<table border="1" cellpadding="2" cellspacing="0" align="right">
<tr><td colspan="2" cellspacing="0" cellpadding="2">
<table align="center" border="0">
<tr><td colspan="2" align="center">Bi - '''Po''' - At</td>
</tr>
<tr><td rowspan="3" valign="center">Te<br />'''Po'''<br /> &nbsp;</td></tr>
<tr><td align="center">250px<br />
<div style="text-align: center">Układ okresowy</div></td></tr>
</table>
</td></tr>
<tr>
<th colspan="2" align=center bgcolor="#cccc99"><font color="black">'''Dane ogólne'''</font></th></tr>
<tr>
<td>Nazwa, symbol, l.a.*</td><td>Polon, Po, 84</td></tr>
<tr>
<td>Własności metaliczne</td><td>metaloid</td></tr>
<tr>
<td>Grupa, okres, blok</td><td>16 (VIA), 6, p</td></tr>
<tr>
<td>twardość</td><td>9196 kg/m<sup>3</sup>, bd</td></tr>
<tr>
<td>Kolor</td><td>srebrzystoszary</td></tr>
<tr>
<th colspan="2" align="center" bgcolor="#cccc99"><font color="black">'''Własności atomowe'''</font></th></tr>
<tr>
<td>u</td></tr>
<tr>
<td>pm</td></tr>
<tr>
<td>Promień kowalencyjny</td><td>bd</td></tr>
<tr>
<td>Promień van der Waalsa</td><td>bd</td></tr>
<tr>
<td>Xe<nowiki>]</nowiki>4f<sup>14</sup>5d<sup>10</sup>6s²6p<sup>4</sup></td></tr>
<tr>
<td>e<sup>-</sup> na poziom energetyczny</td><td>2, 8, 18, 32, 18, 6</td></tr>
<tr>
<td>Stopień utlenienia</td><td>'''4''', 2</td></tr>
<tr>
<td>Własności kwasowe tlenków</td><td>amfoteryczne</td></tr>
<tr>
<td>Struktura krystaliczna</td><td>jednoskośna</td></tr>
<tr>
<th colspan="2" align="center" bgcolor="#cccc99"><font color="black">'''Własności fizyczne'''</font></th></tr>
<tr><td>Stan skupienia</td><td>stały</td></tr>
<tr>
<td>K (254 °C)</td></tr>
<tr>
<td>Temperatura wrzenia</td><td>1235 K (962°C)</td></tr>
<tr>
<td>Objętość molowa</td><td>21,97×10<sup>-6</sup> m³/mol</td></tr>
<tr>
<td>kJ/mol</td></tr>
<tr>
<td>Ciepło topnienia</td><td>10 kJ/mol</td></tr>
<tr>
<td>Pa (527 K)</td></tr>
<tr>
<td>Prędkość dźwięku</td><td>bd</td></tr>
<tr>
<th colspan="2" align="center" bgcolor="#cccc99"><font color="black">'''Pozostałe dane'''</font></th></tr>
<tr>
<td>Pauling)<br />1,76 (Allred)</td></tr>
<tr>
<td>J/(kg*K)</td></tr>
<tr>
<td>Przewodność właściwa</td><td>2,19×10<sup>6</sup> S/m</td></tr>
<tr>
<td>W/(m*K)</td></tr>
<tr>
<td>I Potencjał jonizacyjny</td><td>812,1 kJ/mol</td></tr>
<tr>
<td>II Potencjał jonizacyjny</td><td>1800 kJ/mol</td></tr>
<tr>
<td>III Potencjał jonizacyjny</td><td>2700 kJ/mol</td></tr>
<tr>
<td>IV Potencjał jonizacyjny</td><td>3700 kJ/mol</td></tr>
<th colspan="2" align="center" bgcolor="#cccc99"><font color="black">'''Najbardziej stabilne izotopy*'''</font></th></tr>
<tr>
<td colspan="2">
<table border="1" cellspacing="0" cellpadding="2" width="100%">
<tr>
<th>o.p.r.</th><th>s.r.</th><th>e.r. MeV</th><th>p.r.</th>
</tr><tr>
<td><sup>206</sup>Po</td>
<td>{syn.}</td>
<td>8,3 dni</td>
<td>w.e.</td>
<td>&nbsp;</td>
<td><sup>206</sup>Bi</td>
</tr><tr>
<td rowspan="2"><sup>208</sup>Po</td>
<td rowspan="2">{syn.}</td>
<td rowspan="2">2,898 lat</td>
<td>w.e.</td>
<td>1,401</td>
<td><sup>208</sup>Bi</td>
</tr><tr>
<td>α</td>
<td>5,215</td>
<td><sup>204</sup>Pb</td>
</tr><tr>
<td rowspan="2"><sup>209</sup>Po</td>
<td rowspan="2">{syn.}</td>
<td rowspan="2">103 lat</td>
<td>w.e.</td>
<td>1,893</td>
<td><sup>209</sup>Bi</td>
</tr><tr>
<td>α</td>
<td>4,979</td>
<td><sup>205</sup>Pb</td>
</tr><tr>
<td><sup>210</sup>Po</td>
<td>{syn.}</td>
<td>138,376 dni</td>
<td>α</td>
<td>5,407</td>
<td><sup>206</sup>Pb</td>
</tr>
</table></td></tr>
<th colspan="2" align="center" bgcolor="#cccc99">
<font size="-1">Tam, gdzie nie jest zaznaczone inaczej,<br />użyte są jednostki SI i warunki normalne.
</font></th>
</tr>
<tr>
<td colspan=2><font size=-1>*Wyjaśnienie skrótów:<br />l.a.=liczba atomowa<br />wyst.=występowanie w przyrodzie,<br />o.p.r.=okres połowicznego rozpadu,<br />s.r.=sposób rozpadu,<br />e.r.=energia rozpadu,<br />p.r.=produkt rozpadu,<br />w.e.=wychwyt elektronu
</font></td></tr>
</table>
'''Polon''' ('''Po''', metaloidów bloku p w układzie okresowym. Nazwa pochodzi od łacińskiej nazwy Polski.

Występowanie: polon występuje w skorupie ziemskiej w śladowych ilościach w rudach uranu.

Posiada 33 izotopy z przedziału mas 194-218. Nie posiada trwałych izotopów.
Względnie najtrwalszy jest izotop 209 (okres połowicznego rozpadu 103 lat), paradoksalnie nie występuje on jednak naturalnie, lecz został otrzymany w wyniku sztucznej syntezy jądrowej poprzez bombardowanie bizmutu neutronami. Najtrwalszym, naturalnie występującym izotopem jest izotop 210, który ma czas połowicznego rozpadu 138 dni.

Pierwiastek ten został odkryty w Marię Skłodowską-Curie i Piotra Curie - w tym samym roku co rad.

Polon występuje naturalnie w złożach rud uranu, jako tlenek. Jego stężenie w tych rudach jest jednak tak małe, że przemysłowo opłaca się go otrzymywać na drodze wcześniej wspomnianego bombardowania bizmutu neutronami. Jego światowa produkcja wynosi ok. 100 gramów rocznie <ref>http://www.rsc.org/chemistryworld/News/2006/November/27110601.asp RSC Chemistry World Q&A</ref>. Ilość polonu w skorupie ziemskiej jest na tyle mała, że nie podaje się żadnych, nawet szacunkowych danych na ten temat.

Znanych jest kilkanaście związków chemicznych polonu: tlenek PoO<sub>2</sub>, wodorotlenek Po(OH)<sub>2</sub>, halogenki, np. PoCl<sub>2</sub>, PoBr<sub>4</sub>, siarczek PoS i ZSRR jako aktywator lakierów luminescencyjnych stosowanych w lampach, obecnie został już jednak zastąpiony tańszymi zamiennikami.

Czysty polon jest silnie radioaktywnym, srebrzystoszarym metalem. Jego własności fizyczne i chemiczne zbliżone są do cząstek alfa.

Polon wprowadzony do organizmu jest silnie toksyczny. Duże stężenie polonu 210 stwierdzono w organizmie Aleksandra Litwinienko, otrutego w listopadzie 2006 roku w Londynie.

== Źródła ==
<div class="references-small"><references /></div>

'''Polonium''' () is a chemical element that has the symbol '''Po''' and atomic number 84. A rare and highly radioactive metalloid,<ref>[http://www.chemicalelements.com/groups/metalloids.html Chemical Elements.com - Metalloids<!-- Bot generated title -->]</ref> polonium is chemically similar to bismuth<ref>[http://hyperphysics.phy-astr.gsu.edu/hbase/pertab/Po.html]</ref> and tellurium , and it occurs in uranium ores. Polonium has been studied for possible use in heating spacecraft.  It is unstable; all isotopes of polonium are radioactive. 

===Characteristics===
Polonium is a radioactive element that exists in two metallic allotropes.<ref></ref>

=== Isotopes ===

Polonium has 25 known isotopes, all of which are radioactive.  They have atomic masses that range from 194u to 218u. <sup>210</sup>Po (half-life 138.376 days) is the most widely available. <sup>209</sup>Po (half-life 103 years) and <sup>208</sup>Po (half-life 2.9 years) can be made through the alpha, proton, or deuteron bombardment of lead or bismuth in a cyclotron.

;'''<sup>210</sup>Po'''
<sup>210</sup>Po is an alpha emitter that has a half-life of 138.376 days; it decays directly to its daughter isotope <sup>206</sup>Pb.  A milligram of <sup>210</sup>Po emits about as many alpha particles per second as 4.5 grams of <sup>226</sup>Ra. A few gigabecquerels) of <sup>210</sup>Po emit a blue glow which is caused by excitation of surrounding air. A single gram of <sup>210</sup>Po generates 140 watts of power.<ref>[http://www.ead.anl.gov/pub/doc/polonium.pdf Polonium], Argonne National Laboratory</ref> Because it emits many alpha particles, which are stopped within a very short distance in dense media and release their energy, <sup>210</sup>Po has been used as a lightweight heat source to power thermoelectric cells in artificial satellites; for instance,  <sup>210</sup>Po heat source was also used in each of the Lunokhod rovers deployed on the surface of the Moon, to keep their internal components warm during the lunar nights.<ref>Andrew Wilson, ''Solar System Log'', (London:  Jane's Publishing Company Ltd, 1987), p. 64.</ref>  Some anti-static brushes contain up to 500 microcuries of <sup>210</sup>Po as a source of charged particles for neutralizing static electricity in materials like photographic film.<ref>[http://www.amstat.com/solutions/staticmaster.html Staticmaster<!-- Bot generated title -->]</ref>   <sup>210</sup>Po was also used as a murder weapon in the Alexander Litvinenko poisoning

The majority of the time <sup>210</sup>Po decays by emission of an alpha particle only, not by emission of an alpha particle and a gamma ray. About one in 100,000 alpha emissions causes an excitation in the nucleus which then results in the emission of a gamma ray.<ref>[http://atom.kaeri.re.kr/cgi-bin/decay?Po-210%20A 210PO a decay<!-- Bot generated title -->]</ref> This low gamma ray production rate (and the short range of alpha particles) makes it difficult to find and identify this isotope. Rather than gamma ray spectroscopy, alpha spectroscopy is the best method of measuring this isotope.
<!-- PLEASE DO NOT ADD        L I T V I N E N K O        HERE!

He is already mentioned below in the "Famous polonium poisoning cases" section -->

=== Solid state form ===
The alpha form of solid polonium has a simple cubic crystal structure with an edge length of 3.352 Å.

The beta form of polonium is rhombohedral; it has been reported in the chemical literature, along with the alpha form, several times. A picture of it is present on the web.<ref>[http://cst-www.nrl.navy.mil/lattice/struk/a_i.html The beta Po (A_i) Structure<!-- Bot generated title -->]</ref>

Two papers report X-ray diffraction experiments on polonium metal.<ref>R.J. Desando and R.C Lange, ''Journal of Inorganic and Nuclear Chemistry'', 1966, '''28''', 1837-1846.</ref><ref>W.H Beamer and C.R. Maxwell, ''Journal of Chemical Physics'', 1946, '''14''', 569-569.</ref>  The first report of the crystal structure of polonium was done using electron diffraction.<ref>M.A. Rollier, S.B. Hendricks and L.R. Maxwell, ''Journal of Chemical Physics'', 1936, '''4''', 648-652.</ref>

=== Chemistry ===
The chemistry of polonium is similar to that of soluble in M.P. -36.1°C to B.P. 35.3°C). Halides of the structure PoX<sub>2</sub>, PoX<sub>4</sub> and PoX<sub>6</sub> are known. The two oxides PoO<sub>2</sub> and PoO<sub>3</sub> are the products of oxidation of polonium.<ref>Holleman, A. F.; Wiberg, E. "Inorganic Chemistry" Academic Press: San Diego, 2001. ISBN 0-12-352651-5.</ref>

<sup>210</sup>Po (in common with <sup>238</sup>Pu) has the ability to become airborne with ease: if a sample is heated in air to 328&nbsp;K (55°C, 131°F), 50% of it is vaporized in 45 hours, even though the melting point of polonium is 527&nbsp;K (254°C, 489°F) and its boiling point is 1235&nbsp;K (962°C, 1763°F).<ref>{{cite journal
| author = Bogdan Wąs, Ryszard Misiak, Mirosław Bartyzel, Barbara Petelenz 
| title = Thermochromatographic Separation of  <sup>206</sup>,<sup>208</sup>Po from a Bismuth Target Bombardet with Protons
| journal =Nukleonica
| year =2006
| volume =51
| issue = Suppl. 2
| pages = s3-s5
| url =http://www.ichtj.waw.pl/ichtj/nukleon/back/full/vol51_2006/v51s2p03f.pdf
}}</ref>
More than one hypothesis exists for how polonium does this; one suggestion is that small clusters of polonium atoms are spalled off by the alpha decay.

It has been reported that some microbes can methylate polonium by the action of methylcobalamin.<ref>
{{cite journal
| author = Momoshima N.,  Song L.X.,  Osaki S.,Maeda Y., 
| title = Formation and emission of volatile polonium compound by microbial activity and polonium methylation with methylcobalamin.
| journal =Environ Sci Technol
| year =2001
| volume =35
| issue = 15 
| pages = 2956–2960
| url =http://www.medscape.com/medline/abstract/11478248?prt=true
| doi = 10.1021/es001730  S0013-936X(00)01730-2}}
</ref><ref>
{{cite journal
| author = Momoshima N.,  Song L.X., Osaki S.,Maeda Y., 
| title = Biologically induced Po emission from fresh water
| journal =J Environ Radioact.
| year = 2002
| volume = 63
| issue = 2 
| pages = 187–197
| doi =10.1016/S0265-931X(02)00028-0}}</ref>This is similar to the way in which mercury, selenium and tellurium are methylated in living things to create organometallic compounds. As a result when considering the biochemistry of polonium one should consider the possibility that the polonium will follow the same biochemical pathways as selenium and tellurium.

thumb|right|The alpha form of solid polonium.

==Compounds==

== History ==  	 
Also tentatively called "Radium F", polonium was discovered by Marie Skłodowska-Curie and her husband Pierre Curie in 1898<ref></ref> and was later named after Marie Curie's native land of Poland (Latin: ''Polonia''), and not for the Hamlet character, Polonius.<ref>{{cite journal 
| title = Borders of the Nuclear World --- 100 Years After Discovery of Polonium 
| author = Pfützner M.
| journal = Acta Physica Polonica B
| volume = 30
| year = 1999
| pages = 1197
| url =http://adsabs.harvard.edu/abs/1999AcPPB..30.1197P 
| issue = 5}}</ref><ref>{{cite journal 
| title = The centennial of the 1903 Nobel Prize for physics
| author = Adloff J. P.
| journal = Radichimica Acta
| volume = 91
| year = 681-688
| pages = 2003
| doi = 10.1524/ract.91.12.681.23428 
| issue = 12}}</ref> 
Poland at the time was under Russian, Prussian, and Austrian partition, and did not exist as an independent country. It was Curie's hope that naming the element after her native land would publicize its lack of independence. Polonium may be the first element named to highlight a political controversy.<ref>{{cite journal 
| title = Chemical and Polish aspects of polonium and radium discovery
| author = Kabzinska K.
| journal = Przemysl Chemiczny
| volume = 77
| year = 1998
| pages = 104–107 
| issue = 3}}</ref>

This element was the first one discovered by the Curies while they were investigating the cause of pitchblende radioactivity. The pitchblende, after removal of the radioactive elements uranium and thorium, was more radioactive than both the uranium and thorium put together. This spurred the Curies on to find additional radioactive elements. The Curies first separated out polonium from the pitchblende, and then within a few years, also isolated radium.

== Detection ==
thumb|left|Intensity against photon energy for three isotopes.

===Gamma counting===
By means of radiometric methods such as activity measurement with a non-energy-dispersive counter), it is possible to measure the concentrations of <sup>40</sup>K present in all tissues/body fluids as a check of the equipment and as an internal standard.

thumb|right|Intensity against alpha energy for four isotopes, note that the line width is narrow and the fine details can be seen.

thumb|right|Intensity against alpha energy for four isotopes, note that the line width is wide and some of the fine details can not be seen. This is for liquid scintillation counting where random effects cause a variation in the number of visible photons generated per alpha decay.

===Alpha counting===
The best way to test for (and measure) many alpha emitters is to use alpha-particle spectroscopy as it is common to place a drop of the test solution on a metal disk which is then dried out to give a uniform coating on the disk. This is then used as the test sample. If the thickness of the layer formed on the disk is too thick then the lines of the spectrum are broadened, this is because some of the energy of the alpha particles is lost during their movement through the layer of active material. An alternative method is to use internal liquid scintillation where the sample is mixed with a scintillation cocktail. When the light emitted is then counted, some machines will record the amount of light energy per radioactive decay event. Due to the imperfections of the liquid scintillation method (such as a failure for all the photons to be detected, cloudy or coloured samples can be difficult to count) and the fact that random quenching can reduce the number of photons generated per radioactive decay it is possible to get a broadening of the alpha spectra obtained through liquid scintillation. It is likely that these liquid scintillation spectra will be subject to a Gaussian broadening rather than the distortion exhibited when the layer of  active material on a disk is too thick.

A third energy dispersive method for counting alpha particles is to use a semiconductor detector.

From left to right the peaks are due to <sup>209</sup>Po, <sup>210</sup>Po, <sup>239</sup>Pu and <sup>241</sup>Am. The fact that isotopes such as <sup>239</sup>Pu and <sup>241</sup>Am have more than one alpha line indicates that the nucleus has the ability to be in different discrete energy levels (like a molecule can).

== Occurrence and production ==
Polonium is a very rare element in nature because of the short half-life of all its isotopes. It is found in uranium ores at about 100 micrograms per metric ton (1 part in 10<sup>10</sup>), which is approximately 0.2% of the abundance of radium. The amounts in the Earth's crust are not harmful.  Polonium has been found in tobacco smoke from tobacco leaves grown with phosphate fertilizers.<ref></ref><ref>[http://kidslink.bo.cnr.it/besta/fumo/epolonio.html Alpha Radioactivity (210 Polonium) and Tobacco Smoke]</ref>

===Neutron capture===
; Synthesis by (n,<math>\gamma</math>) reaction

In <sup>209</sup>Bi is bombarded with neutrons, <sup>210</sup>Bi is created, which then decays to <sup>210</sup>Po via β decay. The final purification is done pyrochemically followed by liquid-liquid extraction techniques.<ref>http://pubs.acs.org/cgi-bin/archive.cgi/iepdaw/1969/8/i04/pdf/i260032a013.pdf</ref><ref>http://www.freepatentsonline.com/3463739.pdf</ref> Polonium may now be made in milligram amounts in this procedure which uses high neutron fluxes found in nuclear reactors. Only about 100 grams are produced each year, practically all of it in Russia, making polonium exceedingly rare.<ref>http://www.rsc.org/chemistryworld/News/2006/November/27110601.asp RSC Chemistry World Q&A</ref> <ref>[http://www.sptimesrussia.com/index.php?action_id=2&story_id=20100 The St. Petersburg Times - News - Most Polonium Made Near the Volga River<!-- Bot generated title -->]</ref>

=== Proton capture ===
;Synthesis by (p, n) and (p,2n) reactions

It has been found that the longer-lived isotopes of polonium can be formed by proton bombardment of bismuth using a cyclotron. Other more neutron rich isotopes can be formed by the irradiation of platinum with carbon nuclei.<ref></ref>