Isotopes of polonium

Polonium (84Po) has 42 isotopes, all of which are radioactive, with between 186 and 227 nucleons. 210Po with a half-life of 138.376 days has the longest half-life of naturally occurring polonium. 209Po with a half-life of 125 years has the longest half-life of all isotopes of polonium. 209Po and 208Po (half-life 2.9 years) can be made through proton bombardment of bismuth in a cyclotron.[2]

Main isotopes of polonium (84Po)
Iso­tope Decay
abun­dance half-life (t1/2) mode pro­duct
208Po syn 2.898 y α 204Pb
β+ 208Bi
209Po syn (125.2±3.3) y[1] α 205Pb
β+ 209Bi
210Po trace 138.376 d α 206Pb


210Po is an alpha emitter that has a half-life of 138.376 days; it decays directly to stable 206Pb. A milligram of 210Po emits as many alpha particles per second as 5 grams of 226Ra.[3] A few curies (1 curie equals 37 gigabecquerels) of 210Po emit a blue glow caused by excitation of surrounding air. A single gram of 210Po generates 140 watts of power.[4] Because it emits many alpha particles, which are stopped within a very short distance in dense media and release their energy, 210Po has been used as a lightweight heat source to power thermoelectric cells in artificial satellites; for instance, a 210Po heat source was also in each of the Lunokhod rovers deployed on the surface of the Moon, to keep their internal components warm during the lunar nights.[5] Some anti-static brushes, used for neutralizing static electricity on materials like photographic film, contain a few microcuries of 210Po as a source of charged particles.[6] 210Po was also used in initiators for atomic bombs through the (α,n) reaction with beryllium.[7]

The majority of the time 210Po decays by emission of an alpha particle only, not by emission of an alpha particle and a gamma ray. About one in 100,000 decays results in the emission of a gamma ray.[8] This low gamma ray production rate makes it more difficult to find and identify this isotope. Rather than gamma ray spectroscopy, alpha spectroscopy is the best method of measuring this isotope.

210Po occurs in minute amounts in nature, where it is an intermediate isotope in the uranium series decay chain. It is generated via beta decay from 210Pb and 210Bi. In the environment, 210Po can accumulate in seafood.[9]

210Po is extremely toxic, with one microgram being enough to kill the average adult (250,000 times more toxic than hydrogen cyanide by weight).[10] 210Po was used to kill Russian dissident and ex-FSB officer Alexander V. Litvinenko in 2006,[11] and was suspected as a possible cause of Yasser Arafat's death, following exhumation and analysis of his corpse in 2012–2013.[12]

List of isotopes

isotopic mass (u)
[19][n 1]
[n 2]
spin and
(mole fraction)
range of natural
(mole fraction)
excitation energy
186Po 84 102 186.0044(18) 34(12) µs
α 182Pb 0+
187Po 84 103 187.00304(30) 1.40(0.25) ms
α 183Pb (1/2-, 5/2-)
187mPo 4(27) keV 0.5 ms 13/2+#
188Po 84 104 187.999422(21) 430(180) µs
[0.40(+20−15) ms]
α 184Pb 0+
189Po 84 105 188.998481(24) 5(1) ms α 185Pb 3/2−#
190Po 84 106 189.995101(14) 2.46(5) ms α (99.9%) 186Pb 0+
β+ (.1%) 190Bi
191Po 84 107 190.994574(12) 22(1) ms α 187Pb 3/2−#
β+ (rare) 191Bi
191mPo 130(21) keV 93(3) ms (13/2+)
192Po 84 108 191.991335(13) 32.2(3) ms α (99%) 188Pb 0+
β+ (1%) 192Bi
192mPo 2600(500)# keV ~1 µs 12+#
193Po 84 109 192.99103(4) 420(40) ms
[370(+46−40) ms]
α 189Pb 3/2−#
β+ (rare) 193Bi
193mPo 100(30)# keV 240(10) ms
[243(+11−10) ms]
α 189Pb (13/2+)
β+ (rare) 193Bi
194Po 84 110 193.988186(13) 0.392(4) s α 190Pb 0+
β+ (rare) 194Bi
194mPo 2525(2) keV 15(2) µs (11−)
195Po 84 111 194.98811(4) 4.64(9) s α (75%) 191Pb 3/2−#
β+ (25%) 195Bi
195mPo 110(50) keV 1.92(2) s α (90%) 191Pb 13/2+#
β+ (10%) 195Bi
IT (.01%) 195Po
196Po 84 112 195.985535(14) 5.56(12) s α (94%) 192Pb 0+
β+ (6%) 196Bi
196mPo 2490.5(17) keV 850(90) ns (11−)
197Po 84 113 196.98566(5) 53.6(10) s β+ (54%) 197Bi (3/2−)
α (44%) 193Pb
197mPo 230(80)# keV 25.8(1) s α (84%) 193Pb (13/2+)
β+ (16%) 197Bi
IT (.01%) 197Po
198Po 84 114 197.983389(19) 1.77(3) min α (57%) 194Pb 0+
β+ (43%) 198Bi
198m1Po 2565.92(20) keV 200(20) ns 11−
198m2Po 2691.86(20) keV 750(50) ns 12+
199Po 84 115 198.983666(25) 5.48(16) min β+ (92.5%) 199Bi (3/2−)
α (7.5%) 195Pb
199mPo 312.0(28) keV 4.17(4) min β+ (73.5%) 199Bi 13/2+
α (24%) 195Pb
IT (2.5%) 199Po
200Po 84 116 199.981799(15) 11.5(1) min β+ (88.8%) 200Bi 0+
α (11.1%) 196Pb
201Po 84 117 200.982260(6) 15.3(2) min β+ (98.4%) 201Bi 3/2−
α (1.6%) 197Pb
201mPo 424.1(24) keV 8.9(2) min IT (56%) 201Po 13/2+
EC (41%) 201Bi
α (2.9%) 197Pb
202Po 84 118 201.980758(16) 44.7(5) min β+ (98%) 202Bi 0+
α (2%) 198Pb
202mPo 2626.7(7) keV >200 ns 11−
203Po 84 119 202.981420(28) 36.7(5) min β+ (99.89%) 203Bi 5/2−
α (.11%) 199Pb
203m1Po 641.49(17) keV 45(2) s IT (99.96%) 203Po 13/2+
α (.04%) 199Pb
203m2Po 2158.5(6) keV >200 ns
204Po 84 120 203.980318(12) 3.53(2) h β+ (99.33%) 204Bi 0+
α (.66%) 200Pb
205Po 84 121 204.981203(21) 1.66(2) h β+ (99.96%) 205Bi 5/2−
α (.04%) 201Pb
205m1Po 143.166(17) keV 310(60) ns 1/2−
205m2Po 880.30(4) keV 645 µs 13/2+
205m3Po 1461.21(21) keV 57.4(9) ms IT 205Po 19/2−
205m4Po 3087.2(4) keV 115(10) ns 29/2−
206Po 84 122 205.980481(9) 8.8(1) d β+ (94.55%) 206Bi 0+
α (5.45%) 202Pb
206m1Po 1585.85(11) keV 222(10) ns (8+)#
206m2Po 2262.22(14) keV 1.05(6) µs (9−)#
207Po 84 123 206.981593(7) 5.80(2) h β+ (99.97%) 207Bi 5/2−
α (.021%) 203Pb
207m1Po 68.573(14) keV 205(10) ns 1/2−
207m2Po 1115.073(16) keV 49(4) µs 13/2+
207m3Po 1383.15(6) keV 2.79(8) s IT 207Po 19/2−
208Po 84 124 207.9812457(19) 2.898(2) y α (99.99%) 204Pb 0+
β+ (.00277%) 208Bi
209Po 84 125 208.9824304(20) 125.2(3.3) y[20] α (99.52%) 205Pb 1/2−
β+ (.48%) 209Bi
210Po Radium F 84 126 209.9828737(13) 138.376(2) d α 206Pb 0+ Trace[n 3]
210mPo 5057.61(4) keV 263(5) ns 16+
211Po Actinium C' 84 127 210.9866532(14) 0.516(3) s α 207Pb 9/2+ Trace[n 4]
211m1Po 1462(5) keV 25.2(6) s α (99.98%) 207Pb (25/2+)
IT (.016%) 211Po
211m2Po 2135.7(9) keV 243(21) ns (31/2−)
211m3Po 4873.3(17) keV 2.8(7) µs (43/2+)
212Po Thorium C' 84 128 211.9888680(13) 299(2) ns α 208Pb 0+ Trace[n 5]
212mPo 2911(12) keV 45.1(6) s α (99.93%) 208Pb (18+)
IT (.07%) 212Po
213Po 84 129 212.992857(3) 3.65(4) µs α 209Pb 9/2+
214Po Radium C' 84 130 213.9952014(16) 164.3(20) µs α 210Pb 0+ Trace[n 3]
215Po Actinium A 84 131 214.9994200(27) 1.781(4) ms α (99.99%) 211Pb 9/2+ Trace[n 4]
β (2.3×10−4%) 215At
216Po Thorium A 84 132 216.0019150(24) 0.145(2) s α 212Pb 0+ Trace[n 5]
ββ (rare) 216Rn
217Po 84 133 217.006335(7) 1.47(5) s α (95%) 213Pb 5/2+#
β (5%) 217At
218Po Radium A 84 134 218.0089730(26) 3.10(1) min α (99.98%) 214Pb 0+ Trace[n 3]
β (.02%) 218At
219Po 84 135 219.01361(16) 10.3(1) min α (28.2%) 215Pb 9/2+#
β (71.8%) 219At
220Po 84 136 220.0164(18) 40# s
[>300 ns]
β 220At 0+
221Po 84 137 221.02123(20) 2.2(0.7) min β 221At 9/2+#
222Po 84 138 222.024144(40) 9.1(7.2) min β 222At 0+
  1. ^ Abbreviations:
    EC: Electron capture
    IT: Isomeric transition
  2. ^ Bold for stable isotopes, bold italics for nearly stable isotopes (half-life longer than the age of the universe)
  3. ^ a b c Intermediate decay product of Uranium-238
  4. ^ a b Intermediate decay product of Uranium-235
  5. ^ a b Intermediate decay product of Thorium-232


  • Values marked # are not purely derived from experimental data, but at least partly from systematic trends. Spins with weak assignment arguments are enclosed in parentheses.
  • Uncertainties are given in concise form in parentheses after the corresponding last digits. Uncertainty values denote one standard deviation, except isotopic composition and standard atomic mass from IUPAC, which use expanded uncertainties.
  • Half-life abbreviations are y=year, d=day, min=minute, s=second, ms=millisecond, µs=microsecond, ns=nanosecond.
  • A superscripted m (or m2, etc.) refers to an isomer of that particular isotope.


  1. ^ Boutin, Chad. "Polonium's Most Stable Isotope Gets Revised Half-Life Measurement". NIST Tech Beat. Retrieved 9 September 2014.
  2. ^ Carvalho, F.; Fernandes, S.; Fesenko, S.; Holm, E.; Howard, B.; Martin, P.; Phaneuf, P.; Porcelli, D.; Pröhl, G.; Twining, J. (2017). The Environmental Behaviour of Polonium. Technical reports series. 484. Vienna: International Atomic Energy Agency. p. 22. ISBN 978-92-0-112116-5. ISSN 0074-1914.
  3. ^ C. R. Hammond. "The Elements" (PDF). Fermi National Accelerator Laboratory. pp. 4–22.
  4. ^ "Polonium" (PDF). Argonne National Laboratory. Archived from the original (PDF) on 2012-03-10.
  5. ^ Andrew Wilson, Solar System Log, (London: Jane's Publishing Company Ltd, 1987), p. 64.
  6. ^ "Staticmaster Alpha Ionizing Brush". Company 7.
  7. ^ Lillian Hoddeson; Paul W. Henriksen; Roger A. Meade (12 February 2004). Critical Assembly: A Technical History of Los Alamos During the Oppenheimer Years, 1943-1945. Cambridge University Press. ISBN 978-0-521-54117-6.
  8. ^ 210PO A DECAY Archived February 24, 2015, at the Wayback Machine
  9. ^ Richter, F.; Wagmann, M.; Zehringer, M. (2012). "Polonium – on the Trace of a Powerful Alpha Nuclide in the Environment". CHIMIA International Journal for Chemistry. 66 (3): 131. doi:10.2533/chimia.2012.131.
  10. ^ Sublette, Carey. "Polonium Poisoning".
  11. ^ Cowell, Alan (November 24, 2006). "Radiation Poisoning Killed Ex-Russian Spy". The New York Times.
  12. ^ "Arafat's death: what is Polonium-210?". Al Jazeera. July 10, 2012.
  13. ^ a b de Laeter, John Robert; Böhlke, John Karl; De Bièvre, Paul; Hidaka, Hiroshi; Peiser, H. Steffen; Rosman, Kevin J. R.; Taylor, Philip D. P. (2003). "Atomic weights of the elements. Review 2000 (IUPAC Technical Report)". Pure and Applied Chemistry. 75 (6): 683–800. doi:10.1351/pac200375060683.
  14. ^ a b Wieser, Michael E. (2006). "Atomic weights of the elements 2005 (IUPAC Technical Report)". Pure and Applied Chemistry. 78 (11): 2051–2066. doi:10.1351/pac200678112051. Lay summary.
  15. ^ a b Audi, Georges; Bersillon, Olivier; Blachot, Jean; Wapstra, Aaldert Hendrik (2003), "The NUBASE evaluation of nuclear and decay properties", Nuclear Physics A, 729: 3–128, Bibcode:2003NuPhA.729....3A, doi:10.1016/j.nuclphysa.2003.11.001
  16. ^ Audi, Georges; Kondev, Filip G.; Wang, Meng; Huang, Wen Jia; Naimi, Sarah (2017), "The NUBASE2016 evaluation of nuclear properties" (PDF), Chinese Physics C, 41 (3): 030001–1—030001–138, Bibcode:2017ChPhC..41c0001A, doi:10.1088/1674-1137/41/3/030001
  17. ^ a b National Nuclear Data Center. "NuDat 2.x database". Brookhaven National Laboratory.
  18. ^ a b Holden, Norman E. (2004). "11. Table of the Isotopes". In Lide, David R. (ed.). CRC Handbook of Chemistry and Physics (85th ed.). Boca Raton, Florida: CRC Press. ISBN 978-0-8493-0485-9.
  19. ^ "Universal Nuclide Chart". nucleonica.
  20. ^ Boutin, Chad (2014-09-09). "Polonium's Most Stable Isotope Gets Revised Half-Life Measurement". NIST Tech Beat. Retrieved 9 September 2014.

See also


The chalcogens () are the chemical elements in group 16 of the periodic table. This group is also known as the oxygen family. It consists of the elements oxygen (O), sulfur (S), selenium (Se), tellurium (Te), and the radioactive element polonium (Po). The chemically uncharacterized synthetic element livermorium (Lv) is predicted to be a chalcogen as well. Often, oxygen is treated separately from the other chalcogens, sometimes even excluded from the scope of the term "chalcogen" altogether, due to its very different chemical behavior from sulfur, selenium, tellurium, and polonium. The word "chalcogen" is derived from a combination of the Greek word khalkόs (χαλκός) principally meaning copper (the term was also used for bronze/brass, any metal in the poetic sense, ore or coin), and the Latinised Greek word genēs, meaning born or produced.Sulfur has been known since antiquity, and oxygen was recognized as an element in the 18th century. Selenium, tellurium and polonium were discovered in the 19th century, and livermorium in 2000. All of the chalcogens have six valence electrons, leaving them two electrons short of a full outer shell. Their most common oxidation states are −2, +2, +4, and +6. They have relatively low atomic radii, especially the lighter ones.Lighter chalcogens are typically nontoxic in their elemental form, and are often critical to life, while the heavier chalcogens are typically toxic. All of the chalcogens have some role in biological functions, either as a nutrient or a toxin. The lighter chalcogens, such as oxygen and sulfur, are rarely toxic and usually helpful in their pure form. Selenium is an important nutrient but is also commonly toxic. Tellurium often has unpleasant effects (although some organisms can use it), and polonium is always extremely harmful, both in its chemical toxicity and its radioactivity.

Sulfur has more than 20 allotropes, oxygen has nine, selenium has at least five, polonium has two, and only one crystal structure of tellurium has so far been discovered. There are numerous organic chalcogen compounds. Not counting oxygen, organic sulfur compounds are generally the most common, followed by organic selenium compounds and organic tellurium compounds. This trend also occurs with chalcogen pnictides and compounds containing chalcogens and carbon group elements.

Oxygen is generally extracted from air and sulfur is extracted from oil and natural gas. Selenium and tellurium are produced as byproducts of copper refining. Polonium and livermorium are most available in particle accelerators. The primary use of elemental oxygen is in steelmaking. Sulfur is mostly converted into sulfuric acid, which is heavily used in the chemical industry. Selenium's most common application is glassmaking. Tellurium compounds are mostly used in optical disks, electronic devices, and solar cells. Some of polonium's applications are due to its radioactivity.

Natural gas

Natural gas (also called fossil gas) is a naturally occurring hydrocarbon gas mixture consisting primarily of methane, but commonly including varying amounts of other higher alkanes, and sometimes a small percentage of carbon dioxide, nitrogen, hydrogen sulfide, or helium. It is formed when layers of decomposing plant and animal matter are exposed to intense heat and pressure under the surface of the Earth over millions of years. The energy that the plants originally obtained from the sun is stored in the form of chemical bonds in the gas.Natural gas is a non-renewable hydrocarbon used as a source of energy for heating, cooking, and electricity generation. It is also used as a fuel for vehicles and as a chemical feedstock in the manufacture of plastics and other commercially important organic chemicals.

Natural gas is a major cause of global warming, both in itself when leaked and also due to the carbon dioxide it produces when burnt.Natural gas is found in deep underground rock formations or associated with other hydrocarbon reservoirs in coal beds and as methane clathrates. Petroleum is another resource and fossil fuel found in close proximity to and with natural gas. Most natural gas was created over time by two mechanisms: biogenic and thermogenic. Biogenic gas is created by methanogenic organisms in marshes, bogs, landfills, and shallow sediments. Deeper in the earth, at greater temperature and pressure, thermogenic gas is created from buried organic material.In petroleum production gas is sometimes burnt as flare gas. Before natural gas can be used as a fuel, most, but not all, must be processed to remove impurities, including water, to meet the specifications of marketable natural gas. The by-products of this processing include: ethane, propane, butanes, pentanes, and higher molecular weight hydrocarbons, hydrogen sulfide (which may be converted into pure sulfur), carbon dioxide, water vapor, and sometimes helium and nitrogen.

Natural gas is often informally referred to simply as "gas", especially when compared to other energy sources such as oil or coal. However, it is not to be confused with gasoline, especially in North America, where the term gasoline is often shortened in colloquial usage to gas.

Period 6 element

A period 6 element is one of the chemical elements in the sixth row (or period) of the periodic table of the elements, including the lanthanides. The periodic table is laid out in rows to illustrate recurring (periodic) trends in the chemical behaviour of the elements as their atomic number increases: a new row is begun when chemical behaviour begins to repeat, meaning that elements with similar behaviour fall into the same vertical columns. The sixth period contains 32 elements, tied for the most with period 7, beginning with caesium and ending with radon. Lead is currently the last stable element; all subsequent elements are radioactive. For bismuth, however, its only primordial isotope, 209Bi, has a half-life of more than 1019 years, over a billion times longer than the current age of the universe. As a rule, period 6 elements fill their 6s shells first, then their 4f, 5d, and 6p shells, in that order; however, there are exceptions, such as gold.


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.


A radionuclide (radioactive nuclide, radioisotope or radioactive isotope) is an atom that has excess nuclear energy, making it unstable. This excess energy can be used in one of three ways: emitted from the nucleus as gamma radiation; transferred to one of its electrons to release it as a conversion electron; or used to create and emit a new particle (alpha particle or beta particle) from the nucleus. During those processes, the radionuclide is said to undergo radioactive decay. These emissions are considered ionizing radiation because they are powerful enough to liberate an electron from another atom. The radioactive decay can produce a stable nuclide or will sometimes produce a new unstable radionuclide which may undergo further decay. Radioactive decay is a random process at the level of single atoms: it is impossible to predict when one particular atom will decay. However, for a collection of atoms of a single element the decay rate, and thus the half-life (t1/2) for that collection can be calculated from their measured decay constants. The range of the half-lives of radioactive atoms have no known limits and span a time range of over 55 orders of magnitude.

Radionuclides occur naturally or are artificially produced in nuclear reactors, cyclotrons, particle accelerators or radionuclide generators. There are about 730 radionuclides with half-lives longer than 60 minutes (see list of nuclides). Thirty-two of those are primordial radionuclides that were created before the earth was formed. At least another 60 radionuclides are detectable in nature, either as daughters of primordial radionuclides or as radionuclides produced through natural production on Earth by cosmic radiation. More than 2400 radionuclides have half-lives less than 60 minutes. Most of those are only produced artificially, and have very short half-lives. For comparison, there are about 252 stable nuclides. (In theory, only 146 of them are stable, and the other 106 are believed to decay (alpha decay or beta decay or double beta decay or electron capture or double electron capture))

All chemical elements can exist as radionuclides. Even the lightest element, hydrogen, has a well-known radionuclide, tritium. Elements heavier than lead, and the elements technetium and promethium, exist only as radionuclides. (In theory, elements heavier than dysprosium exist only as radionuclides, but the half-life for some such elements (e.g. gold and platinum) are too long to found)

Unplanned exposure to radionuclides generally has a harmful effect on living organisms including humans, although low levels of exposure occur naturally without harm. The degree of harm will depend on the nature and extent of the radiation produced, the amount and nature of exposure (close contact, inhalation or ingestion), and the biochemical properties of the element; with increased risk of cancer the most usual consequence. However, radionuclides with suitable properties are used in nuclear medicine for both diagnosis and treatment. An imaging tracer made with radionuclides is called a radioactive tracer. A pharmaceutical drug made with radionuclides is called a radiopharmaceutical.

Wright Haskell Langham

Wright Haskell Langham (21 May 1911 – 19 May 1972) was an internationally renowned expert in the fields of plutonium exposure, aerospace and aviation medicine, Eniwetok nuclear tests, the Palomares and Greenland nuclear accidents. Sometimes Langham was referred to as Mr. Plutonium.

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