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About Thallium

Thallium Bohr

Thallium is the heaviest member of Group 13 on the periodic table, a family that consists of the post-transition “poor metals.” The element is a metal that has a low melting point and is extremely malleable, soft enough to be cut with a knife. Pure elemental thallium is initially lustrous and silvery-gray; however, immediately upon exposure to air the metal begins to form a dull bluish-gray film of thallium(I) oxide on its surface. Prolonged exposure converts the film to a dark brown crust of thallium(III) oxide. When submersed in water, the oxide film disappears and the metal regains its original sheen. Prolonged air and water contact converts the metal to thallium hydroxide. Thallium metal is highly reactive with oxygen and acids and dissolves in nitric acid. French chemist Jean-Baptiste Dumas once called it the "ornithorhynchus paradoxus of metals” (the platypus of metals) because of its similarity to several widely varying elements: lead, silver, potassium, mercury, among others.

There is some debate as to whom the credit for discovering thallium should go. English chemist Sir William Crookes assumed he had obtained tellurium as a byproduct after isolating selenium from residues of sulfuric acid production. When he repeated his experiment years later in 1861, this time focusing on isolating tellurium, he was surprised by the unfamiliar brilliant green lines that appeared in the emission spectrum after burning the sample. This method, known as flame spectroscopy, had been invented several years earlier by chemists Robert Bunsen and Gustav Kirchhoff and used to discover several elements including cesium and rubidium, which they named based on Latin descriptions of the colors of their spectral lines. Fittingly, Crookes named his new element thallium after thallos, Greek for “green twig” or “shoot”. Around the same time, if not earlier, French chemist Claude-Auguste Lamy had identified the element independently from Crookes and isolated it one year later; Lamy, in fact, was more successful at producing the metal than Crookes, exhibiting a pure ingot of thallium at the 1682 London International Exhibition compared to the small amount of powder that Crookes had struggled to produce, and was awarded a medal. Despite this, the discovery of thallium is officially attributed to Crookes thanks to his vocal protest of Lemy’s award.

Thallium is quite scarce in the earth’s crust, at about 0.7 mg/kg, roughly as common as iodine or tungsten. Thallium is not found free in nature, but rather is present in small amounts in ores of iron, copper, heavy-metal sulfides, and in polymetallic rock deposits on the ocean floor. Minerals that contain thallium include crookesite, lorandite, hutchinsonite, pyrites, and orpiment; carlinite (thallium sulfide) is one of the few primarily thallium-based minerals present on earth. Naturally-occurring thallium is composed of two stable isotopes, thallium-203 and -205. 23 radioactive isotopes have also been synthesized. Thallium’s two oxidation states of +1 and +3 (thallous and thallic, respectively) form compounds with very divergent chemical behavior. Thallium(III) compounds and ions resemble those of boron. Thallium(I), the more common form, exhibits behaviour similar to that of the alkali metals and is typically present in potassium ores. Commercially, the element is obtained as a gaseous byproduct of lead and zinc refining, or in the process of obtaining sulfuric acid from pyrites.

Applications for thallium are mostly limited to the fields of electronics, medicine, and infrared optics. Formerly, one of its primary commercial applications centered on thallium sulfate, a toxic, colorless and odorless substance used as a rodenticide; unfortunately, thallium sulfate is also highly toxic to humans, and a string of accidental poisonings led the United States to ban the substance in 1975 in favor of safer alternatives. Thallium in nearly all of its forms is toxic and potentially carcinogenic, and it must be handled with extreme care; the +1 oxidation state’s similarity to alkaline metals causes the ions to be taken up by the cellular potassium ion pumps. Despite this danger, the radioactive isotope thallium-201 is frequently used in medicine in scintigraphy-type stress tests to diagnose clogged arteries and heart disease. 201-Tl binds to heart tissue only with an adequate supply of blood and is quickly eliminated from the patient’s body, emitting gamma particles that can be detected with a scintillation detector and subsequently analysed to determine the robustness of the heart. Some thallium(III) salts are also used as reagents in laboratory science, and thallium hydroxide is a strong base used in the synthesis of organometallic compounds. Thallium iodide in combination with iodides of indium, sodium, scandium, dysprosium, and occasionally tin, are used to produce the high-efficiency white light of metal halide lamps. In addition, certain alloys of thallium are used in bearings, and contact points, and soluble thallium salts serve as additives to gold plating baths to improve the grain size and expedite the plating process.

Thallium has multiple uses in the field of advanced optoelectronics including infrared optics, phosphors, and specialty glasses. The high refractive index of the optical crystals thallium bromoiodide (KRS-5) and thallium bromochloride (KRS-6) make them ideal materials for attenuated total reflection prisms, lenses, and windows in infrared spectrometers and, like other thallium halides, can be used to manufacture fiber optics. Various phosphor and scintillator materials contain thallium either as in compound form, as in thallium selenide, or as host or activator, as in thallium-activated potassium chloride and thallium-activated sodium iodide. Photoelectric cells, photoresistors, and infrared detectors benefit from thallium sulfide’s ability to change electrical conductivity when exposed to infrared radiation; thallium chloride and thallium bromide have also been shown to be photosensitive. Thallium increases the refractive index of glasses; thallium(I) oxide is one material that has been used to fabricate optical glasses in combination with substances like germanium oxide and tellurium, and shatter-proof low melting glasses that become fluid at 125-150 degrees Celsius have been fabricated from thallium in combination with sulfur, selenium, or arsenic.

Thallium compounds have other special properties that give them unique uses. A eutectic thallium-mercury alloy with 8.5% thallium is exhibits a melting point 20 degrees below that of pure mercury, making it applicable in low-temperature thermometers. Strongly basic thallium hydroxide has the ability to take up carbon dioxide from the atmosphere,. Thallium is the only known impurity that causes lead telluride (PbTe) to exhibit superconductivity; the resulting thallium-substituted lead telluride, PbTe:Tl, is a semiconductor and thermoelectric material. Other superconducting materials like thallium barium calcium copper oxides (TBCCO) and various thallium cuprates exhibit T c as high as 127 K.


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Thallium is used most often in the form of thallium sulfide, a compound whose conductivity changes upon exposure to infrared light. High Purity (99.999%) Thallium Oxide (Tl2O) PowderThis property makes the compound useful in photocells. Thallium bromide-iodide crystals have been used as infrared optical materials. Thallium has also been used with sulfur, selenium High Purity (99.999%) Thallium (Tl) Sputtering Targetor arsenic to produce low melting glasses which become fluid between 125-150 °C. These glasses have properties at room temperatures similar to ordinary glasses and are said to be durable and insoluble in water. Thallium oxide has been used to produce glasses with a high index of refraction, and is also used in the manufacture of photo cells. Oxides are available in forms including powders and dense pellets for such uses as optical coating and thin film applications. Thallium is also available in many other specific states, forms and shapes including pellets, rod, wire and granules for evaporation source material purposes.

Thallium Properties

Thallium (Tl) atomic and molecular weight, atomic number and elemental symbolThallium is a post-transition metal that is not found free in nature. It is a Block P, Group 13, Period 6 element. Thallium Bohr Modelhigh purity 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: Tl
Atomic Number: 81
Atomic Weight: 204.3833
Element Category: post-transition metal
Group, Period, Block: 13, 6, p
Color: silvery-gray
Other Names: N/A
Melting Point: 304 °C, 579 °F, 577 K
Boiling Point: 1473 °C, 2683 °F, 1746 K
Density: 11.85 g·cm3
Liquid Density @ Melting Point: 11.22 g·cm3
Density @ 20°C: 11.85 g/cm3
Density of Solid: 11850 kg·m3
Specific Heat: 129 J/(kg K)
Superconductivity Temperature: 2.38 [or -270.77 °C (-455.39 °F)] K
Triple Point: N/A
Critical Point: N/A
Heat of Fusion (kJ·mol-1): 4.31
Heat of Vaporization (kJ·mol-1): 166.1
Heat of Atomization (kJ·mol-1): 182.845
Thermal Conductivity: 46.1 W·m-1·K-1
Thermal Expansion: (25 °C) 29.9 µm·m-1·K-1
Electrical Resistivity: (20 °C) 0.18 µΩ·m
Tensile Strength: N/A
Molar Heat Capacity: 26.32 J·mol-1·K-1
Young's Modulus: 8 GPa
Shear Modulus: 2.8 GPa
Bulk Modulus: 43 GPa
Poisson Ratio: 0.45
Mohs Hardness: 1.2
Vickers Hardness: N/A
Brinell Hardness: 26.4 MPa
Speed of Sound: (20 °C) 818 m·s-1
Pauling Electronegativity: 1.62
Sanderson Electronegativity: 2.25
Allred Rochow Electronegativity: 1.44
Mulliken-Jaffe Electronegativity: 1.96 (sp2 orbital)
Allen Electronegativity: N/A
Pauling Electropositivity: 2.38
Reflectivity (%): N/A
Refractive Index: N/A
Electrons: 81
Protons: 81
Neutrons: 123
Electron Configuration: [Xe] 4f14 5d10 6s2 6p1
Atomic Radius: 170 pm
Atomic Radius,
non-bonded (Å):
Covalent Radius: 145±7 pm
Covalent Radius (Å): 1.44
Van der Waals Radius: 196 pm
Oxidation States: 3, 2, 1 (mildly basic oxide)
Phase: Solid
Crystal Structure: hexagonal close-packed
Magnetic Ordering: diamagnetic
Electron Affinity (kJ·mol-1) 36.375
1st Ionization Energy: 589.36 kJ·mol-1
2nd Ionization Energy: 1971.02 kJ·mol-1
3rd Ionization Energy: 2878.18 kJ·mol-1
CAS Number: 7440-28-0
EC Number: 231-138-1
MDL Number: MFCD00134063
Beilstein Number: N/A
SMILES Identifier: [Tl]
InChI Identifier: InChI=1S/Tl
PubChem CID: 5359464
ChemSpider ID: 4514293
Earth - Total: 3.86 ppb 
Mercury - Total: 0.044 ppb 
Venus - Total: 4.05 ppb
Earth - Seawater (Oceans), ppb by weight: 0.001
Earth - Seawater (Oceans), ppb by atoms: 0.00003
Earth -  Crust (Crustal Rocks), ppb by weight: 530
Earth -  Crust (Crustal Rocks), ppb by atoms: 50
Sun - Total, ppb by weight: 1
Sun - Total, ppb by atoms: 0.01
Stream, ppb by weight: N/A
Stream, ppb by atoms: N/A
Meterorite (Carbonaceous), ppb by weight: 80
Meterorite (Carbonaceous), ppb by atoms: 6
Typical Human Body, ppb by weight: N/A
Typical Human Body, ppb by atom: N/A
Universe, ppb by weight: 0.5
Universe, ppb by atom: 0.003
Discovered By: William Crookes
Discovery Date: 1861
First Isolation: Claude-Auguste Lamy (1862)

Health, Safety & Transportation Information for Thallium

Thallium and its compounds are highly toxic. Safety data for thallium metal, nanomaterials, and compounds can vary widely depending on the form. For potential hazard information, toxicity, and road, sea and air transportation limitations, such as DOT Hazard Class, DOT Number, EU Number, NFPA Health rating and RTECS Class, please see the specific Thallium material or compound referenced in the Products tab. The below information applies to elemental (metallic) Thallium.

Safety Data
Signal Word Danger
Hazard Statements H300-H330-H373-H413
Hazard Codes T+
Risk Codes 26/28-33-53
Safety Precautions 13-28-45-61
RTECS Number XG3425000
Transport Information UN 3288 6.1/PG 2
WGK Germany 3
Globally Harmonized System of
Classification and Labelling (GHS)
Skull and Crossbones-Acute Toxicity  Health Hazard
Review and Print SDS for Thallium Metal


Date Created: 05/15/2015
Date Revised: 05/15/2015


Product Name: Thallium Metal

Product Number: All applicable American Elements product codes, e.g. TL-M-02, TL-M-03, TL-M-04, TL-M-05

CAS #: 7440-28-0

Relevant identified uses of the substance: Scientific research and development

Supplier details:
American Elements
1093 Broxton Ave. Suite 2000
Los Angeles, CA 90024
Tel: +1 310-208-0551
Fax: +1 310-208-0351

Emergency telephone number:
Domestic, North America +1 800-424-9300
International +1 703-527-3887


Classification of the substance or mixture in accordance with 29 CFR 1910 (OSHA HCS)
GHS06 Skull and crossbones
Acute Tox. 2 H300 Fatal if swallowed.
Acute Tox. 2 H330 Fatal if inhaled.
GHS08 Health hazard
STOT RE 2 H373 May cause damage to organs through prolonged or repeated exposure.
Hazards not otherwise classified No information known.
Label elements
GHS label elements The product is classified and labeled in accordance with 29 CFR 1910 (OSHA HCS)
Hazard pictograms

Skull and Crossbones - GHS06 Health Hazard - GHS08

Signal word Danger
Hazard statements
H300+H330 Fatal if swallowed or if inhaled.
H373 May cause damage to organs through prolonged or repeated exposure.
Precautionary statements
P260 Do not breathe dust/fume/gas/mist/vapours/spray.
P284 [In case of inadequate ventilation] wear respiratory protection.
P301+P310 IF SWALLOWED: Immediately call a POISON CENTER/ doctor/…
P320 Specific treatment is urgent (see on this label).
P405 Store locked up.
P501 Dispose of contents/container in accordance with local/regional/national/international regulations.
WHMIS classification
D1A - Very toxic material causing immediate and serious toxic effects
Classification system
HMIS ratings (scale 0-4)
(Hazardous Materials Identification System)

Health (acute effects) = 1
Flammability = 0
Physical Hazard = 0
Other hazards
Results of PBT and vPvB assessment
PBT: Not applicable.
vPvB: Not applicable.


Chemical characterization: Substances
CAS# Description:
7440-28-0 Thallium
Identification number(s):
EC number: 231-138-1
Index number: 081-001-00-3


Description of first aid measures
General information
Immediately remove any clothing soiled by the product.
Remove breathing apparatus only after contaminated clothing has been completely removed.
In case of irregular breathing or respiratory arrest provide artificial respiration.
No special measures required.
After inhalation Seek medical treatment in case of complaints.
After skin contact Generally the product does not irritate the skin.
After eye contact Rinse opened eye for several minutes under running water. If symptoms persist, consult a doctor.
After swallowing Do not induce vomiting; immediately call for medical help.
Information for doctor
Most important symptoms and effects, both acute and delayed No further relevant information available.
Indication of any immediate medical attention and special treatment needed No further relevant information available.


Extinguishing media
Suitable extinguishing agents Special powder for metal fires. Do not use water.
For safety reasons unsuitable extinguishing agents Water
Special hazards arising from the substance or mixture
If this product is involved in a fire, the following can be released:
Toxic metal oxide fume
Advice for firefighters
Protective equipment: No special measures required.


Personal precautions, protective equipment and emergency procedures Not required.
Environmental precautions: Do not allow material to be released to the environment without proper governmental permits.
Methods and material for containment and cleaning up:
Dispose of contaminated material as waste according to section 13.
Ensure adequate ventilation.
Prevention of secondary hazards: No special measures required.
Reference to other sections
See Section 7 for information on safe handling
See Section 8 for information on personal protection equipment.
See Section 13 for disposal information.


Precautions for safe handling
Keep container tightly sealed.
Store in cool, dry place in tightly closed containers.
Ensure good ventilation at the workplace.
Open and handle container with care.
Information about protection against explosions and fires: No special measures required.
Conditions for safe storage, including any incompatibilities
Requirements to be met by storerooms and receptacles: No special requirements.
Information about storage in one common storage facility: Do not store together with oxidizing and acidic materials.
Further information about storage conditions:
Keep container tightly sealed.
Store in cool, dry conditions in well sealed containers.
Specific end use(s) No further relevant information available.


Additional information about design of technical systems: No further data; see section 7.
Control parameters
Components with limit values that require monitoring at the workplace:
7440-28-0 Thallium (100.0%)
PEL (USA) Long-term value: 0.1 mg/m³
as Tl; Skin
REL (USA) Long-term value: 0.1 mg/m³
as Tl; Skin
TLV (USA) Long-term value: 0.02* mg/m³
as Tl; *inhalable fraction; Skin
EL (Canada) Long-term value: 0.1 mg/m³
as Tl; Skin
EV (Canada) Long-term value: 0.1 mg/m³
watersoluble compounds, Skin
Additional information: No data
Exposure controls
Personal protective equipment
General protective and hygienic measures
The usual precautionary measures for handling chemicals should be followed.
Store protective clothing separately.
Maintain an ergonomically appropriate working environment.
Breathing equipment:
Not required.
Use self-contained respiratory protective device in emergency situations.
Protection of hands: Not required.
Penetration time of glove material (in minutes) Not determined
Eye protection: Safety glasses
Body protection: Protective work clothing.


Information on basic physical and chemical properties
General Information
Form: Solid in various forms
Color: Not determined
Odor: Odorless
Odor threshold: Not determined.
pH-value: Not applicable.
Change in condition
Melting point/Melting range: 303.5 °C (578 °F)
Boiling point/Boiling range: 1457 °C (2655 °F)
Sublimation temperature / start: Not determined
Flammability (solid, gaseous) Not determined.
Ignition temperature: Not determined
Decomposition temperature: Not determined
Auto igniting: Not determined.
Danger of explosion: Not determined.
Explosion limits:
Lower: Not determined
Upper: Not determined
Vapor pressure at 473 °C (883 °F): 0.13 hPa
Density at 20 °C (68 °F): 11.85 g/cm³ (98.888 lbs/gal)
Relative density Not determined.
Vapor density Not applicable.
Evaporation rate Not applicable.
Solubility in / Miscibility with
Water: Not determined
Partition coefficient (n-octanol/water): Not determined.
dynamic: Not applicable.
kinematic: Not applicable.
Other information No further relevant information available.


Reactivity No information known.
Chemical stability Stable under recommended storage conditions.
Thermal decomposition / conditions to be avoided: Decomposition will not occur if used and stored according to specifications.
Possibility of hazardous reactions No dangerous reactions known
Conditions to avoid No further relevant information available.
Incompatible materials: Oxidizing agents
Hazardous decomposition products: Toxic metal oxide fume


Information on toxicological effects
Acute toxicity:
Fatal if inhaled.
Fatal if swallowed.
The Registry of Toxic Effects of Chemical Substances (RTECS) contains acute toxicity data for components in this product.
LD/LC50 values that are relevant for classification: No data
Skin irritation or corrosion: Powder: irritant effect
Eye irritation or corrosion: Powder: irritant effect
Sensitization: No sensitizing effects known.
Germ cell mutagenicity: No effects known.
Carcinogenicity: EPA-I: Data are inadequate for an assessment of human carcinogenic potential.
Reproductive toxicity: No effects known.
Specific target organ system toxicity - repeated exposure: May cause damage to organs through prolonged or repeated exposure.
Specific target organ system toxicity - single exposure: No effects known.
Aspiration hazard: No effects known.
Subacute to chronic toxicity: The Registry of Toxic Effects of Chemical Substances (RTECS) contains multiple dose toxicity data for this substance.
Additional toxicological information: To the best of our knowledge the acute and chronic toxicity of this substance is not fully known.


Aquatic toxicity: No further relevant information available.
Persistence and degradability No further relevant information available.
Bioaccumulative potential No further relevant information available.
Mobility in soil No further relevant information available.
Additional ecological information:
General notes:
Do not allow material to be released to the environment without proper governmental permits.
Do not allow product to reach ground water, water course or sewage system, even in small quantities.
Danger to drinking water if even extremely small quantities leak into the ground.
May cause long lasting harmful effects to aquatic life.
Avoid transfer into the environment.
Results of PBT and vPvB assessment
PBT: Not applicable.
vPvB: Not applicable.
Other adverse effects No further relevant information available.


Waste treatment methods
Recommendation Consult state, local or national regulations to ensure proper disposal.
Uncleaned packagings:
Recommendation: Disposal must be made according to official regulations.


DOT, ADN, IMDG, IATA Not applicable
UN proper shipping name
DOT, ADN, IMDG, IATA Not applicable
Transport hazard class(es)
Class Not applicable
Packing group
DOT, IMDG, IATA Not applicable
Environmental hazards: Not applicable.
Special precautions for user Not applicable.
Transport in bulk according to Annex II of MARPOL73/78 and the IBC Code Not applicable.
Transport/Additional information:
Marine Pollutant (DOT): No
UN "Model Regulation": -


Safety, health and environmental regulations/legislation specific for the substance or mixture
GHS label elements The product is classified and labeled in accordance with 29 CFR 1910 (OSHA HCS)
Hazard pictograms
Signal word Danger
Hazard statements
H300+H330 Fatal if swallowed or if inhaled.
H373 May cause damage to organs through prolonged or repeated exposure.
Precautionary statements
P260 Do not breathe dust/fume/gas/mist/vapours/spray.
P284 [In case of inadequate ventilation] wear respiratory protection.
P301+P310 IF SWALLOWED: Immediately call a POISON CENTER/ doctor/…
P320 Specific treatment is urgent (see on this label).
P405 Store locked up.
P501 Dispose of contents/container in accordance with local/regional/national/international regulations.
National regulations
All components of this product are listed in the U.S. Environmental Protection Agency Toxic Substances Control Act Chemical substance Inventory.
All components of this product are listed on the Canadian Domestic Substances List (DSL).
SARA Section 313 (specific toxic chemical listings)
7440-28-0 Thallium
California Proposition 65
Prop 65 - Chemicals known to cause cancer Substance is not listed.
Prop 65 - Developmental toxicity Substance is not listed.
Prop 65 - Developmental toxicity, female Substance is not listed.
Prop 65 - Developmental toxicity, male Substance is not listed.
Information about limitation of use:
For use only by technically qualified individuals.
This product is subject to the reporting requirements of section 313 of the Emergency Planning and Community Right to Know Act of 1986 and 40CFR372.
Other regulations, limitations and prohibitive regulations
Substance of Very High Concern (SVHC) according to the REACH Regulations (EC) No. 1907/2006. Substance is not listed.
The conditions of restrictions according to Article 67 and Annex XVII of the Regulation (EC) No 1907/2006 (REACH) for the manufacturing, placing on the
market and use must be observed.
Substance is not listed.
Annex XIV of the REACH Regulations (requiring Authorisation for use) Substance is not listed.
Chemical safety assessment: A Chemical Safety Assessment has not been carried out.


Safety Data Sheet according to Regulation (EC) No. 1907/2006 (REACH). The above information is believed to be correct but does not purport to be all inclusive and shall be used only as a guide. The information in this document is based on the present state of our knowledge and is applicable to the product with regard to appropriate safety precautions. It does not represent any guarantee of the properties of the product. American Elements shall not be held liable for any damage resulting from handling or from contact with the above product. See reverse side of invoice or packing slip for additional terms and conditions of sale. COPYRIGHT 1997-2016 AMERICAN ELEMENTS. LICENSED GRANTED TO MAKE UNLIMITED PAPER COPIES FOR INTERNAL USE ONLY.

Thallium Isotopes

Thallium (Tl) has 37 isotopes with atomic masses ranging from 176 to 212. Only 203Tl and 205Tl are stable.

Nuclide Isotopic Mass Half-Life Mode of Decay Nuclear Spin Magnetic Moment Binding Energy (MeV) Natural Abundance
(% by atom)
176Tl 176.00059(21)# 5.2(+30-14) ms Unknown (3-,4-,5-) N/A 1330.97 -
177Tl 176.996427(27) 18(5) ms p to 176Hg (1/2+) N/A 1348.36 -
178Tl 177.99490(12)# 255(10) ms a to 174Au N/A N/A 1356.44 -
179Tl 178.99109(5) 270(30) ms a to 175Au (1/2+) N/A 1364.52 -
180Tl 179.98991(13)# 1.5(2) s a to 176Au; ß+ to 180Hg; SF N/A N/A 1381.91 -
181Tl 180.986257(10) 3.2(3) s a to 177Au; ß+ to 181Hg 1/2+# N/A 1389.99 -
182Tl 181.98567(8) 2.0(3) s ß+ to 182Hg; a to 178Au 2-# N/A 1398.07 -
183Tl 182.982193(10) 6.9(7) s ß+ to 183Hg; a to 179Au 1/2+# N/A 1406.15 -
184Tl 183.98187(5) 9.7(6) s ß+ to 184Hg 2-# N/A 1414.23 -
185Tl 184.97879(6) 19.5(5) s a to 181Au; ß+ to 185Hg 1/2+# N/A 1431.62 -
186Tl 185.97833(20) 40# s ß+ to 186Hg; a to 182Au (2-) N/A 1439.7 -
187Tl 186.975906(9) ~51 s ß+ to 187Hg (1/2+) N/A 1447.78 -
188Tl 187.97601(4) 71(2) s ß+ to 188Hg (2-) N/A 1455.86 -
189Tl 188.973588(12) 2.3(2) min ß+ to 189Hg (1/2+) N/A 1463.94 -
190Tl 189.97388(5) 2.6(3) min ß+ to 190Hg 2(-) N/A 1472.02 -
191Tl 190.971786(8) 20# min ß+ to 191Hg (1/2+) N/A 1480.09 -
192Tl 191.97223(3) 9.6(4) min ß+ to 192Hg (2-) N/A 1488.17 -
193Tl 192.97067(12) 21.6(8) min ß+ to 193Hg 1/2(+#) N/A 1496.25 -
194Tl 193.97120(15) 33.0(5) min ß+ to 194Hg; a to 190Au 2- N/A 1504.33 -
195Tl 194.969774(15) 1.16(5) h ß+ to 195Hg 1/2+ N/A 1521.73 -
196Tl 195.970481(13) 1.84(3) h ß+ to 196Hg 2- N/A 1520.49 -
197Tl 196.969575(18) 2.84(4) h ß+ to 197Hg; IT 1/2+ N/A 1537.88 -
198Tl 197.97048(9) 5.3(5) h ß+ to 198Hg 2- N/A 1536.65 -
199Tl 198.96988(3) 7.42(8) h ß+ to 199Hg; IT 1/2+ N/A 1554.04 -
200Tl 199.970963(6) 26.1(1) h EC to 200Hg 2- 0.04 1552.8 -
201Tl 200.970819(16) 72.912(17) h EC to 201Hg 1/2+ 1.605 1560.88 -
202Tl 201.972106(16) 12.23(2) d EC to 202Hg 2- 0.06 1568.96 -
203Tl 202.9723442(14) STABLE - 1/2+ 1.622257 1577.04 29.524
204Tl 203.9738635(13) 3.78(2) y EC to 204Hg; ß- to 204Pb 2- 0.09 1585.12 -
205Tl 204.9744275(14) STABLE - 1/2+ 1.6382135 1593.2 70.476
206Tl 205.9761103(15) 4.200(17) min ß- to 206Pb; IT 0- N/A 1601.28 -
207Tl 206.977419(6) 4.77(2) min ß- to 207Pb 1/2+ N/A 1609.35 -
208Tl 207.9820187(21) 3.053(4) min ß- to 208Pb 5(+) N/A 1608.12 -
209Tl 208.985359(8) 2.161(7) min ß- to 209Pb (1/2+) N/A 1616.2 -
210Tl 209.990074(12) 1.30(3) min ß- to 210Pb; ß- + n to 209Pb (5+)# N/A 1614.96 -
211Tl 210.99348(22)# 1# min [>300 ns] Unknown 1/2+# N/A 1623.04 -
212Tl 211.99823(32)# 30# s [>300 ns] Unknown 5+# N/A 1631.11 -