  • characteristics
  • synthesis
  • compounds and reactions
  • applications
  • safety
  • references
  • bibliography
  • external links

Curium, 96Cm
Curium.jpg
Curium
Pronunciationm/ (KEWR-ee-əm)
Appearancesilvery metallic, glows purple in the dark
Mass number[247]
Curium in the periodic table
Hydrogen Helium
Lithium Beryllium Boron Carbon Nitrogen Oxygen Fluorine Neon
Sodium Magnesium Aluminium Silicon Phosphorus Sulfur Chlorine Argon
Potassium Calcium Scandium Titanium Vanadium Chromium Manganese Iron Cobalt Nickel Copper Zinc Gallium Germanium Arsenic Selenium Bromine Krypton
Rubidium Strontium Yttrium Zirconium Niobium Molybdenum Technetium Ruthenium Rhodium Palladium Silver Cadmium Indium Tin Antimony Tellurium Iodine Xenon
Caesium Barium Lanthanum Cerium Praseodymium Neodymium Promethium Samarium Europium Gadolinium Terbium Dysprosium Holmium Erbium Thulium Ytterbium Lutetium Hafnium Tantalum Tungsten Rhenium Osmium Iridium Platinum Gold Mercury (element) Thallium Lead Bismuth Polonium Astatine Radon
Francium Radium Actinium Thorium Protactinium Uranium Neptunium Plutonium Americium Curium Berkelium Californium Einsteinium Fermium Mendelevium Nobelium Lawrencium Rutherfordium Dubnium Seaborgium Bohrium Hassium Meitnerium Darmstadtium Roentgenium Copernicium Nihonium Flerovium Moscovium Livermorium Tennessine Oganesson
Gd

Cm

(Upn)
americiumcuriumberkelium
Atomic number (Z)96
Groupgroup n/a
Periodperiod 7
Blockf-block
Element category  Actinide
Electron configuration[Rn] 5f7 6d1 7s2
Electrons per shell2, 8, 18, 32, 25, 9, 2
Physical properties
Phase at STPsolid
Melting point1613 K ​(1340 °C, ​2444 °F)
Boiling point3383 K ​(3110 °C, ​5630 °F)
Density (near r.t.)13.51 g/cm3
Heat of fusion13.85 kJ/mol
Vapor pressure
P (Pa) 1 10 100 1 k 10 k 100 k
at T (K) 1788 1982
Atomic properties
Oxidation states+2, +3, +4, +5,[1] +6[2] (an amphoteric oxide)
ElectronegativityPauling scale: 1.3
Ionization energies
  • 1st: 581 kJ/mol
Atomic radiusempirical: 174 pm
Covalent radius169±3 pm
Color lines in a spectral range
Spectral lines of curium
Other properties
Natural occurrencesynthetic
Crystal structuredouble hexagonal close-packed (dhcp)
Double hexagonal close packed crystal structure for curium
Electrical resistivity1.25 µΩ·m[3]
Magnetic orderingantiferromagnetic-paramagnetic transition at 52 K[3]
CAS Number7440-51-9
History
Namingnamed after Marie Skłodowska-Curie and Pierre Curie
DiscoveryGlenn T. Seaborg, Ralph A. James, Albert Ghiorso (1944)
Main isotopes of curium
Iso­tope Abun­dance Half-life (t1/2) Decay mode Pro­duct
242Cm syn 160 d SF
α 238Pu
243Cm syn 29.1 y α 239Pu
ε 243Am
SF
244Cm syn 18.1 y SF
α 240Pu
245Cm syn 8500 y SF
α 241Pu
246Cm syn 4730 y α 242Pu
SF
247Cm syn 1.56×107 y α 243Pu
248Cm syn 3.40×105 y α 244Pu
SF
250Cm syn 9000 y SF
α 246Pu
β 250Bk
Category Category: Curium
| references

Curium is a transuranic radioactive chemical element with the 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. The discovery was kept secret and only released to the public in November 1947. 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 the 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 serve as a heat source in radioisotope thermoelectric generators, but this application is hindered by the scarcity and high cost 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 several space probes, including the Sojourner, Spirit, Opportunity and Curiosity Mars rovers and the Philae lander on comet 67P/Churyumov–Gerasimenko, to analyze the composition and structure of the surface.