Actinium

  • actinium, 89ac
    actinium sample (31481701837).png
    actinium
    pronunciationm/ (tin-ee-əm)
    appearancesilvery-white, glowing with an eerie blue light;[1] sometimes with a golden cast[2]
    mass number[227]
    actinium 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
    la

    ac

    (ubu)
    radiumactiniumthorium
    atomic number (z)89
    groupgroup 3
    periodperiod 7
    blockd-block
    element category  actinide, sometimes considered a transition metal
    electron configuration[rn] 6d1 7s2
    electrons per shell2, 8, 18, 32, 18, 9, 2
    physical properties
    phase at stpsolid
    melting point1500 k ​(1227 °c, ​2240 °f) (estimated)[2]
    boiling point3500±300 k ​(3200±300 °c, ​5800±500 °f) (extrapolated)[2]
    density (near r.t.)10 g/cm3
    heat of fusion14 kj/mol
    heat of vaporization400 kj/mol
    molar heat capacity27.2 j/(mol·k)
    atomic properties
    oxidation states+2, +3 (a strongly basic oxide)
    electronegativitypauling scale: 1.1
    ionization energies
    • 1st: 499 kj/mol
    • 2nd: 1170 kj/mol
    • 3rd: 1900 kj/mol
    • (more)
    covalent radius215 pm
    color lines in a spectral range
    spectral lines of actinium
    other properties
    natural occurrencefrom decay
    crystal structureface-centered cubic (fcc)
    face-centered cubic crystal structure for actinium
    thermal conductivity12 w/(m·k)
    cas number7440-34-8
    history
    discovery and first isolationfriedrich oskar giesel (1902)
    named byandré-louis debierne (1899)
    main isotopes of actinium
    iso­tope abun­dance half-life (t1/2) decay mode pro­duct
    225ac trace 10 d α 221fr
    226ac syn 29.37 h β 226th
    ε 226ra
    α 222fr
    227ac trace 21.772 y β 227th
    α 223fr
    category category: actinium
    | references

    actinium is a chemical element with the symbol ac and atomic number 89. it was first isolated by french chemist andré-louis debierne in 1899. friedrich oskar giesel later independently isolated it in 1902 and, unaware that it was already known, gave it the name emanium.[3] actinium gave the name to the actinide series, a group of 15 similar elements between actinium and lawrencium in the periodic table. it is also sometimes considered the first of the 7th-period transition metals, although lawrencium is less commonly given that position. together with polonium, radium, and radon, actinium was one of the first non-primordial radioactive elements to be isolated.

    a soft, silvery-white radioactive metal, actinium reacts rapidly with oxygen and moisture in air forming a white coating of actinium oxide that prevents further oxidation. as with most lanthanides and many actinides, actinium assumes oxidation state +3 in nearly all its chemical compounds. actinium is found only in traces in uranium and thorium ores as the isotope 227ac, which decays with a half-life of 21.772 years, predominantly emitting beta and sometimes alpha particles, and 228ac, which is beta active with a half-life of 6.15 hours. one tonne of natural uranium in ore contains about 0.2 milligrams of actinium-227, and one tonne of thorium contains about 5 nanograms of actinium-228. the close similarity of physical and chemical properties of actinium and lanthanum makes separation of actinium from the ore impractical. instead, the element is prepared, in milligram amounts, by the neutron irradiation of 226ra in a nuclear reactor. owing to its scarcity, high price and radioactivity, actinium has no significant industrial use. its current applications include a neutron source and an agent for radiation therapy.

  • history
  • properties
  • chemical compounds
  • isotopes
  • occurrence and synthesis
  • applications
  • precautions
  • see also
  • references
  • bibliography
  • external links

Actinium, 89Ac
Actinium sample (31481701837).png
Actinium
Pronunciationm/ (TIN-ee-əm)
Appearancesilvery-white, glowing with an eerie blue light;[1] sometimes with a golden cast[2]
Mass number[227]
Actinium 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
La

Ac

(Ubu)
radiumactiniumthorium
Atomic number (Z)89
Groupgroup 3
Periodperiod 7
Blockd-block
Element category  Actinide, sometimes considered a transition metal
Electron configuration[Rn] 6d1 7s2
Electrons per shell2, 8, 18, 32, 18, 9, 2
Physical properties
Phase at STPsolid
Melting point1500 K ​(1227 °C, ​2240 °F) (estimated)[2]
Boiling point3500±300 K ​(3200±300 °C, ​5800±500 °F) (extrapolated)[2]
Density (near r.t.)10 g/cm3
Heat of fusion14 kJ/mol
Heat of vaporization400 kJ/mol
Molar heat capacity27.2 J/(mol·K)
Atomic properties
Oxidation states+2, +3 (a strongly basic oxide)
ElectronegativityPauling scale: 1.1
Ionization energies
  • 1st: 499 kJ/mol
  • 2nd: 1170 kJ/mol
  • 3rd: 1900 kJ/mol
  • (more)
Covalent radius215 pm
Color lines in a spectral range
Spectral lines of actinium
Other properties
Natural occurrencefrom decay
Crystal structureface-centered cubic (fcc)
Face-centered cubic crystal structure for actinium
Thermal conductivity12 W/(m·K)
CAS Number7440-34-8
History
Discovery and first isolationFriedrich Oskar Giesel (1902)
Named byAndré-Louis Debierne (1899)
Main isotopes of actinium
Iso­tope Abun­dance Half-life (t1/2) Decay mode Pro­duct
225Ac trace 10 d α 221Fr
226Ac syn 29.37 h β 226Th
ε 226Ra
α 222Fr
227Ac trace 21.772 y β 227Th
α 223Fr
Category Category: Actinium
| references

Actinium is a chemical element with the symbol Ac and atomic number 89. It was first isolated by French chemist André-Louis Debierne in 1899. Friedrich Oskar Giesel later independently isolated it in 1902 and, unaware that it was already known, gave it the name emanium.[3] Actinium gave the name to the actinide series, a group of 15 similar elements between actinium and lawrencium in the periodic table. It is also sometimes considered the first of the 7th-period transition metals, although lawrencium is less commonly given that position. Together with polonium, radium, and radon, actinium was one of the first non-primordial radioactive elements to be isolated.

A soft, silvery-white radioactive metal, actinium reacts rapidly with oxygen and moisture in air forming a white coating of actinium oxide that prevents further oxidation. As with most lanthanides and many actinides, actinium assumes oxidation state +3 in nearly all its chemical compounds. Actinium is found only in traces in uranium and thorium ores as the isotope 227Ac, which decays with a half-life of 21.772 years, predominantly emitting beta and sometimes alpha particles, and 228Ac, which is beta active with a half-life of 6.15 hours. One tonne of natural uranium in ore contains about 0.2 milligrams of actinium-227, and one tonne of thorium contains about 5 nanograms of actinium-228. The close similarity of physical and chemical properties of actinium and lanthanum makes separation of actinium from the ore impractical. Instead, the element is prepared, in milligram amounts, by the neutron irradiation of 226Ra in a nuclear reactor. Owing to its scarcity, high price and radioactivity, actinium has no significant industrial use. Its current applications include a neutron source and an agent for radiation therapy.