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About Polonium

Polonium Bohr

Polonium was discovered by Marie and Pierre Curie in 1898 – the first new element discovered through the reduction of uranium ores, or pitchblende. It is relatively scarce in the Earth, as only 100 micrograms of polonium can be produced from one ton of uranium ore. The discovery of this element was predicated on the finding that after removing uranium and thorium from ore, the resulting material was actually more radioactive than the uranium or thorium itself. Because of its scarcity, polonium is now produced primarily through neutron bombardment of bismuth (209Bi) in a nuclear reactor. This bombardment creates 210Bi, and after decaying with a half-life of 5 days, and after decay, the resulting material is left as 210Po. Like many other radioactive elements, 210Po is used in radioisotope thermoelectric generators and had a hand in the Manhattan Project. Along with beryllium, polonium was one of the key ingredients in the detonator for the plutonium bomb, “Fat Man”.

Additional applications of polonium include its use as a characteristic neutron source, and use in antistatic devices for industry. When rolling paper, wire or sheet metal, static electricity is often generated. A particle emitter such as polonium is often present in specifically designed brushes to minimize this static electricity, though industry has mostly replaced polonium with less harmful beta particle emitters. Special care must be taken with industrial processes when using polonium in this fashion. Additionally, polonium is utilized in applications with comparable necessities, for example: brushes to remove dust from photographic film and camera lenses. Because of its short half-life, these industrial tools need to be replaced on a regular basis. Traces of 210Po can often be found in cigarettes, agricultural phosphate fertilizers, seafood, and even in trace amounts in indoor air. Of the 15,000-22,000 estimated lung cancer deaths in the United States every year attributed to radon, polonium is present in (and presumed to be the cause of) the majority of these cases.

Polonium, a metalloid, can readily create compounds with many other elements; however, most all polonium compounds are synthetically created with little applicability outside of the scientific community. Polonium has 33 isotopes observed in total, all of which are radioactive. The most stable isotope is 209Po with a half-life of 103 years, which then decays into lead through alpha decay. However, the most common isotopes of polonium are found widespread throughout Earth’s biosphere (in trace amounts), and is part of the naturally-occurring uranium decay chain.

Polonium Properties

Polonium Bohr ModelPolonium is a Block P, Group 16, Period 6 element. The number of electrons in each of polonium's shells is 2, 8, 18, 32, 18, 6 and its electron configuration is [Xe]6s24f145d106p4. The polonium atom has a radius of a measure of the size of its atoms, usually the mean or typical distance from the nucleus to the boundary of the surrounding cloud of electrons. Since the boundary is not a well-defined physical entity, there are various non-equivalent definitions of atomic radius. It is measured in picometres (pm)"> 168pm and its Van der Waals radius is 197pm. In its elemental form, CAS 7440-08-6, polonium has a silvery gray appearance. Polonium was first discovered by Madame Marie Curie and and Pierre Curie in 1898 who extracted it from pitchblende, a then known uranium source. Polonium is named after Madame Curie's birthplace of Poland. Polonium is produced during the decay of naturally occurring uranium-238. It has 33 isotopes, all of which are radioactive. Polonium 210 is a radioactive element with a half life of approximately 138.39 days. It occurs naturally and is widely distributed in small amounts in the earth's crust. Polonium's most stable isotope is Polonium 209 with a half life of 102 years. Polonium is now commercially produced by neutron bombardment of bismuth 209 isotopes.

Polonium-210 has been used as a heat source to power thermoelectric cells in satellites. Polonium-210 mixed or alloyed with beryllium is used in neutron sources. Polonium is also used to eliminate static electricity in machinery and to remove dust from camera lenses and film. Polonium is both toxic and radioactive. Polonium information, including properties, research, applications and other useful facts are discussed below. Scientific facts such as the atomic structure, ionization energy, abundance on earth, conductivity and thermal properties are also included.

Symbol: Po
Atomic Number: 84
Atomic Weight: 209
Element Category: post-transition metal
Group, Period, Block: 16 (chalcogens), 6, p
Color: silvery-gray/ silvery
Other Names: N/A
Melting Point: 254 °C, 489 °F, 527 K
Boiling Point: 962 °C, 1764 °F, 1235 K
Density: (alpha) 9.196 g·cm3
Liquid Density @ Melting Point: N/A
Density @ 20°C: 9.4 g/cm3
Density of Solid: 9196 kg·m3
Specific Heat: N/A
Superconductivity Temperature: N/A
Triple Point: N/A
Critical Point: N/A
Heat of Fusion (kJ·mol-1): 10
Heat of Vaporization (kJ·mol-1): 100.8
Heat of Atomization (kJ·mol-1): 141
Thermal Conductivity:  ? 20 W·m-1·K-1
Thermal Expansion: (25 °C) 23.5 µm·m-1·K-1
Electrical Resistivity: (0 °C) (?) 0.40 nΩ·m
Tensile Strength: N/A
Molar Heat Capacity: 26.4 J·mol-1·K-1
Young's Modulus: N/A
Shear Modulus: N/A
Bulk Modulus: N/A
Poisson Ratio: N/A
Mohs Hardness: N/A
Vickers Hardness: N/A
Brinell Hardness: N/A
Speed of Sound: N/A
Pauling Electronegativity: 2
Sanderson Electronegativity: N/A
Allred Rochow Electronegativity: 1.76
Mulliken-Jaffe Electronegativity: 2.48 (16.7% s orbital)
Allen Electronegativity: N/A
Pauling Electropositivity: 2
Reflectivity (%): N/A
Refractive Index: N/A
Chemical Properties
Electrons: 84
Protons: 84
Neutrons: 125
Electron Configuration: [Xe]6s24f145d106p4
Atomic Radius: 168 pm
Atomic Radius,
non-bonded (Å):
Covalent Radius: 140±4 pm
Covalent Radius (Å): 1.42
Van der Waals Radius: 197 pm
Oxidation States: 6, 4, 2, 2 (amphoteric oxide)
Phase: Solid
Crystal Structure: cubic
Magnetic Ordering: nonmagnetic
Electron Affinity (kJ·mol-1) 183.322
1st Ionization Energy: 812.1 kJ·mol-1
2nd Ionization Energy: N/A
3rd Ionization Energy: N/A
CAS Number: 7440-08-6
EC Number: N/A
MDL Number: N/A
Beilstein Number: N/A
SMILES Identifier: [Po]
InChI Identifier: InChI=1S/Po
PubChem CID: 6328143
ChemSpider ID: 4886482
Earth - Total: N/A
Mercury - Total: N/A
Venus - Total: N/A
Earth - Seawater (Oceans), ppb by weight: 2.00E-11
Earth - Seawater (Oceans), ppb by atoms: 6.00E-13
Earth -  Crust (Crustal Rocks), ppb by weight: N/A
Earth -  Crust (Crustal Rocks), ppb by atoms: N/A
Sun - Total, ppb by weight: N/A
Sun - Total, ppb by atoms: N/A
Stream, ppb by weight: N/A
Stream, ppb by atoms: N/A
Meterorite (Carbonaceous), ppb by weight: N/A
Meterorite (Carbonaceous), ppb by atoms: N/A
Typical Human Body, ppb by weight: N/A
Typical Human Body, ppb by atom: N/A
Universe, ppb by weight: N/A
Universe, ppb by atom: N/A
Discovered By: Pierre Curie and Marie Curie
Discovery Date: 1898
First Isolation: Willy Marckwald (1902)

Polonium Isotopes

Polonium (Po) has 33 isotopes, all of which are radioactive.

Nuclide Isotopic Mass Half-Life Mode of Decay Nuclear Spin Magnetic Moment Binding Energy (MeV) Natural Abundance
(% by atom)
188Po187.999422(21)430(180) µs [0.40(+20-15) ms]Unknown0+N/A1433.86-
189Po188.998481(24)5(1) msUnknown3/2-#N/A1441.94-
190Po189.995101(14)2.46(5) msa to 186Pb; ß+ to 190Bi0+N/A1450.02-
191Po190.994574(12)22(1) msa to 187Pb; ß+ to 191Bi3/2-#N/A1458.1-
192Po191.991335(13)32.2(3) msa to 188Pb; ß+ to 192Bi0+N/A1466.17-
193Po192.99103(4)420(40) ms [370(+46-40) ms]a to 189Pb; ß+ to 193Bi3/2-#N/A1474.25-
194Po193.988186(13)0.392(4) sa to 190Pb; ß+ to 194Bi0+N/A1491.65-
195Po194.98811(4)4.64(9) sa to 191Pb; ß+ to 195Bi; IT3/2-#N/A1499.73-
196Po195.985535(14)5.56(12) sa to 192Pb; ß+ to 196Bi0+N/A1507.81-
197Po196.98566(5)53.6(10) sß+ to 197Bi; a to 193Pb(3/2-)N/A1515.88-
198Po197.983389(19)1.77(3) mina to 194Pb; ß+ to 198Bi0+N/A1523.96-
199Po198.983666(25)5.48(16) minß+ to 199Bi; a to 195Pb(3/2-)N/A1532.04-
200Po199.981799(15)11.5(1) minß+ to 200Bi; a to 196Pb0+N/A1540.12-
201Po200.982260(6)15.3(2) minß+ to 201Bi; a to 197Pb3/2-N/A1548.2-
202Po201.980758(16)44.7(5) minß+ to 202Bi; a to 198Pb0+N/A1556.28-
203Po202.981420(28)36.7(5) minß+ to 203Bi; a to 199Pb5/2-N/A1564.36-
204Po203.980318(12)3.53(2) hß+ to 204Bi; a to 200Pb0+N/A1572.44-
205Po204.981203(21)1.66(2) hß+ to 205Bi; a to 201Pb5/2-N/A1580.51-
206Po205.980481(9)8.8(1) dEC to 206Bi; a to 202Pb0+N/A1588.59-
207Po206.981593(7)5.80(2) hEC to 207Bi; a to 203Pb5/2-0.791596.67-
208Po207.9812457(19)2.898(2) yEC to 208Bi; a to 204Pb0+N/A1604.75-
209Po208.9824304(20)102(5) yEC to 209Bi; a to 205Pb1/2-0.771612.83-
210Po209.9828737(13)138.376(2) da to 206Pb0+N/A1620.91-
211Po210.9866532(14)0.516(3) sa to 207Pb9/2+N/A1628.99-
212Po211.9888680(13)299(2) nsa to 208Pb0+N/A1637.07-
213Po212.992857(3)3.65(4) µsa to 209Pb9/2+N/A1635.83-
214Po213.9952014(16)164.3(20) µsa to 210Pb0+N/A1643.91-
215Po214.9994200(27)1.781(4) msa to 211Pb; ß- to 215Bi9/2+N/A1651.98-
216Po216.0019150(24)0.145(2) sa to 212Pb; ß- to 216Bi0+N/A1650.75-
217Po217.006335(7)1.47(5) sa to 213Pb; ß- to 217Bi5/2+#N/A1658.83-
218Po218.0089730(26)3.10(1) mina to 214Pb; ß- to 218Bi0+N/A1666.9-
219Po219.01374(39)#2# min [>300 ns]Unknown7/2+#N/A1665.67-
220Po220.01660(39)#40# s [>300 ns]Unknown0+N/A1673.75-