View source for Thallium

{{Elementbox_header | number=81 | symbol=Tl | name=thallium | left=[[mercury (element)|mercury]] | right=[[lead]] | above=[[indium|In]] | below=[[ununtrium|Uut]] | color1=#cccccc | color2=black }}
{{Elementbox_series | [[poor metal]]s }}
{{Elementbox_groupperiodblock | group=13 | period=6 | block=p }}
{{Elementbox_appearance_img | Tl,81| silvery white }}
{{Elementbox_atomicmass_gpm | [[1 E-25 kg|204.3833]][[List of elements by atomic mass|(2)]] }}
{{Elementbox_econfig | &#91;[[xenon|Xe]]&#93; 4f<sup>14</sup> 5d<sup>10</sup> 6s<sup>2</sup> 6p<sup>1</sup> }}
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{{Elementbox_section_physicalprop | color1=#cccccc | color2=black }}
{{Elementbox_phase | [[solid]] }}
{{Elementbox_density_gpcm3nrt | 11.85 }}
{{Elementbox_densityliq_gpcm3mp | 11.22 }}
{{Elementbox_meltingpoint | k=577 | c=304 | f=579 }}
{{Elementbox_boilingpoint | k=1746 | c=1473 | f=2683 }}
{{Elementbox_heatfusion_kjpmol | 4.14 }}
{{Elementbox_heatvaporiz_kjpmol | 165 }}
{{Elementbox_heatcapacity_jpmolkat25 | 26.32 }}
{{Elementbox_vaporpressure_katpa | 882 | 977 | 1097 | 1252 | 1461 | 1758 | comment= }}
{{Elementbox_section_atomicprop | color1=#cccccc | color2=black }}
{{Elementbox_crystalstruct | hexagonal }}
{{Elementbox_oxistates | 3, '''1'''<br />(mildly [[base (chemistry)|basic]] oxide) }}
{{Elementbox_electroneg_pauling | 1.62 }}
{{Elementbox_ionizationenergies3 | 589.4 | 1971 | 2878 }}
{{Elementbox_atomicradius_pm | [[1 E-10 m|190]] }}
{{Elementbox_atomicradiuscalc_pm | [[1 E-10 m|156]] }}
{{Elementbox_covalentradius_pm | [[1 E-10 m|148]] }}
{{Elementbox_vanderwaalsrad_pm | [[1 E-10 m|196]] }}
{{Elementbox_section_miscellaneous | color1=#cccccc | color2=black }}
{{Elementbox_magnetic | ??? }}
{{Elementbox_eresist_ohmmat20 | 0.18 µ}}
{{Elementbox_thermalcond_wpmkat300k | 46.1 }}
{{Elementbox_thermalexpansion_umpmkat25 | 29.9 }}
{{Elementbox_speedofsound_rodmpsat20 | 818 }}
{{Elementbox_youngsmodulus_gpa | 8 }}
{{Elementbox_shearmodulus_gpa | 2.8 }}
{{Elementbox_bulkmodulus_gpa | 43 }}
{{Elementbox_poissonratio | 0.45 }}
{{Elementbox_mohshardness | 1.2 }}
{{Elementbox_brinellhardness_mpa | 26.4 }}
{{Elementbox_cas_number | 7440-28-0 }}
{{Elementbox_isotopes_begin | color1=#cccccc | color2=black }}
{{Elementbox_isotopes_stable | mn=203 | sym=Tl | na=29.524% | n=122 }}
{{Elementbox_isotopes_decay2 | mn=204 | sym=Tl
 | na=[[synthetic radioisotope|syn]] | hl=119 Ms<br />(3.78 [[year|y]])
 | dm1=[[beta emission|β<sup>-</sup>]] | de1=0.764 | pn1=204 | ps1=[[lead|Pb]]
 | dm2=[[electron capture|ε]] | de2=0.347 | pn2=204 | ps2=[[mercury (element)|Hg]] }}
{{Elementbox_isotopes_stable | mn=205 | sym=Tl | na=70.476% | n=124 }}
{{Elementbox_isotopes_end}}
{{Elementbox_footer | color1=#cccccc | color2=black }}

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==Overview==

[[Image:Thallium.jpg|thumb|left|150px|1 gram of Thallium]]
'''Thallium''' ({{pronEng|ˈθæliəm}}) is a [[chemical element]] with the symbol '''Tl''' and [[atomic number]] 81.<ref>[http://periodic.lanl.gov/elements/81.html ''thallium''], Los Alamos National Laboratory.  Retrieved November 21, 2006.</ref>  This soft gray malleable [[poor metal]] resembles [[tin]] but discolors when exposed to air. Thallium is highly [[toxic]] and is used in rat poisons and insecticides but since it might also cause [[cancer]] (although the United States EPA does not class it as carcinogen), this use has been cut back or eliminated in many countries. It is also used in infrared detectors.<Ref>
{{cite web
| url = http://adsabs.harvard.edu/abs/1977ApOpt..16.2942N
| title = Thallium selenide infrared detector
| accessdate = 2006-11-25
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| author = Nayer, P. S
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| authorlink = 
| coauthors = Hamilton, O.
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| publisher = Smithsonian/NASA ADS Physics Abstract Service
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It has even been used in some murders, earning the nicknames "The Poisoner's Poison" and "Inheritance powder" (alongside [[arsenic]]).

== Notable characteristics ==
This metal is very soft and malleable and can be cut with a knife. 

When it is first exposed to air, thallium has a metallic luster but quickly tarnishes with a bluish-gray tinge that resembles [[lead]] (it is preserved by keeping it under oil). 

A heavy layer of [[oxide]] builds up on thallium if left in air.  

In the presence of water, thallium [[hydroxide]] is formed.

== Applications ==
The odorless and tasteless thallium sulfate was widely used in the past as a rat poison and ant killer. In the United States and many other countries this use is no longer allowed due to safety concerns. Other uses:
*used in the treatment of [[ringworm]] and other [[skin infection]]s. However this use has been limited due to the narrow margin that exists between toxicity and therapeutic benefit.
*[[radioactive]] thallium-201 (half-life of 73 hours) is used for diagnostic purposes in [[nuclear medicine]], particularly in stress tests used for risk stratification in patients with [[coronary artery disease]]   A(CAD).<ref>[http://www.wramc.amedd.army.mil/departments/nuclear/PatientInfo/Thallium.htm Thallium Test] from [[Walter Reed Army Medical Center]]</ref><ref>[http://www.americanheart.org/presenter.jhtml?identifier=4743 Thallium Stress Test] from the [[American Heart Association]]</ref> This isotope of thallium can be generated using a transportable generator which is similar to the [[Technetium-99m generator|technetium cow]].<ref>[http://www.medscape.com/medline/abstract/7169272 Abstract]<!-- dead link --></ref> The generator contains [[lead]]-201 (half life 9.33 hours) which decays by [[electron capture]] to the thallium-201. The lead-201 can be produced in a cyclotron by the bombardment of thallium with [[proton]]s or [[deuteron]]s by the (p,3n) and (d,4n) reactions.<ref>[http://www.med.harvard.edu/JPNM/physics/isotopes/Tl/Tl201/prod.html Thallium-201 production] from Harvard Medical School's Joint Program in Nuclear Medicine</ref>

== Isotopes ==
Thallium has 25 [[isotope]]s which have [[atomic mass]]es that range from 184 to 210. <sup>203</sup>Tl and <sup>205</sup>Tl are the only stable isotopes, and <sup>204</sup>Tl is the most stable [[radioisotope]], with a [[half-life]] of 3.78 years.

Thallium-202 (half life 12.23 days) can be made in a cyclotron<ref>[http://www.eh.doe.gov/ohre/roadmap/histories/0472/0472d.html Thallium Research] from Department of Energy</ref>, while thallium-204 (half life 3.78 years) is made by the neutron activation of stable thallium in a nuclear reactor.<ref>[http://www-pub.iaea.org/MTCD/publications/PDF/te_1340_web.pdf Manual for reactor produced radioisotopes] from the International Atomic Energy Agency</ref>

== Toxicity ==
Thallium and its compounds are very toxic, and should be handled with great care. Contact with skin is dangerous, and adequate ventilation should be provided when melting this metal. Thallium(I) compounds have a high aqueous [[solubility]] and are readily absorbed through the skin. Exposure to them should not exceed 0.1 [[milligram|mg]] per m² of skin in an 8-hour time-weighted average (40-hour work week). Thallium is a suspected human [[carcinogen]]. 

Part of the reason for thallium's high toxicity is that, when present in aqueous solution as the univalent thallium(I) ion (Tl<sup>+</sup>), it exhibits some similarities with essential [[alkali metal]] cations, particularly [[potassium]] (as the atomic radius is almost identical). It can thus enter the body via potassium uptake pathways. However, other aspects of thallium's chemistry are very different from that of the alkali metals  (''e.g.'', its high affinity for [[sulfur]] ligands due to the presence of empty d-orbitals), and so this substitution disrupts many cellular processes (for instance, thallium may attack sulphur-containing proteins such as [[cysteine]] residues and [[ferredoxin]]s).

Thallium's toxicity has led to its use (now discontinued in many countries) as a rat and ant poison. 

Among the distinctive effects of thallium poisoning are [[alopecia|loss of hair]] (which led it to its initial use as a [[depilatory]] before its toxicity was properly appreciated) and damage to peripheral nerves (victims may experience a sensation of walking on hot coals). Thallium was once an effective murder weapon before its effects became understood, and an antidote ([[prussian blue]]) discovered.

== Treatment and internal decontamination ==

One of the main methods of removing thallium (both radioactive and normal) from humans is to use [[Prussian blue]], which is a solid [[ion exchange]] material which absorbs thallium and releases [[potassium]]. The prussian blue is fed by mouth to the person, and it passes through their digestive system and comes out in the [[Human feces|stool]].<ref>[http://www.bt.cdc.gov/radiation/prussianblue.asp Prussian blue fact sheet] from the [[Centers for Disease Control and Prevention]]</ref>

== References ==
{{reflist}}

== External links ==
*[http://www.webelements.com/webelements/elements/text/Tl/index.html WebElements.com &mdash; Thallium]
*[http://www.emedicine.com/emerg/topic926.htm Toxicity, Thallium]
*[http://toxnet.nlm.nih.gov/cgi-bin/sis/search/r?dbs+hsdb:@term+@na+@rel+thallium,+elemental NLM Hazardous Substances Databank &ndash; Thallium, Elemental]
*[http://www.floridacapitalcases.state.fl.us/case_updates/121965.doc]
*[http://www.atsdr.cdc.gov/tfacts54.html ATSDR - ToxFAQs]

<br>

[[Category:Chemical elements]]
[[Category:Element toxicology]]
[[Category:Thallium]]

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{{SIB}}
[[ar:ثاليوم]]
[[bn:থ্যালিয়াম]]
[[bs:Talijum]]
[[ca:Tal·li]]
[[cs:Thallium]]
[[co:Talliu]]
[[da:Thallium]]
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[[et:Tallium]]
[[el:Θάλλιο]]
[[es:Talio]]
[[eo:Talio]]
[[eu:Talio]]
[[fr:Thallium]]
[[fur:Tali]]
[[ga:Tailliam]]
[[gl:Talio (elemento)]]
[[ko:탈륨]]
[[hy:Թալիում]]
[[hr:Talij]]
[[io:Talio]]
[[id:Talium]]
[[is:Þallín]]
[[it:Tallio]]
[[he:תליום]]
[[sw:Tali]]
[[ht:Talyòm]]
[[ku:Talyûm]]
[[la:Thallium]]
[[lv:Tallijs]]
[[lb:Thallium]]
[[lt:Talis (elementas)]]
[[jbo:jinmrtali]]
[[hu:Tallium]]
[[nl:Thallium]]
[[ja:タリウム]]
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[[nn:Thallium]]
[[oc:Talli]]
[[pl:Tal]]
[[pt:Tálio]]
[[qu:Thalyu]]
[[ru:Таллий]]
[[simple:Thallium]]
[[sk:Tálium]]
[[sr:Талијум]]
[[sh:Talijum]]
[[fi:Tallium]]
[[sv:Tallium]]
[[th:แทลเลียม]]
[[vi:Tali]]
[[tr:Talyum]]
[[uk:Талій]]
[[zh:铊]]

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