Polonium

  • polonium, 84po
    polonium.jpg
    polonium
    pronunciationm/ (loh-nee-əm)
    allotropesα, β
    appearancesilvery
    mass number[209]
    polonium 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
    te

    po

    lv
    bismuthpoloniumastatine
    atomic number (z)84
    groupgroup 16 (chalcogens)
    periodperiod 6
    blockp-block
    element category  post-transition metal, but this status is disputed
    electron configuration[xe] 4f14 5d10 6s2 6p4
    electrons per shell2, 8, 18, 32, 18, 6
    physical properties
    phase at stpsolid
    melting point527 k ​(254 °c, ​489 °f)
    boiling point1235 k ​(962 °c, ​1764 °f)
    density (near r.t.)alpha: 9.196 g/cm3
    beta: 9.398 g/cm3
    heat of fusionca. 13 kj/mol
    heat of vaporization102.91 kj/mol
    molar heat capacity26.4 j/(mol·k)
    vapor pressure
    p (pa) 1 10 100 1 k 10 k 100 k
    at t (k) (846) 1003 1236
    atomic properties
    oxidation states−2, +2, +4, +5,[1] +6 (an amphoteric oxide)
    electronegativitypauling scale: 2.0
    ionization energies
    • 1st: 812.1 kj/mol
    atomic radiusempirical: 168 pm
    covalent radius140±4 pm
    van der waals radius197 pm
    color lines in a spectral range
    spectral lines of polonium
    other properties
    natural occurrencefrom decay
    crystal structurecubic
    cubic crystal structure for polonium

    α-po
    crystal structurerhombohedral
    rhombohedral crystal structure for polonium

    β-po
    thermal expansion23.5 µm/(m·k) (at 25 °c)
    thermal conductivity20 w/(m·k) (?)
    electrical resistivityα: 0.40 µΩ·m (at 0 °c)
    magnetic orderingnonmagnetic
    cas number7440-08-6
    history
    namingafter polonia, latin for poland, homeland of marie curie
    discoverypierre and marie curie (1898)
    first isolationwilly marckwald (1902)
    main isotopes of polonium
    iso­tope abun­dance half-life (t1/2) decay mode pro­duct
    208po syn 2.898 y α 204pb
    β+ 208bi
    209po syn 125.2 y[2] α 205pb
    β+ 209bi
    210po trace 138.376 d α 206pb
    category category: polonium
    | references

    polonium is a chemical element with the symbol po and atomic number 84. a rare and highly radioactive metal with no stable isotopes, polonium is chemically similar to selenium and tellurium, though its metallic character resembles that of its horizontal neighbors in the periodic table: thallium, lead, and bismuth. due to the short half-life of all its isotopes, its natural occurrence is limited to tiny traces of the fleeting polonium-210 (with a half-life of 138 days) in uranium ores, as it is the penultimate daughter of natural uranium-238. though slightly longer-lived isotopes exist, they are much more difficult to produce. today, polonium is usually produced in milligram quantities by the neutron irradiation of bismuth. due to its intense radioactivity, which results in the radiolysis of chemical bonds and radioactive self-heating, its chemistry has mostly been investigated on the trace scale only.

    polonium was discovered in 1898 by marie and pierre curie, when it was extracted from the uranium ore pitchblende and identified solely by its strong radioactivity: it was the first element to be so discovered. polonium was named after marie curie's homeland of poland. polonium has few applications, and those are related to its radioactivity: heaters in space probes, antistatic devices, sources of neutrons and alpha particles, and poison. it is a radioactive element and extremely dangerous to humans.

  • characteristics
  • history
  • occurrence and production
  • applications
  • biology and toxicity
  • see also
  • references
  • bibliography
  • external links

Polonium, 84Po
Polonium.jpg
Polonium
Pronunciationm/ (LOH-nee-əm)
Allotropesα, β
Appearancesilvery
Mass number[209]
Polonium 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
Te

Po

Lv
bismuthpoloniumastatine
Atomic number (Z)84
Groupgroup 16 (chalcogens)
Periodperiod 6
Blockp-block
Element category  Post-transition metal, but this status is disputed
Electron configuration[Xe] 4f14 5d10 6s2 6p4
Electrons per shell2, 8, 18, 32, 18, 6
Physical properties
Phase at STPsolid
Melting point527 K ​(254 °C, ​489 °F)
Boiling point1235 K ​(962 °C, ​1764 °F)
Density (near r.t.)alpha: 9.196 g/cm3
beta: 9.398 g/cm3
Heat of fusionca. 13 kJ/mol
Heat of vaporization102.91 kJ/mol
Molar heat capacity26.4 J/(mol·K)
Vapor pressure
P (Pa) 1 10 100 1 k 10 k 100 k
at T (K) (846) 1003 1236
Atomic properties
Oxidation states−2, +2, +4, +5,[1] +6 (an amphoteric oxide)
ElectronegativityPauling scale: 2.0
Ionization energies
  • 1st: 812.1 kJ/mol
Atomic radiusempirical: 168 pm
Covalent radius140±4 pm
Van der Waals radius197 pm
Color lines in a spectral range
Spectral lines of polonium
Other properties
Natural occurrencefrom decay
Crystal structurecubic
Cubic crystal structure for polonium

α-Po
Crystal structurerhombohedral
Rhombohedral crystal structure for polonium

β-Po
Thermal expansion23.5 µm/(m·K) (at 25 °C)
Thermal conductivity20 W/(m·K) (?)
Electrical resistivityα: 0.40 µΩ·m (at 0 °C)
Magnetic orderingnonmagnetic
CAS Number7440-08-6
History
Namingafter Polonia, Latin for Poland, homeland of Marie Curie
DiscoveryPierre and Marie Curie (1898)
First isolationWilly Marckwald (1902)
Main isotopes of polonium
Iso­tope Abun­dance Half-life (t1/2) Decay mode Pro­duct
208Po syn 2.898 y α 204Pb
β+ 208Bi
209Po syn 125.2 y[2] α 205Pb
β+ 209Bi
210Po trace 138.376 d α 206Pb
Category Category: Polonium
| references

Polonium is a chemical element with the symbol Po and atomic number 84. A rare and highly radioactive metal with no stable isotopes, polonium is chemically similar to selenium and tellurium, though its metallic character resembles that of its horizontal neighbors in the periodic table: thallium, lead, and bismuth. Due to the short half-life of all its isotopes, its natural occurrence is limited to tiny traces of the fleeting polonium-210 (with a half-life of 138 days) in uranium ores, as it is the penultimate daughter of natural uranium-238. Though slightly longer-lived isotopes exist, they are much more difficult to produce. Today, polonium is usually produced in milligram quantities by the neutron irradiation of bismuth. Due to its intense radioactivity, which results in the radiolysis of chemical bonds and radioactive self-heating, its chemistry has mostly been investigated on the trace scale only.

Polonium was discovered in 1898 by Marie and Pierre Curie, when it was extracted from the uranium ore pitchblende and identified solely by its strong radioactivity: it was the first element to be so discovered. Polonium was named after Marie Curie's homeland of Poland. Polonium has few applications, and those are related to its radioactivity: heaters in space probes, antistatic devices, sources of neutrons and alpha particles, and poison. It is a radioactive element and extremely dangerous to humans.