| Atomic Mass | 204.3833 |
|---|---|
| Electron Configuration | [Xe]6s24f145d106p1 |
| Oxidation States | +3, +1 |
| Year Discovered | 1861 |
| Atomic Mass | 204.3833 |
|---|---|
| Electron Configuration | [Xe]6s24f145d106p1 |
| Oxidation States | +3, +1 |
| Year Discovered | 1861 |
| Element Name | Thallium |
|---|---|
| Element Symbol | Tl |
| InChI | InChI=1S/Tl |
| InChIKey | BKVIYDNLLOSFOA-UHFFFAOYSA-N |
| Atomic Weight |
[204.382, 204.385] 204.3833 204.38 [204.382,204.385] |
|---|---|
| Electron Configuration |
[Xe]6s24f145d106p1 |
| Atomic Radius |
Van der Waals Atomic Radius : 196 pm (Van der Waals) Empirical Atomic Radius : 190pm (Empirical) Covalent Atomic Radius : 145(7) pm (Covalent) |
| Oxidation States |
+3, +1 3, 2, 1, -1, -2, -5 |
| Ground Level |
2P°1/2 |
| Ionization Energy |
6.108 eV 6.1082873 ± 0.0000012 eV |
| Electronegativity |
Pauling Scale Electronegativity : 1.62(Pauling Scale) Allen Scale Electronegativity : 1.789(Allen Scale) |
| Electron Affinity |
0.2eV 0.32eV |
| Atomic Spectra |
Lines Holdings Levels Holdings |
| Physical Description |
Solid |
| Element Classification |
Metal |
| Element Period Number |
6 |
| Element Group Number |
13 |
| Density |
11.8 grams per cubic centimeter |
| Melting Point |
577 K (304°C or 579°F) 304°C |
| Boiling Point |
1746 K (1473°C or 2683°F) 1473°C |
| Estimated Crustal Abundance |
8.5×10-1 milligrams per kilogram |
| Estimated Oceanic Abundance |
1.9×10-5 milligrams per liter |
The name derives from the Greek thallos for "green shoot" or "twig" because of the bright green line in its spectrum. Thallium was discovered by the English physicist and chemist William Crookes in 1861. Metallic thallium was first isolated by the French chemist Claude-Auguste Lamy in 1862.
Thallium was discovered spectroscopically by Sir William Crookes, an English chemist, in 1861. Crooks had obtained the sludge left over from the production of sulfuric acid (H2SO4) from a friend. After removing all of the selenium from the sludge, he inspected it with a device known as a spectroscope to look for signs of tellurium. Rather than seeing the yellow spectral lines produced by tellurium, he observed a bright green line that no one had ever seen before. He named the new element that was producing the green line thallium, after the greek word for 'green twig', thallos. He isolated samples of thallium the next year. Thallium is found in the minerals crooksite (CuThSe), lorandite (TlAsS2) and hutchinsonite ((Pb, Tl)2As5S9), but is usually obtained as a byproduct of the production of sulfuric acid or as a byproduct of refining zinc or lead.
From Greek thallos, meanin a green shoot or twig. Thallium was discovered spectroscopically in 1861 by Crookes. The element was named after the beautiful green spectral line, which identified the element. The metal was isolated both by Crookes and by Lamy in 1862 at about the same time.
| Year | Atomic Weight (uncertainty) [u] | Reference |
|---|---|---|
| 2009 | [204.382, 204.385] | https://doi.org/10.1351/PAC-REP-10-09-14 |
| 1985 | 204.3833(2) | https://doi.org/10.1351/pac198658121677 |
| 1979 | 204.383(1) | https://doi.org/10.1351/pac198052102349 |
| 1969 | 204.37(3) | https://doi.org/10.1351/pac197021010091 |
| 1961 | 204.37 | https://doi.org/10.1021/ja00881a001 |
| 1925 | 204.39 | https://doi.org/10.1039/CT9252700913 |
| 1909 | 204.0 | https://doi.org/10.1021/ja01931a001 |
| 1902 | 204.1 | https://doi.org/10.1007/BF01370337 |
| Year | Isotope | Abundance (uncertainty) | Reference |
|---|---|---|---|
| 2013 | 203Tl | [0.2944, 0.2959] | https://doi.org/10.1515/pac-2015-0503 |
| 2013 | 205Tl | [0.7041, 0.7056] | https://doi.org/10.1515/pac-2015-0503 |
| 2001 | 203Tl | 0.2952(1) | https://doi.org/10.1063/1.1836764 |
| 2001 | 205Tl | 0.7048(1) | https://doi.org/10.1063/1.1836764 |
| 1989 | 203Tl | 0.295 24(14) | https://doi.org/10.1351/pac199163070991 |
| 1989 | 205Tl | 0.704 76(14) | https://doi.org/10.1351/pac199163070991 |
| 1979 | 203Tl | 0.295 24(18) | https://doi.org/10.1351/pac198052102349 |
| 1979 | 205Tl | 0.704 76(18) | https://doi.org/10.1351/pac198052102349 |
| 1975 | 203Tl | 0.295 | https://doi.org/10.1351/pac197647010075 |
| 1975 | 205Tl | 0.705 | https://doi.org/10.1351/pac197647010075 |
When freshly exposed to air, thallium exhibits a metallic luster, but soon develops a bluish-gray tinge, resembling lead in appearance. A heavy oxide builds up on thallium if left in air, and in the presence of water the hydride is formed. The metal is very soft and malleable. It can be cut with a knife. Twenty five isotopic forms of thallium, with atomic masses ranging from 184 to 210 are recognized. Natural thallium is a mixture of two isotopes. A mercury-thallium alloy, which forms a eutectic at 8.5% thallium, is reported to freeze at -60C, some 20 degrees below the freezing point of mercury.
There are no uses for metallic thallium since pure thallium quickly combines with oxygen and water vapor from the atmosphere, forming a black, powdery substance. Thallium, used in conjunction with sulfur or selenium and arsenic, forms low melting glass. Thallium sulfate (Tl2SO4), an odorless, tasteless thallium compound, was once used as a rat and ant poison, although it has been banned from household use in the United States since 1974. Thallium sulfide (Tl2S), thallium iodide (TlI) and thallium bromide (TlBr) are all compounds used in devices to detect infrared radiation.
Thallium sulfate has been widely employed as a rodenticide and ant killer. It is odorless and tasteless, giving no warning of its presence. Its use, however, has been prohibited in the U.S. since 1975 as a household insecticide and rodenticide. The electrical conductivity of thallium sulfide changes with exposure to infrared light, and this compound is used in photocells. Thallium bromide-iodide crystals have been used as infrared optical materials. Thallium has been used, with sulfur or selenium and arsenic, to produce low melting glasses with become fluid between 125 and 150C. 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 used in the manufacture of photo cells. Thallium has been used in treating ringworm and other skin infections; however, its use has been limited because of the narrow margin between toxicity and therapeutic benefits.
Thallium occurs in crooksite, lorandite, and hutchinsonite. It is also present in pyrites and is recovered from the roasting of this ore in connection with the production of sulfuric acid. It is also obtained from the smelting of lead and zinc ores. Extraction is somewhat complex and depends on the source of the thallium. Manganese nodules, found on the ocean floor, contain thallium.
See more information at the Thallium compound page.
| CID | Name | Formula | SMILES | Molecular Weight |
|---|---|---|---|---|
| 5359464 | thallium | Tl | [Tl] | 204.383 |
| 5461982 | thallium-201 | Tl | [201Tl] | 200.9708 |
| 105005 | thallium(1+) | Tl+ | [Tl+] | 204.383 |
| 16019994 | thallium-203 | Tl | [203Tl] | 202.97234 |
| 105172 | thallium(3+) | Tl+3 | [Tl+3] | 204.383 |
| 6335516 | thallium-204 | Tl | [204Tl] | 203.97386 |
| 6335611 | thallium-208 | Tl | [208Tl] | 207.98202 |
| 6337070 | thallium-200 | Tl | [200Tl] | 199.97096 |
| 6337071 | thallium-202 | Tl | [202Tl] | 201.97211 |
| 16019993 | thallium-205 | Tl | [205Tl] | 204.97443 |
| 25087151 | thallium-207 | Tl | [207Tl] | 206.97742 |
| 10130399 | thallium-201(1+) | Tl+ | [201Tl+] | 200.9708 |
| 6337571 | thallium-199 | Tl | [199Tl] | 198.9699 |
| 6337570 | thallium-206 | Tl | [206Tl] | 205.97611 |
| 6337634 | thallium-195 | Tl | [195Tl] | 194.9698 |
| 6337535 | thallium-194 | Tl | [194Tl] | 193.9711 |
| 6337615 | thallium-197 | Tl | [197Tl] | 196.9696 |
| 6337662 | thallium-209 | Tl | [209Tl] | 208.98535 |
| 44145119 | thallium-210 | Tl | [210Tl] | 209.9901 |
| 6337590 | thallium-198 | Tl | [198Tl] | 197.97045 |
| 165412135 | thallium-199(1+) | Tl+ | [199Tl+] | 198.9699 |
The element and its compounds are toxic and should be handled carefully. Contact of the metal with skin is dangerous, and when melting the metal adequate ventilation should be provided. Exposure to thallium (soluble compounds) - skin, as Tl, should not exceed 0.1 mg/m3 (8-hour time-weighted average - 40-hour work week). Thallium is suspected of carcinogenic potential for man.
| Stable Isotope Count | 2 |
|---|
Because molecules, atoms, and ions of the stable isotopes of thallium possess slightly different physical and chemical properties, they commonly will be fractionated during physical, chemical, and biological processes, giving rise to variations in isotopic abundances and in atomic weights. There are substantial variations in the isotopic abundances of thallium in natural terrestrial materials (Fig. IUPAC.81.1). These variations are useful in investigating the origin of substances and studying environmental, hydrological, and geological processes [538]. The isotope-amount ratio n(205Tl)/n(203Tl) has been used to study how trace metals are transported and distributed in hydrothermal fluids [538]. The n(205Tl)/n(203Tl) ratio has also been used to study the cycling, distribution, and behavior of thallium in the marine environment [538].
![Fig. IUPAC.81.1: Variation in atomic weight with isotopic composition of selected thallium-bearing materials (modified from [13], [17]).](https://pubchem.ncbi.nlm.nih.gov/images/iupac/j_pac-2015-0703_fig_109.jpg)
201Tl scintigraphy is used to detect coronary artery disease [539]. Imaging of 201Tl (with a half-life of 3 days), can be used for exercise perfusion tests of the myocardium (muscular tissue of the heart), which determine damage to the heart caused by a heart attack or by heart disease (Fig. IUPAC.81.2) [539].
![Fig. IUPAC.81.2: During exercise myocardium perfusion tests, a patient will exercise on a treadmill until they have reached their maximal exercise point (determined by heart rate and age). Once they reach their maximal exercise point, a radionuclide (usually of thallium or technetium) is injected into the intravenous line in their arm, and the patient continues to exercise for a few more minutes. Once the radionuclide reaches the heart, the patient lies flat on a table and a gamma camera takes pictures of the heart for about 30 min. The areas of decreased blood flow or damaged tissue will be illuminated by the radionuclide. (Image source: National Heart Lung and Blood Institute, Diseases and Conditions Index, National Institutes of Health) [540].](https://pubchem.ncbi.nlm.nih.gov/images/iupac/j_pac-2015-0703_fig_110.jpg)
203Tl is used in the production of 201Tl via the 203Tl (p, 3 n) 201Pb reaction, which is followed by a subsequent electron capture decay reaction of 201Pb to finally yield 201Tl. 205Tl is used as an alternative target in the production of 201Tl.
| Isotope | Atomic Mass (uncertainty) [u] | Abundance (uncertainty) |
|---|---|---|
| 203Tl | 202.972 344(8) | [0.2944, 0.2959] |
| 205Tl | 204.974 427(8) | [0.7041, 0.7056] |
| Isotope | Atomic Mass (uncertainty) [u] | Abundance (uncertainty) |
|---|---|---|
| 203Tl | 202.9723446(14) | 0.2952(1) |
| 205Tl | 204.9744278(14) | 0.7048(1) |
| Nuclide | Atomic Mass and Uncertainty [u] | Half Life and Uncertainty | Discovery Year | Decay Modes, Intensities and Uncertainties [%] |
|---|---|---|---|---|
| 176Tl | 176.000627731 ± 0.000089166 | 6.2 ms ± 2.3 | 2004 | p≈100%; α ?; β+ ? |
| 177Tl | 176.996414252 ± 0.000023218 | 18 ms ± 5 | 1999 | α=73±1.3%; p ? |
| 177Tlm | 176.996414252 ± 0.000023218 | 230 us ± 40 | 1997 | p=51±0.8%; α=49±0.8% |
| 178Tl | 177.995047 ± 0.00011 [Estimated] | 255 ms ± 9 | 1997 | α=62±0.2%; β+=38±0.2%; β+SF=0.15±0.6% |
| 179Tl | 178.991122185 ± 0.000041495 | 437 ms ± 9 | 1983 | α=60±0.2%; β+ ? |
| 179Tlm | 178.991122185 ± 0.000041495 | 1.41 ms ± 0.02 | 1983 | α≈100%; IT ?; β+ ? |
| 179Tln | 178.991122185 ± 0.000041495 | 119 ns ± 14 | 2018 | IT=100% |
| 180Tl | 179.989918950 ± 0.000075058 | 1.09 s ± 0.01 | 1987 | β+=93±0.3%; α=7±0.3%; β+SF=0.0032±0.2% |
| 181Tl | 180.986259978 ± 0.000009771 | 2.9 s ± 0.1 | 1996 | β+ ?; α=8.6±0.6% |
| 181Tlm | 180.986259978 ± 0.000009771 | 1.40 ms ± 0.03 | 1984 | IT=99.60±0.4%; α=0.40±0.6%; β+ ? |
| 182Tl | 181.985692649 ± 0.000012856 | 1.9 s ± 0.1 | 1991 | β+≈100%; α>0.49%; β+SF<3.4e-6% |
| 182Tlm | 181.985692649 ± 0.000012856 | 3.1 s ± 1.0 | 1991 | β+≈100%; α=2.5±1.4%; IT ? |
| 182Tlp | 181.985692649 ± 0.000012856 | Not-specified | ||
| 183Tl | 182.982192843 ± 0.000010017 | 6.9 s ± 0.7 | 1980 | β+=?; α ? |
| 183Tlm | 182.982192843 ± 0.000010017 | 53.3 ms ± 0.3 | 1980 | IT ?; α=1.5±0.3%; β+ ? |
| 183Tln | 182.982192843 ± 0.000010017 | 1.48 us ± 0.10 | 2001 | IT=100% |
| 184Tl | 183.981874973 ± 0.000010747 | 9.5 s ± 0.2 | 1976 | β+=98.78±3%; α=1.22±3% |
| 184Tlm | 183.981874973 ± 0.000010747 | 10.6 s ± 0.5 | 2016 | β+=99.53±0.6%; IT ?; α=0.47±0.6% |
| 184Tln | 183.981874973 ± 0.000010747 | 47.1 ms ± 0.7 | 1984 | IT≈100%; α=0.089±1.9% |
| 185Tl | 184.978789189 ± 0.000022194 | 19.5 s ± 0.5 | 1976 | β+≈100%; α ? |
| 185Tlm | 184.978789189 ± 0.000022194 | 1.93 s ± 0.08 | 1976 | IT≈100%; α=?; β+ ? |
| 186Tl | 185.978654787 ± 0.000022276 | 3.5 s ± 0.5 | 1975 | β+ ?; α=? |
| 186Tlm | 185.978654787 ± 0.000022276 | 27.5 s ± 1.0 | 1975 | β+≈100%; α≈0.006% |
| 186Tln | 185.978654787 ± 0.000022276 | 3.40 s ± 0.09 | 1977 | IT<94.1±0.3%; β+>5.9±0.3% |
| 187Tl | 186.975904740 ± 0.00000864 | ~51 s | 1976 | β+≈100%; α ? |
| 187Tlm | 186.975904740 ± 0.00000864 | 15.60 s ± 0.12 | 1976 | IT=?; β+=?; α=0.15±0.5% |
| 187Tln | 186.975904740 ± 0.00000864 | 1.11 us ± 0.7 | 2000 | IT=100% |
| 187Tlp | 186.975904740 ± 0.00000864 | 693 ns ± 38 | 2000 | IT=100% |
| 188Tl | 187.976020886 ± 0.000032103 | 71 s ± 2 | 1970 | β+=100% |
| 188Tlm | 187.976020886 ± 0.000032103 | 71.5 s ± 1.5 | 1970 | β+=100% |
| 188Tln | 187.976020886 ± 0.000032103 | 41 ms ± 4 | 1981 | IT≈100%; β+ ? |
| 189Tl | 188.973573525 ± 0.000008983 | 2.3 m ± 0.2 | 1972 | β+=100% |
| 189Tlm | 188.973573525 ± 0.000008983 | 1.4 m ± 0.1 | 1972 | β+≈100%; IT ? |
| 190Tl | 189.973841771 ± 0.000007784 | 2.6 m ± 0.3 | 1970 | β+=100% |
| 190Tlm | 189.973841771 ± 0.000007784 | 3.6 m ± 0.3 | 1970 | β+=100% |
| 190Tln | 189.973841771 ± 0.000007784 | 750 us ± 40 | 1981 | IT=100% |
| 190Tlp | 189.973841771 ± 0.000007784 | 60 ms [Estimated] | 1991 | IT=100% |
| 191Tl | 190.971784093 ± 0.000007889 | 20 m [Estimated] | 1974 | β+ ? |
| 191Tlm | 190.971784093 ± 0.000007889 | 5.22 m ± 0.16 | 1970 | β+=100% |
| 192Tl | 191.972225000 ± 0.000034 | 9.6 m ± 0.4 | 1961 | β+=100% |
| 192Tlm | 191.972225000 ± 0.000034 | 10.8 m ± 0.2 | 1961 | β+=100% |
| 192Tln | 191.972225000 ± 0.000034 | 296 ns ± 5 | 1980 | IT=100% |
| 192Tlp | 191.972225000 ± 0.000034 | Not-specified | 1991 | α=100% |
| 193Tl | 192.970501994 ± 0.0000072 | 21.6 m ± 0.8 | 1960 | β+=100% |
| 193Tlm | 192.970501994 ± 0.0000072 | 2.11 m ± 0.15 | 1963 | IT≈75%; β+≈25% |
| 194Tl | 193.971081408 ± 0.000015 | 33.0 m ± 0.5 | 1960 | β+=100%; α ? |
| 194Tlm | 193.971081408 ± 0.000015 | 32.8 m ± 0.2 | 1960 | β+=100% |
| 195Tl | 194.969774052 ± 0.000011944 | 1.16 h ± 0.05 | 1955 | β+=100% |
| 195Tlm | 194.969774052 ± 0.000011944 | 3.6 s ± 0.4 | 1957 | IT=100% |
| 196Tl | 195.970481189 ± 0.000013 | 1.84 h ± 0.03 | 1955 | β+=100% |
| 196Tlm | 195.970481189 ± 0.000013 | 1.41 h ± 0.02 | 1960 | β+=96.2±0.4%; IT=3.8±0.4% |
| 197Tl | 196.969560492 ± 0.000014573 | 2.84 h ± 0.04 | 1955 | β+=100% |
| 197Tlm | 196.969560492 ± 0.000014573 | 540 ms ± 10 | 1953 | IT=100% |
| 198Tl | 197.970446669 ± 0.0000081 | 5.3 h ± 0.5 | 1949 | β+=100% |
| 198Tlm | 197.970446669 ± 0.0000081 | 1.87 h ± 0.03 | 1949 | β+=55.9±2.3%; IT=44.1±2.3% |
| 198Tln | 197.970446669 ± 0.0000081 | 150 ns ± 40 | 1977 | IT=100% |
| 198Tlp | 197.970446669 ± 0.0000081 | 32.1 ms ± 1.0 | 1975 | IT=100% |
| 199Tl | 198.969877000 ± 0.00003 | 7.42 h ± 0.08 | 1949 | β+=100% |
| 199Tlm | 198.969877000 ± 0.00003 | 28.4 ms ± 0.2 | 1963 | IT=100% |
| 200Tl | 199.970963608 ± 0.000006182 | 26.1 h ± 0.1 | 1949 | β+=100% |
| 200Tlm | 199.970963608 ± 0.000006182 | 34.0 ms ± 0.9 | 1963 | IT=100% |
| 200Tln | 199.970963608 ± 0.000006182 | 397 ns ± 17 | 1972 | IT=100% |
| 201Tl | 200.970820235 ± 0.000015228 | 3.0421 d ± 0.0008 | 1950 | ε=100% |
| 201Tlm | 200.970820235 ± 0.000015228 | 2.01 ms ± 0.07 | 1962 | IT=100% |
| 202Tl | 201.972108874 ± 0.000001972 | 12.31 d ± 0.08 | 1940 | ε=100% |
| 202Tlm | 201.972108874 ± 0.000001972 | 591 us ± 3 | 1958 | IT=100% |
| 203Tl | 202.972344098 ± 0.000001257 | Stable | 1931 | IS=29.515±4.4% |
| 203Tlm | 202.972344098 ± 0.000001257 | <1 us | 2020 | IT=100% |
| 203Tln | 202.972344098 ± 0.000001257 | 7.7 us ± 0.5 | 1998 | IT=100% |
| 204Tl | 203.973863420 ± 0.000001238 | 3.783 y ± 0.012 | 1953 | β-=97.08±0.7%; ε+β+=2.92±0.7% |
| 204Tlm | 203.973863420 ± 0.000001238 | 61.7 us ± 1.0 | 1972 | IT=100% |
| 204Tln | 203.973863420 ± 0.000001238 | 2.6 us ± 0.2 | 1998 | IT=100% |
| 204Tlp | 203.973863420 ± 0.000001238 | 420 ns ± 30 | 1998 | IT=100% |
| 204Tlq | 203.973863420 ± 0.000001238 | 90 ns ± 3 | 2011 | IT=100% |
| 205Tl | 204.974427318 ± 0.00000133 | Stable | 1931 | IS=70.485±4.4% |
| 205Tlm | 204.974427318 ± 0.00000133 | 2.6 us ± 0.2 | 1976 | IT=100% |
| 205Tln | 204.974427318 ± 0.00000133 | 235 ns ± 10 | 2004 | IT=100% |
| 206Tl | 205.976110108 ± 0.00000138 | 4.202 m ± 0.011 | 1935 | β-=100% |
| 206Tlm | 205.976110108 ± 0.00000138 | 3.74 m ± 0.03 | 1976 | IT=100% |
| 207Tl | 206.977418605 ± 0.000005839 | 4.77 m ± 0.02 | 1908 | β-=100% |
| 207Tlm | 206.977418605 ± 0.000005839 | 1.33 s ± 0.11 | 1965 | IT≈100%; β- ? |
| 208Tl | 207.982018006 ± 0.000001989 | 3.053 m ± 0.004 | 1909 | β-=100% |
| 208Tlm | 207.982018006 ± 0.000001989 | 1.3 us ± 0.1 | 2020 | IT=100% |
| 209Tl | 208.985351713 ± 0.000006559 | 2.162 m ± 0.007 | 1950 | β-=100%; β-n ? |
| 209Tlm | 208.985351713 ± 0.000006559 | 146 ns ± 10 | 2009 | IT=100% |
| 210Tl | 209.990072942 ± 0.000012456 | 1.30 m ± 0.03 | 1909 | β-=100%; β-n=0.009±0.6% |
| 210Tlm | 209.990072942 ± 0.000012456 | 1 m >3 us [Estimated] | 2018 | β- ?; IT ? |
| 211Tl | 210.993475000 ± 0.000045 | 81 s ± 16 | 1998 | β-=100%; β-n=2.2±2.2% |
| 211Tlm | 210.993475000 ± 0.000045 | 580 ns ± 80 | 2019 | IT=100% |
| 212Tl | 211.998335 ± 0.000215 [Estimated] | 31 s ± 8 | 1998 | β-=100%; β-n=1.8±1.8% |
| 213Tl | 213.001915000 ± 0.000029 | 23.8 s ± 4.4 | 2010 | β-=100%; β-n=7.6±3.4% |
| 213Tlm | 213.001915000 ± 0.000029 | 4.1 us ± 0.5 | 2019 | IT=100% |
| 213Tln | 213.001915000 ± 0.000029 | 0.6 us ± 0.3 | 2019 | IT=100% |
| 214Tl | 214.006940 ± 0.00021 [Estimated] | 11.0 s ± 2.4 | 2010 | β-=100%; β-n=34±1.2% |
| 215Tl | 215.010768 ± 0.000322 [Estimated] | 9.7 s ± 3.8 | 2010 | β-=100%; β-n=4.6±4.6% |
| 216Tl | 216.015964 ± 0.000322 [Estimated] | 5.9 s ± 3.3 | 2010 | β-=100%; β-n<11.5% |
| 217Tl | 217.020032 ± 0.000429 [Estimated] | 2 s >300ns [Estimated] | 2010 | β- ?; β-n ? |
| 218Tl | 218.025454 ± 0.000429 [Estimated] | 1 s [Estimated] | β- ?; β-n ? |
