Polonium is a chemical element wi the seembol Po an atomic nummer 84, discovered in 1898 bi Marie Curie an Pierre Curie. A rare an heichly radioactive element wi na stable isotopes, polonium is chemically seemilar tae bismuth an tellurium, an it occurs in uranium ores. Applications o polonium are few, an include heaters in space probes, antistatic devices, an soorces o neutrons an alpha particles. Acause o its poseetion in the periodic cairt, polonium is whiles clessifee'd as a metalloid.[3] Ither soorces say that on the basis o its properties an behaviour, it is "unambiguously a metal".[4]

Polonium, 84Po
Polonium
Pronunciation/pəˈlniəm/ (pə-LOH-nee-əm)
Appearancesillery
Mass number[209]
Polonium in the periodic cairt
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 Airn Cobalt Nickel Capper Zinc Gallium Germanium Arsenic Selenium Bromine Krypton
Rubidium Strontium Yttrium Zirconium Niobium Molybdenum Technetium Ruthenium Rhodium Palladium Siller (element) 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 Gowd Mercur (element) Thallium Leid (element) 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 Ununtrium Flerovium Ununpentium Livermorium Ununseptium Ununoctium
Te

Po

Lv
bismuthpoloniumastatine
Atomic nummer (Z)84
Groupgroup 16 (chalcogens)
Periodperiod 6
Blockp-block
Element category  Post-transeetion metal
Electron confeeguration[Xe] 4f14 5d10 6s2 6p4
Electrons per shell2, 8, 18, 32, 18, 6
Pheesical properties
Phase at STPsolit
Meltin pynt527 K ​(254 °C, ​489 °F)
Bylin pynt1235 K ​(962 °C, ​1764 °F)
Density (near r.t.)(alpha) 9.196 g/cm3
(beta) 9.398 g/cm3
Heat o fusionca. 13 kJ/mol
Heat o vapourisation102.91 kJ/mol
Molar heat capacity26.4 J/(mol·K)
Vapour pressur
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
Atomic radiusempirical: 168 pm
Covalent radius140±4 pm
Van der Waals radius197 pm
Colour lines in a spectral range
Spectral lines o polonium
Ither properties
Creestal structurcubic
Cubic creestal structur for polonium
Thermal expansion23.5 µm/(m·K) (at 25 °C)
Thermal conductivity? 20 W/(m·K)
Electrical resistivity(α) 0.40 µ Ω·m (at 0 °C)
Magnetic orderinnonmagnetic
CAS Nummer7440-08-6
History
DiskiveryPierre Curie an Marie Curie (1898)
First isolationWilly Marckwald (1902)
Main isotopes o polonium
Iso­tope Abun­dance Hauf-life (t1/2) Decay mode Pro­duct
208Po syn 2.898 y α 204Pb
β+ 208Bi
209Po syn 103 y α 205Pb
β+ 209Bi
210Po trace 138.376 d α 206Pb
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ReferencesEedit

  1. Thayer, John S. (2010). "Relativistic Effects and the Chemistry of the Heavier Main Group Elements". Relativistic Methods for Chemists: 78. doi:10.1007/978-1-4020-9975-5_2. ISBN 978-1-4020-9974-8.
  2. Thayer, John S. (2010). Chemistry of heavier main group elements. p. 78. doi:10.1007/9781402099755_2.
  3. "Characterizing the Elements". Los Alamos National Laboratory. Retrieved 4 March 2013.
  4. Hawkes, Stephen J. (2010). "Polonium and Astatine Are Not Semimetals". Journal of Chemical Education. 87 (8): 783. Bibcode:2010JChEd..87..783H. doi:10.1021/ed100308w.