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Polonium

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Polonium

Atomic Mass	209
Electron Configuration	[Xe]6s24f145d106p4
Oxidation States	+4, +2
Year Discovered	1898

Polonium

Atomic Mass	209
Electron Configuration	[Xe]6s24f145d106p4
Oxidation States	+4, +2
Year Discovered	1898

Identifiers

Element Name	Polonium
Element Symbol	Po
InChI	InChI=1S/Po
InChIKey	HZEBHPIOVYHPMT-UHFFFAOYSA-N

Properties

Atomic Weight	209 209 [209]
Electron Configuration	[Xe]6s²4f¹⁴5d¹⁰6p⁴
Atomic Radius	Van der Waals Atomic Radius : 197 pm (Van der Waals) Empirical Atomic Radius : 190pm (Empirical) Covalent Atomic Radius : 140(4) pm (Covalent)
Oxidation States	+4, +2 6, 5, 4, 2, -1
Ground Level	³P₂
Ionization Energy	8.417 eV 8.418070 ± 0.000004 eV
Electronegativity	Pauling Scale Electronegativity : 2(Pauling Scale) Allen Scale Electronegativity : 2.19(Allen Scale)
Electron Affinity	1.9eV 1.32eV
Atomic Spectra	Lines Holdings Levels Holdings
Physical Description	Solid
Element Classification	Metal
Element Period Number	6
Element Group Number	16 - Chalcogen
Density	9.32 grams per cubic centimeter
Melting Point	527 K (254°C or 489°F) 254°C
Boiling Point	1235 K (962°C or 1764°F) 962°C
Estimated Crustal Abundance	2×10^-10 milligrams per kilogram
Estimated Oceanic Abundance	1.5×10^-14 milligrams per liter

History

Polonium was discovered by Marie Sklodowska Curie, a Polish chemist, in 1898. She obtained polonium from pitchblende, a material that contains uranium, after noticing that unrefined pitchblende was more radioactive than the uranium that was separated from it. She reasoned that pitchblende must contain at least one other radioactive element. Curie needed to refine several tons of pitchblende in order to obtain tiny amounts of polonium and radium, another radioactive element discovered by Curie. One ton of uranium ore contains only about 100 micrograms (0.0001 grams) of polonium. Due to its scarcity, polonium is usually produced by bombarding bismuth-209 with neutrons in a nuclear reactor. This forms bismuth-210, which has a half-life of 5 days. Bismuth-210 decays into polonium-210 through beta decay. Milligram amounts of polonium-210 have been produced by this method.

Polonium-210 is a very strong emitter of alpha particles. A single gram of polonium-210 creates 140 Watts of heat energy and is being considered as a lightweight heat source for thermoelectric power for spacecraft. Polonium-210 has a half-life of 138.39 days.

Polonium's most stable isotope, polonium-209, has a half-life of 102 years. It decays into lead-205 through alpha decay. Polonium-209 is available from Oak Ridge National Laboratory at the cost of about $3200 per microcurie.

Named after Poland, native country of Madam Curie. Polonium, also called Radium F, was the first element discovered by Curie in 1898 while seeking the cause of radioactivity of pitchblend from Joachimsthal, Bohemia. The electroscope showed it separating with bismuth.

Description

Polonium-210 is a low-melting, fairly volatile metal, 50% of which is vaporized in air in 45 hours at 55°C. It is an alpha emitter with a half-life of 138.39 days. A milligram emits as many alpha particles as 5 g of radium.

The energy released by its decay is so large (140W/g) that a capsule containing about half a gram reaches a temperature above 500C. The capsule also presents a contact gamma-ray dose rate of 0.012 Gy/h. A few curies (1 curie = 3.7 x 10¹⁰Bq) of polonium exhibit a blue glow, caused by excitation of the surrounding gas.

Polonium is readily dissolved in dilute acids, but is only slightly soluble in alkali. Polonium salts of organic acids char rapidly; halide amines are reduced to the metal.

Users

Polonium can be used to eliminate static electricity in machinery that is caused by processes such as the rolling of paper, wire or sheet metal, although other materials which emit beta particles are more commonly used for this purpose. Polonium is also used in brushes for removing dust from photographic films, although the polonium must be carefully sealed to protect the user from contamination. Polonium is also combined with beryllium to form neutron sources.

Because almost all alpha radiation is stopped within the solid source and its container, giving up its energy, polonium has attracted attention for uses as a lightweight heat source for thermoelectric power in space satellites.

Polonium can be mixed or alloyed with beryllium to provide a source of neutrons. The element has been used in devices for eliminating static charges in textile mills, etc.; however, beta sources are both more commonly used and less dangerous. It is also used on brushes for removing dust from photographic films. The polonium for these is carefully sealed and controlled, minimizing hazards to the user.

Sources

Polonium is a very rare natural element. Uranium ores contain only about 100 micrograms of the element per ton. Its abundance is only about 0.2% of that of radium.

In 1934, scientists discovered that when they bombarded natural bismuth (209Bi) with neutrons, 210Bi, the parent of polonium, was obtained. Milligram amounts of polonium may now be prepared this way, by using the high neutron fluxes of nuclear reactors.

Compounds

See more information at the Polonium compound page.

Element Forms

CID	Name	Formula	SMILES	Molecular Weight
6328143	polonium	Po	[Po]	208.98243
6328544	polonium-210	Po	[210Po]	209.98287
6328554	polonium-218	Po	[218Po]	218.00897
6335815	polonium-216	Po	[216Po]	216.00191
6337584	polonium-215	Po	[215Po]	214.99942
6337588	polonium-211	Po	[211Po]	210.98665
24755505	polonium-209	Po	[209Po]	208.98243
6337586	polonium-207	Po	[207Po]	206.98159
24755511	polonium-200	Po	[200Po]	199.98181
24755506	polonium-208	Po	[208Po]	207.98125
24755508	polonium-204	Po	[204Po]	203.9803
24755510	polonium-201	Po	[201Po]	200.98226
6337600	polonium-203	Po	[203Po]	202.98142
6337601	polonium-205	Po	[205Po]	204.9812
24755507	polonium-206	Po	[206Po]	205.98047
24755509	polonium-202	Po	[202Po]	201.98074
24755512	polonium-199	Po	[199Po]	198.98364
24755513	polonium-198	Po	[198Po]	197.9834
24755514	polonium-197	Po	[197Po]	196.9856
24755515	polonium-196	Po	[196Po]	195.98554
24755516	polonium-195	Po	[195Po]	194.98807
24755517	polonium-194	Po	[194Po]	193.9882
24755518	polonium-193	Po	[193Po]	192.9911
24755519	polonium-192	Po	[192Po]	191.9913
24755520	polonium-191	Po	[191Po]	190.99456
24755521	polonium-190	Po	[190Po]	189.9951
24755522	polonium-217	Po	[217Po]	217.00632

Handling And Storage

Polonium-210 is very dangerous to handle in even milligram or microgram amounts, and special equipment and strict control is necessary. Damage arises from the complete absorption of the energy of the alpha particle into tissue.

The maximum permissible body burden for ingested polonium is only 0.03 microcuries, which represents a particle weighing only 6.8 x 10-12 g. Weight for weight it is about 2.5 x 1011 times as toxic as hydrocyanic acid. The maximum allowable concentration for soluble polonium compounds in air is about 2 x 10-11 microcuries/cm3.

Isotopes

Stable Isotope Count	0
Summary	Twenty five isotopes of polonium are known, with atomic masses ranging from 194 to 218. Polonium-210 is the most readily available. Isotopes of mass 209 (half-life 103 years) and mass 208 (half-life 2.9 years) can be prepared by alpha, proton, or deuteron bombardment of lead or bismuth in a cyclotron, but these are expensive to produce.

Isotopes in Industry

210Po (with a half-life of 138 days) is used as static eliminator to remove static electricity in machinery. This is useful in machinery that produces electricity easily, for example, via rolling paper, manufacturing sheet plastics, and spinning synthetic fibers, which all readily produce static [75], [563]. 210Po can also make use of its static eliminating properties when used in brushes that function to clean camera lenses and photographic films (Fig. IUPAC.84.1) [75]. 210Po has been used to manufacture atomic weapons. When combined with beryllium, polonium can act as a neutron-producing initiator. However, because of its short half-life, 210Po is no longer used in this manner [75].

Fig. IUPAC.84.1: Staticmaster™ Alpha Ionizing Brushes for cleaning optical surfaces and photographic films have a soft, non-abrasive brush and a ²¹⁰Po cartridge. (Photo Source: Reston Stable Isotope Laboratory of the U.S. Geological Survey) [564].

[75] J. Peterson, M. McDonell, L. Haroun, F. Monette, R. D. Hildebrand, A. Taboas. Radiological and Chemical Fact Sheets to Support Health Risk Analyses for Contaminated Areas, Prepared by Argonne National Laboratory Environmental Science Division in collaboration with U.S. Department of Energy, Richland Operations Office and Chicago Operations Office (2014), Feb. 22; http://www.remm.nlm.gov/ANL_ContaminantFactSheets_All_070418.pdf.

[563] United States Nuclear Regulatory Commission. Backgrounder on Polonium-210, United States Nuclear Regulatory Commission (2017), April 8; http://www.nrc.gov/reading-rm/doc-collections/fact-sheets/polonium.html.

[564] Reston Stable Isotope Laboratory. Staticmaster™ Alpha Ionizing Brush.

Isotope Mass and Abundance

Isotope	Atomic Mass (uncertainty) [u]	Abundance (uncertainty)
²⁰⁹Po	208.9824308(20)
²¹⁰Po	209.9828741(13)

Atomic Mass, Half Life, and Decay

Nuclide	Atomic Mass and Uncertainty [u]	Half Life and Uncertainty	Discovery Year	Decay Modes, Intensities and Uncertainties [%]
¹⁸⁶Po	186.004403174 ± 0.000019622	34 us ± 12	2005	α≈100%; p ?
¹⁸⁷Po	187.003031482 ± 0.00003503	1.40 ms ± 0.25	2005	α≈100%; β⁺ ?
¹⁸⁷Po^m	187.003031482 ± 0.00003503	0.5 ms	2006	α≈100%; β⁺ ?
¹⁸⁸Po	187.999415586 ± 0.000021438	270 us ± 30	1999	α≈100%; β⁺ ?
¹⁸⁹Po	188.998473425 ± 0.000023681	3.5 ms ± 0.5	1999	α≈100%; β⁺ ?
¹⁹⁰Po	189.995101731 ± 0.000014131	2.45 ms ± 0.05	1996	α=100%; β⁺ ?
¹⁹¹Po	190.994558494 ± 0.000007624	22 ms ± 1	1993	α≈100%; β⁺ ?
¹⁹¹Po^m	190.994558494 ± 0.000007624	93 ms ± 3	1999	α≈100%; β⁺ ?
¹⁹²Po	191.991340274 ± 0.000011416	32.2 ms ± 0.3	1977	α≈100%; β⁺ ?
¹⁹²Po^m	191.991340274 ± 0.000011416	580 ns ± 100	1999	IT=100%
¹⁹³Po	192.991062421 ± 0.000015599	399 ms ± 34	1967	α≈100%; β⁺ ?
¹⁹³Po^m	192.991062421 ± 0.000015599	245 ms ± 11	1981	α≈100%; β⁺ ?
¹⁹⁴Po	193.988186058 ± 0.00001386	392 ms ± 4	1967	α≈100%; β⁺ ?
¹⁹⁴Po^m	193.988186058 ± 0.00001386	12.9 us ± 0.5	1999	IT=100%
¹⁹⁵Po	194.988065781 ± 0.000006486	4.64 s ± 0.09	1967	α=94±0.4%; β⁺ ?
¹⁹⁵Po^m	194.988065781 ± 0.000006486	1.92 s ± 0.02	1967	α≈100%; β⁺ ?; IT ?
¹⁹⁶Po	195.985540722 ± 0.000005778	5.63 s ± 0.07	1967	α=94±0.5%; β⁺ ?
¹⁹⁶Po^m	195.985540722 ± 0.000005778	856 ns ± 17	1995	IT=100%
¹⁹⁷Po	196.985621939 ± 0.000010585	53.6 s ± 0.9	1965	β⁺ ?; α=44±0.7%
¹⁹⁷Po^m	196.985621939 ± 0.000010585	25.8 s ± 0.1	1967	α=84±0.9%; β⁺ ?; IT ?
¹⁹⁸Po	197.983388753 ± 0.000018705	1.760 m ± 0.024	1965	α=57±0.2%; β⁺=43±0.2%
¹⁹⁸Po^m	197.983388753 ± 0.000018705	200 ns ± 20	1990	IT=100%
¹⁹⁸Poⁿ	197.983388753 ± 0.000018705	750 ns ± 50	1990	IT=100%
¹⁹⁹Po	198.983640445 ± 0.000005828	5.47 m ± 0.15	1965	β⁺=92.5±0.3%; α=7.5±0.3%
¹⁹⁹Po^m	198.983640445 ± 0.000005828	4.17 m ± 0.05	1964	β⁺=73.5±1%; α=24±0.1%; IT=2.5±1%
²⁰⁰Po	199.981812355 ± 0.000008136	11.51 m ± 0.08	1951	β⁺=88.9±0.3%; α=11.1±0.3%
²⁰⁰Po^m	199.981812355 ± 0.000008136	100 ns ± 10	1985	IT=100%
²⁰⁰Poⁿ	199.981812355 ± 0.000008136	268 ns ± 3	1985	IT=100%
²⁰¹Po	200.982263799 ± 0.000005305	15.6 m ± 0.1	1951	β⁺=98.87±0.3%; α=1.13±0.3%
²⁰¹Po^m	200.982263799 ± 0.000005305	8.96 m ± 0.12	1962	IT=56.2±1.2%; β⁺=41.4±0.7%; α=2.4±0.5%
²⁰²Po	201.980738934 ± 0.000009307	44.6 m ± 0.4	1951	β⁺=98.08±0.7%; α=1.92±0.7%
²⁰²Po^m	201.980738934 ± 0.000009307	110 ns ± 15	1971	IT=100%
²⁰³Po	202.981416072 ± 0.000004981	36.7 m ± 0.5	1951	β⁺=99.89±0.2%; α=0.11±0.2%
²⁰³Po^m	202.981416072 ± 0.000004981	45 s ± 2	1969	IT≈100%; α ?
²⁰³Poⁿ	202.981416072 ± 0.000004981	>200 ns	1986	IT=100%
²⁰⁴Po	203.980310078 ± 0.000010811	3.519 h ± 0.012	1951	β⁺=99.33±0.3%; α=0.67±0.3%
²⁰⁴Po^m	203.980310078 ± 0.000010811	158.6 ns ± 1.8	1970	IT=100%
²⁰⁵Po	204.981190006 ± 0.000010798	1.74 h ± 0.08	1951	β⁺=99.960±1.2%; α=0.040±1.2%
²⁰⁵Po^m	204.981190006 ± 0.000010798	310 ns ± 60	1960	IT=100%
²⁰⁵Poⁿ	204.981190006 ± 0.000010798	645 us ± 20	1962	IT=100%
²⁰⁵Po^p	204.981190006 ± 0.000010798	57.4 ms ± 0.9	1973	IT=100%
²⁰⁵Po^q	204.981190006 ± 0.000010798	115 ns ± 10	1985	IT=100%
²⁰⁶Po	205.980473662 ± 0.000004306	8.8 d ± 0.1	1947	β⁺=94.55±0.5%; α=5.45±0.5%
²⁰⁶Po^m	205.980473662 ± 0.000004306	232 ns ± 4	1970	IT=100%
²⁰⁶Poⁿ	205.980473662 ± 0.000004306	1.05 us ± 0.06	1970	IT=100%
²⁰⁷Po	206.981593334 ± 0.000007148	5.80 h ± 0.02	1947	β⁺≈100%; α=0.021±0.2%
²⁰⁷Po^m	206.981593334 ± 0.000007148	205 ns ± 10	1963	IT=100%
²⁰⁷Poⁿ	206.981593334 ± 0.000007148	49 us ± 4	1962	IT=100%
²⁰⁷Po^p	206.981593334 ± 0.000007148	2.79 s ± 0.08	1961	IT=100%
²⁰⁸Po	207.981246035 ± 0.000001795	2.898 y ± 0.002	1947	α≈100%; β⁺=0.0042±0.4%
²⁰⁸Po^m	207.981246035 ± 0.000001795	373 ns ± 8	1968	IT=100%
²⁰⁹Po	208.982430361 ± 0.000001909	124 y ± 3	1949	α=99.546±0.7%; β⁺=0.454±0.7%
²⁰⁹Po^m	208.982430361 ± 0.000001909	119 ns ± 4	1974	IT=100%
²¹⁰Po	209.982873686 ± 0.00000123	138.376 d ± 0.002	1898	α=100%
²¹⁰Po^m	209.982873686 ± 0.00000123	98.9 ns ± 2.5	1968	IT=100%
²¹⁰Poⁿ	209.982873686 ± 0.00000123	263 ns ± 5	1985	IT=100%
²¹¹Po	210.986653171 ± 0.000001347	516 ms ± 3	1913	α=100%
²¹¹Po^m	210.986653171 ± 0.000001347	25.2 s ± 0.6	1954	α=99.984±0.4%; IT=0.016±0.4%
²¹¹Poⁿ	210.986653171 ± 0.000001347	243 ns ± 21	1998	IT≈100%; α ?
²¹¹Po^p	210.986653171 ± 0.000001347	2.8 us ± 0.7	1998	IT≈100%; α ?
²¹²Po	211.988867982 ± 0.000001237	294.4 ns ± 0.8	1906	α=100%
²¹²Po^m	211.988867982 ± 0.000001237	45.1 s ± 0.6	1962	α=99.93±0.2%; IT ?
²¹³Po	212.992857154 ± 0.000003277	3.705 us ± 0.001	1947	α=100%
²¹⁴Po	213.995201287 ± 0.000001556	163.47 us ± 0.03	1912	α=100%
²¹⁵Po	214.999418385 ± 0.000002276	1.781 ms ± 0.005	1911	α=100%; β^-=2.3e-4±0.2%
²¹⁶Po	216.001913416 ± 0.000001948	144.0 ms ± 0.6	1910	α=100%; 2β^- ?
²¹⁷Po	217.006316145 ± 0.000007025	1.53 s ± 0.05	1956	α=97.5±1.4%; β^-=2.5±1.4%
²¹⁸Po	218.008971234 ± 0.000002112	3.097 m ± 0.012	1904	α=99.980±0.2%; β^-=0.020±0.2%
²¹⁹Po	219.013614000 ± 0.000017	10.3 m ± 1.0	1998	β^-=71.8±2%; α=28.2±2%
²²⁰Po	220.016386000 ± 0.000019	10 s >300ns [Estimated]	1998	β^- ?
²²¹Po	221.021228000 ± 0.000021	2.2 m ± 0.7	2010	β^-=100%
²²²Po	222.024140000 ± 0.000043	9.1 m ± 7.2	2010	β^-=100%
²²³Po	223.029070 ± 0.00021 [Estimated]	6 s >300ns [Estimated]	2010	β^- ?
²²⁴Po	224.032110 ± 0.00021 [Estimated]	3 m >300ns [Estimated]	2010	β^- ?
²²⁵Po	225.037123 ± 0.000322 [Estimated]	10 s >300ns [Estimated]	2010	β^- ?
²²⁶Po	226.040310 ± 0.00043 [Estimated]	1 m >300ns [Estimated]	2010	β^- ?
²²⁷Po	227.045390 ± 0.00043 [Estimated]	2 s >300ns [Estimated]	2010	β^- ?

Information Sources

1. PubChem

https://pubchem.ncbi.nlm.nih.gov
2. Atomic Mass Data Center (AMDC), International Atomic Energy Agency (IAEA)

LICENSE
https://www-nds.iaea.org/disclaimer.html

Po
https://www-nds.iaea.org/amdc/
3. IUPAC Commission on Isotopic Abundances and Atomic Weights (CIAAW)

LICENSE
http://www.ciaaw.org/bylaws.htm

Polonium
https://www.ciaaw.org/
4. IUPAC Periodic Table of the Elements and Isotopes (IPTEI)

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Copyright (c) 2020 International Union of Pure and Applied Chemistry. The International Union of Pure and Applied Chemistry (IUPAC) contribution within Pubchem is provided under a CC-BY-NC-ND 4.0 license, unless otherwise stated.
https://creativecommons.org/licenses/by-nc-nd/4.0/

https://doi.org/10.1515/pac-2015-0703
5. Jefferson Lab, U.S. Department of Energy

LICENSE
Please see citation and linking information https https://www.jlab.org/privacy-and-security-notice

Polonium
https://education.jlab.org/itselemental/ele084.html
6. Los Alamos National Laboratory, U.S. Department of Energy

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https://about.lanl.gov/lanl-resources/web-policies/

Polonium
https://periodic.lanl.gov/84.shtml
7. NIST Physical Measurement Laboratory

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https://www.nist.gov/pml/database-disclaimer

Polonium
https://physics.nist.gov/cgi-bin/Elements/elInfo.pl?element=84
8. PubChem Elements

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https://www.nlm.nih.gov/copyright.html

Polonium

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