Thallium Thallium is a chemical element; it has Symbol (chemistry), symbol Tl and atomic number 81. It is a silvery-white post-transition metal that is not found free in nature. When isolated, thallium resembles tin, but discolors when exposed to air. Che ...

(₈₁Tl) has 42

isotope Isotopes are distinct nuclear species (or ''nuclides'') of the same chemical element. They have the same atomic number (number of protons in their Atomic nucleus, nuclei) and position in the periodic table (and hence belong to the same chemica ...

s with

atomic mass Atomic mass ( or ) is the mass of a single atom. The atomic mass mostly comes from the combined mass of the protons and neutrons in the nucleus, with minor contributions from the electrons and nuclear binding energy. The atomic mass of atoms, ...

es that range from 176 to 217. ²⁰³Tl and ²⁰⁵Tl are the only stable isotopes and ²⁰⁴Tl is the most stable

radioisotope A radionuclide (radioactive nuclide, radioisotope or radioactive isotope) is a nuclide that has excess numbers of either neutrons or protons, giving it excess nuclear energy, and making it unstable. This excess energy can be used in one of three ...

with a

half-life Half-life is a mathematical and scientific description of exponential or gradual decay. Half-life, half life or halflife may also refer to: Film * Half-Life (film), ''Half-Life'' (film), a 2008 independent film by Jennifer Phang * ''Half Life: ...

of 3.78 years. ²⁰⁷Tl, with a half-life of 4.77 minutes, has the longest half-life of naturally occurring Tl radioisotopes. All isotopes of thallium are either radioactive or

observationally stable Stable nuclides are isotopes of a chemical element whose nucleons are in a configuration that does not permit them the surplus energy required to produce a radioactive emission. The nuclei of such isotopes are not radioactive and unlike radionuc ...

, meaning that they are predicted to be radioactive but no actual decay has been observed. Thallium-202 (half-life 12.23 days) can be made in a cyclotron while thallium-204 (half-life 3.78 years) is made by the

neutron activation Neutron activation is the process in which neutron radiation induces radioactivity in materials, and occurs when atomic nuclei capture free neutrons, becoming heavier and entering excited states. The excited nucleus decays immediately by emi ...

of stable thallium in a

nuclear reactor A nuclear reactor is a device used to initiate and control a Nuclear fission, fission nuclear chain reaction. They are used for Nuclear power, commercial electricity, nuclear marine propulsion, marine propulsion, Weapons-grade plutonium, weapons ...

. In the fully ionized state, the isotope ²⁰⁵Tl⁸¹⁺ becomes beta-radioactive, undergoing bound-state β⁻ decay to ²⁰⁵Pb⁸¹⁺ with a half-life of days, but ²⁰³Tl remains stable. ²⁰⁵Tl is the decay product of

bismuth-209 Bismuth-209 (Bi) is an isotope of bismuth, with the longest known half-life of any radioisotope that undergoes α-decay (alpha decay). It has 83 protons and a magic number of 126 neutrons, and an atomic mass of 208.9803987 amu (atomic mass unit ...

, an isotope that was once thought to be stable but is now known to undergo

alpha decay Alpha decay or α-decay is a type of radioactive decay in which an atomic nucleus emits an alpha particle (helium nucleus). The parent nucleus transforms or "decays" into a daughter product, with a mass number that is reduced by four and an a ...

with an extremely long half-life of 2.01×10¹⁹ y. ²⁰⁵Tl is at the end of the

neptunium Neptunium is a chemical element; it has chemical symbol, symbol Np and atomic number 93. A radioactivity, radioactive actinide metal, neptunium is the first transuranic element. It is named after Neptune, the planet beyond Uranus in the Solar Syste ...

series Series may refer to: People with the name * Caroline Series (born 1951), English mathematician, daughter of George Series * George Series (1920–1995), English physicist Arts, entertainment, and media Music * Series, the ordered sets used i ...

decay chain.

List of isotopes

, -id=Thallium-176 , rowspan=2, ¹⁷⁶Tl , rowspan=2, , rowspan=2 style="text-align:right" , 81 , rowspan=2 style="text-align:right" , 95 , rowspan=2, 176.000628(89) , rowspan=2, , p (50%) , ¹⁷⁵Hg , rowspan=2, (3−,4−) , rowspan=2, , rowspan=2, , - , α (50%) , ¹⁷²Au , -id=Thallium-176m , rowspan=2 style="text-indent:1em" , ^176mTl , rowspan=2, , rowspan=2 colspan="3" style="text-indent:2em" , 671 keV , rowspan=2, , p (50%) , ¹⁷⁵Hg , rowspan=2, , rowspan=2, , rowspan=2, , - , α (50%) , ^172mAu , -id=Thallium-177 , rowspan=2, ¹⁷⁷Tl , rowspan=2, , rowspan=2 style="text-align:right" , 81 , rowspan=2 style="text-align:right" , 96 , rowspan=2, 176.996414(23) , rowspan=2, 18(5) ms , α (73%) , ¹⁷³Au , rowspan=2, (1/2+) , rowspan=2, , rowspan=2, , - , p (27%) , ¹⁷⁶Hg , -id=Thallium-177m , rowspan=2 style="text-indent:1em" , ^177mTl , rowspan=2, , rowspan=2 colspan="3" style="text-indent:2em" , 807(18) keV , rowspan=2, 230(40) μs , p (51%) , ¹⁷⁶Hg , rowspan=2, (11/2−) , rowspan=2, , rowspan=2, , - , α (49%) , ¹⁷³Au , -id=Thallium-178 , rowspan=3, ¹⁷⁸Tl , rowspan=3, , rowspan=3 style="text-align:right" , 81 , rowspan=3 style="text-align:right" , 97 , rowspan=3, 177.99505(11)# , rowspan=3, 255(9) ms , α (62%) , ¹⁷⁴Au , rowspan=3, (4-,5-) , rowspan=3, , rowspan=3, , - , β⁺ (38%) , ¹⁷⁸Hg , - , β⁺, SF (0.15%) , (various) , -id=Thallium-179 , rowspan=2, ¹⁷⁹Tl , rowspan=2, , rowspan=2 style="text-align:right" , 81 , rowspan=2 style="text-align:right" , 98 , rowspan=2, 178.991122(41) , rowspan=2, 437(9) ms , α (60%) , ¹⁷⁵Au , rowspan=2, 1/2+ , rowspan=2, , rowspan=2, , - , β⁺ (40%) , ¹⁷⁹Hg , -id=Thallium-179m1 , style="text-indent:1em" , ^179m1Tl , , colspan="3" style="text-indent:2em" , 825(10)# keV , 1.41(2) ms , α , ¹⁷⁵Au , (11/2−) , , , -id=Thallium-179m2 , style="text-indent:1em" , ^179m2Tl , , colspan="3" style="text-indent:2em" , 904.5(9) keV , 119(14) ns , IT , ¹⁷⁹Tl , (9/2−) , , , -id=Thallium-180 , rowspan=3, ¹⁸⁰Tl , rowspan=3, , rowspan=3 style="text-align:right" , 81 , rowspan=3 style="text-align:right" , 99 , rowspan=3, 179.989919(75) , rowspan=3, 1.09(1) s , β⁺ (93%) , ¹⁸⁰Hg , rowspan=3, (4-) , rowspan=3, , rowspan=3, , - , α (7%) , ¹⁷⁶Au , - , β⁺, SF (0.0032%) , ¹⁰⁰Ru, ⁸⁰Kr , -id=Thallium-181 , rowspan=2, ¹⁸¹Tl , rowspan=2, , rowspan=2 style="text-align:right" , 81 , rowspan=2 style="text-align:right" , 100 , rowspan=2, 180.9862600(98) , rowspan=2, 2.9(1) s , β⁺ (91.4%) , ¹⁸¹Hg , rowspan=2, 1/2+ , rowspan=2, , rowspan=2, , - , α (8.6%) , ¹⁷⁷Au , -id=Thallium-181m , rowspan=2 style="text-indent:1em" , ^181mTl , rowspan=2, , rowspan=2 colspan="3" style="text-indent:2em" , 835.9(4) keV , rowspan=2, 1.40(3) ms , IT (99.60%) , ¹⁸¹Tl , rowspan=2, (9/2−) , rowspan=2, , rowspan=2, , - , α (0.40%) , ¹⁷⁷Au , -id=Thallium-182 , rowspan=3, ¹⁸²Tl , rowspan=3, , rowspan=3 style="text-align:right" , 81 , rowspan=3 style="text-align:right" , 101 , rowspan=3, 181.985693(13) , rowspan=3, 1.9(1) s , β⁺ (<99.41%) , ¹⁸²Hg , rowspan=3, (4−) , rowspan=3, , rowspan=3, , - , α (>0.49%) , ¹⁷⁸Au , - , β⁺, SF (<3.4%) , ¹⁸²Hg , -id=Thallium-182m , rowspan=2 style="text-indent:1em" , ^182mTlOrder of ground state and isomer is uncertain. , rowspan=2, , rowspan=2 colspan="3" style="text-indent:2em" , 50(50)# keV , rowspan=2, 3.1(10) s , β⁺ (97.5%) , ¹⁸²Hg , rowspan=2, (7+) , rowspan=2, , rowspan=2, , - , α (2.5%) , ¹⁷⁸Au , -id=Thallium-183 , rowspan=2, ¹⁸³Tl , rowspan=2, , rowspan=2 style="text-align:right" , 81 , rowspan=2 style="text-align:right" , 102 , rowspan=2, 182.982193(10) , rowspan=2, 6.9(7) s , β⁺ (?%) , ¹⁸³Hg , rowspan=2, 1/2+ , rowspan=2, , rowspan=2, , - , α (?%) , ¹⁷⁹Au , -id=Thallium-183m1 , rowspan=3 style="text-indent:1em" , ^183m1Tl , rowspan=3, , rowspan=3 colspan="3" style="text-indent:2em" , 628.7(5) keV , rowspan=3, 53.3(3) ms , IT (?%) , ¹⁸³Tl , rowspan=3, (9/2−) , rowspan=3, , rowspan=3, , - , α (1.5%) , ¹⁷⁹Au , - , β⁺ (?%) , ¹⁸³Hg , -id=Thallium-183m2 , style="text-indent:1em" , ^183m2Tl , , colspan="3" style="text-indent:2em" , 975.3(6) keV , 1.48(10) μs , IT , ¹⁸³Tl , (13/2+) , , , -id=Thallium-184 , rowspan=2, ¹⁸⁴Tl , rowspan=2, , rowspan=2 style="text-align:right" , 81 , rowspan=2 style="text-align:right" , 103 , rowspan=2, 183.981875(11) , rowspan=2, 9.5(2) s , β⁺ (98.78%) , ¹⁸⁴Hg , rowspan=2, 2− , rowspan=2, , rowspan=2, , - , α (1.22%) , ¹⁸⁰Au , -id=Thallium-184m1 , rowspan=2 style="text-indent:1em" , ^184m1Tl , rowspan=2, , rowspan=2 colspan="3" style="text-indent:2em" , −50(30) keV , rowspan=2, 10.6(5) s , β⁺ (99.53%) , ¹⁸⁴Hg , rowspan=2, (7+) , rowspan=2, , rowspan=2, , - , α (0.47%) , ¹⁸⁰Au , -id=Thallium-184m2 , rowspan=2 style="text-indent:1em" , ^184m2Tl , rowspan=2, , rowspan=2 colspan="3" style="text-indent:2em" , 450(30) keV , rowspan=2, 47.1(7) ms , IT (99.91%) , , rowspan=2, (10−) , rowspan=2, , rowspan=2, , - , α (0.089%) , ¹⁸⁰Au , -id=Thallium-185 , ¹⁸⁵Tl , , style="text-align:right" , 81 , style="text-align:right" , 104 , 184.978789(22) , 19.5(5) s , β⁺ , ¹⁸⁵Hg , 1/2+ , , , - , -id=Thallium-185m , rowspan=2 style="text-indent:1em" , ^185mTl , rowspan=2, , rowspan=2 colspan="3" style="text-indent:2em" , 454.8(15) keV , rowspan=2, 1.93(8) s , IT , ¹⁸⁵Tl , rowspan=2, 9/2− , rowspan=2, , rowspan=2, , - , α (?%) , ¹⁸¹Au , -id=Thallium-186 , rowspan=2, ¹⁸⁶Tl , rowspan=2, , rowspan=2 style="text-align:right" , 81 , rowspan=2 style="text-align:right" , 105 , rowspan=2, 185.978655(22) , rowspan=2, 3.5(5) s , β⁺ (?%) , ¹⁸⁶Hg , rowspan=2, (2−) , rowspan=2, , rowspan=2, , - , α (?%) , ¹⁸²Au , -id=Thallium-186m1 , rowspan=2 style="text-indent:1em" , ^186m1Tl , rowspan=2, , rowspan=2 colspan="3" style="text-indent:2em" , 20(40) keV , rowspan=2, 27.5(10) s , β⁺ (99.99%) , ¹⁸⁶Hg , rowspan=2, 7+ , rowspan=2, , rowspan=2, , - , α (0.006%) , ¹⁸²Au , -id=Thallium-186m2 , rowspan=2 style="text-indent:1em" , ^186m2Tl , rowspan=2, , rowspan=2 colspan="3" style="text-indent:2em" , 390(40) keV , rowspan=2, 3.40(9) s , IT (<94.1%) , ¹⁸⁶Tl , rowspan=2, 10− , rowspan=2, , rowspan=2, , - , β⁺ (>5.9%) , ¹⁸⁶Hg , -id=Thallium-187 , ¹⁸⁷Tl , , style="text-align:right" , 81 , style="text-align:right" , 106 , 186.9759047(86) , ~51 s , β⁺ , ¹⁸⁷Hg , 1/2+ , , , -id=Thallium-187m1 , rowspan=3 style="text-indent:1em" , ^187m1Tl , rowspan=3, , rowspan=3 colspan="3" style="text-indent:2em" , 334(3) keV , rowspan=3, 15.60(12) s , β⁺ (?%) , ¹⁸⁷Hg , rowspan=3, 9/2− , rowspan=3, , rowspan=3, , - , IT (?%) , ¹⁸⁷Tl , - , α (0.15%) , ¹⁸³Au , -id=Thallium-187m2 , style="text-indent:1em" , ^187m2Tl , , colspan="3" style="text-indent:2em" , 1875(50)# keV , 1.11(7) μs , IT , ¹⁸⁷Tl , , , , -id=Thallium-187m3 , style="text-indent:1em" , ^187m3Tl , , colspan="3" style="text-indent:2em" , 2582.5(3) keV , 693(38) ns , IT , ¹⁸⁷Tl , 29/2+# , , , -id=Thallium-188 , ¹⁸⁸Tl , , style="text-align:right" , 81 , style="text-align:right" , 107 , 187.976021(32) , 71(2) s , β⁺ , ¹⁸⁸Hg , 2−# , , , -id=Thallium-188m1 , style="text-indent:1em" , ^188m1Tl , , colspan="3" style="text-indent:2em" , 30(30) keV , 71.5(15) s , β⁺ , ¹⁸⁸Hg , 7+ , , , -id=Thallium-188m2 , style="text-indent:1em" , ^188m2Tl , , colspan="3" style="text-indent:2em" , 299(30) keV , 41(4) ms , IT , ¹⁸⁸Tl , 9− , , , -id=Thallium-189 , ¹⁸⁹Tl , , style="text-align:right" , 81 , style="text-align:right" , 108 , 188.9735735(90) , 2.3(2) min , β⁺ , ¹⁸⁹Hg , 1/2+ , , , -id=Thallium-189m , style="text-indent:1em" , ^189mTl , , colspan="3" style="text-indent:2em" , 285(6) keV , 1.4(1) min , β⁺ , ¹⁸⁹Hg , 9/2− , , , -id=Thallium-190 , ¹⁹⁰Tl , , style="text-align:right" , 81 , style="text-align:right" , 109 , 189.9738418(78) , 2.6(3) min , β⁺ , ¹⁹⁰Hg , 2− , , , -id=Thallium-190m1 , style="text-indent:1em" , ^190m1Tl , , colspan="3" style="text-indent:2em" , 70(7) keV , 3.6(3) min , β⁺ , ¹⁹⁰Hg , 7+ , , , -id=Thallium-190m2 , style="text-indent:1em" , ^190m2Tl , , colspan="3" style="text-indent:2em" , 306(10) keV , 60# ms , IT , ¹⁹⁰Tl , (9−) , , , -id=Thallium-191 , ¹⁹¹Tl , , style="text-align:right" , 81 , style="text-align:right" , 110 , 190.9717841(79) , 20# min , β⁺ , ¹⁹¹Hg , 1/2+ , , , -id=Thallium-191m , style="text-indent:1em" , ^191mTl , , colspan="3" style="text-indent:2em" , 297(7) keV , 5.22(16) min , β⁺ , ¹⁹¹Hg , 9/2− , , , -id=Thallium-192 , ¹⁹²Tl , , style="text-align:right" , 81 , style="text-align:right" , 111 , 191.972225(34) , 9.6(4) min , β⁺ , ¹⁹²Hg , 2− , , , -id=Thallium-192m1 , style="text-indent:1em" , ^192m1Tl , , colspan="3" style="text-indent:2em" , 196(7) keV , 10.8(2) min , β⁺ , ¹⁹²Hg , 7+ , , , -id=Thallium-192m2 , style="text-indent:1em" , ^192m2Tl , , colspan="3" style="text-indent:2em" , 447(7) keV , 296(5) ns , IT , ¹⁹²Tl , (8−) , , , -id=Thallium-192m3 , style="text-indent:1em" , ^192m3Tl , , colspan="3" style="text-indent:2em" , 180(40) keV , , α , ¹⁸⁸Au , (3+) , , , -id=Thallium-193 , ¹⁹³Tl , , style="text-align:right" , 81 , style="text-align:right" , 112 , 192.9705020(72) , 21.6(8) min , β⁺ , ¹⁹³Hg , 1/2+ , , , -id=Thallium-193m , rowspan=2 style="text-indent:1em" , ^193mTl , rowspan=2, , rowspan=2 colspan="3" style="text-indent:2em" , 372(4) keV , rowspan=2, 2.11(15) min , IT (~75%) , ¹⁹³Tl , rowspan=2, 9/2− , rowspan=2, , rowspan=2, , - , β⁺ (~25%) , ¹⁹³Hg , -id=Thallium-194 , ¹⁹⁴Tl , , style="text-align:right" , 81 , style="text-align:right" , 113 , 193.971081(15) , 33.0(5) min , β⁺ , ¹⁹⁴Hg , 2− , , , -id=Thallium-194m , style="text-indent:1em" , ^194mTl , , colspan="3" style="text-indent:2em" , 260(14) keV , 32.8(2) min , β⁺ , ¹⁹⁴Hg , 7+ , , , -id=Thallium-195 , ¹⁹⁵Tl , , style="text-align:right" , 81 , style="text-align:right" , 114 , 194.969774(12) , 1.16(5) h , β⁺ , ¹⁹⁵Hg , 1/2+ , , , -id=Thallium-195m , style="text-indent:1em" , ^195mTl , , colspan="3" style="text-indent:2em" , 482.63(17) keV , 3.6(4) s , IT , ¹⁹⁵Tl , 9/2− , , , -id=Thallium-196 , ¹⁹⁶Tl , , style="text-align:right" , 81 , style="text-align:right" , 115 , 195.970481(13) , 1.84(3) h , β⁺ , ¹⁹⁶Hg , 2− , , , -id=Thallium-196m , rowspan=2 style="text-indent:1em" , ^196mTl , rowspan=2, , rowspan=2 colspan="3" style="text-indent:2em" , 394.2(5) keV , rowspan=2, 1.41(2) h , β⁺ (96.2%) , ¹⁹⁶Hg , rowspan=2, 7+ , rowspan=2, , rowspan=2, , - , IT (3.8%) , ¹⁹⁶Tl , -id=Thallium-197 , ¹⁹⁷Tl , , style="text-align:right" , 81 , style="text-align:right" , 116 , 196.969560(15) , 2.84(4) h , β⁺ , ¹⁹⁷Hg , 1/2+ , , , -id=Thallium-197m , style="text-indent:1em" , ^197mTl , , colspan="3" style="text-indent:2em" , 608.22(8) keV , 540(10) ms , IT , ¹⁹⁷Tl , 9/2− , , , -id=Thallium-198 , ¹⁹⁸Tl , , style="text-align:right" , 81 , style="text-align:right" , 117 , 197.9704467(81) , 5.3(5) h , β⁺ , ¹⁹⁸Hg , 2− , , , -id=Thallium-198m1 , rowspan=2 style="text-indent:1em" , ^198m1Tl , rowspan=2, , rowspan=2 colspan="3" style="text-indent:2em" , 543.6(4) keV , rowspan=2, 1.87(3) h , β⁺ (55.9%) , ¹⁹⁸Hg , rowspan=2, 7+ , rowspan=2, , rowspan=2, , - , IT (44.1%) , ¹⁹⁸Tl , -id=Thallium-198m2 , style="text-indent:1em" , ^198m2Tl , , colspan="3" style="text-indent:2em" , 686.8(5) keV , 150(40) ns , IT , ¹⁹⁸Tl , (5)+ , , , -id=Thallium-198m3 , style="text-indent:1em" , ^198m3Tl , , colspan="3" style="text-indent:2em" , 742.4(4) keV , 32.1(10) ms , IT , ¹⁹⁸Tl , 10− , , , -id=Thallium-199 , ¹⁹⁹Tl , , style="text-align:right" , 81 , style="text-align:right" , 118 , 198.969877(30) , 7.42(8) h , β⁺ , ¹⁹⁹Hg , 1/2+ , , , -id=Thallium-199m , style="text-indent:1em" , ^199mTl , , colspan="3" style="text-indent:2em" , 748.87(6) keV , 28.4(2) ms , IT , ¹⁹⁹Tl , 9/2− , , , -id=Thallium-200 , ²⁰⁰Tl , , style="text-align:right" , 81 , style="text-align:right" , 119 , 199.9709636(62) , 26.1(1) h , β⁺ , ²⁰⁰Hg , 2− , , , -id=Thallium-200m1 , style="text-indent:1em" , ^200m1Tl , , colspan="3" style="text-indent:2em" , 753.60(24) keV , 34.0(9) ms , IT , ²⁰⁰Tl , 7+ , , , -id=Thallium-200m2 , style="text-indent:1em" , ^200m2Tl , , colspan="3" style="text-indent:2em" , 762.00(24) keV , 397(17) ns , IT , ²⁰⁰Tl , 5+ , , , - , ²⁰¹TlMain isotope used in

scintigraphy Scintigraphy (from Latin ''scintilla'', "spark"), also known as a gamma scan, is a diagnostic test in nuclear medicine, where radioisotopes attached to drugs that travel to a specific organ or tissue (radiopharmaceuticals) are taken internally a ...

, , style="text-align:right" , 81 , style="text-align:right" , 120 , 200.970820(15) , 3.0421(8) d , EC , ²⁰¹Hg , 1/2+ , , , -id=Thallium-201m , style="text-indent:1em" , ^201mTl , , colspan="3" style="text-indent:2em" , 919.16(21) keV , 2.01(7) ms , IT , ²⁰¹Tl , 9/2− , , , -id=Thallium-202 , ²⁰²Tl , , style="text-align:right" , 81 , style="text-align:right" , 121 , 201.9721089(20) , 12.31(8) d , EC , ²⁰²Hg , 2− , , , -id=Thallium-202m , style="text-indent:1em" , ^202mTl , , colspan="3" style="text-indent:2em" , 950.19(10) keV , 591(3) μs , IT , ²⁰²Tl , 7+ , , , -id=Thallium-203 , ²⁰³Tl , , style="text-align:right" , 81 , style="text-align:right" , 122 , 202.9723441(13) , colspan=3 align=center,

Observationally Stable Stable nuclides are isotopes of a chemical element whose nucleons are in a configuration that does not permit them the surplus energy required to produce a radioactive emission. The nuclei of such isotopes are not radioactive and unlike radionuc ...

Believed to undergo α decay to ¹⁹⁹Au , 1/2+ , 0.29515(44) , , -id=Thallium-203m1 , style="text-indent:1em" , ^203m1Tl , , colspan="3" style="text-indent:2em" , 1483.7(9) keV , <1 μs , IT , ²⁰³Tl , (9/2−) , , , -id=Thallium-203m2 , style="text-indent:1em" , ^203m2Tl , , colspan="3" style="text-indent:2em" , 3565(50)# keV , 7.7(5) μs , IT , ²⁰³Tl , (25/2+) , , , -id=Thallium-204 , rowspan=2, ²⁰⁴Tl , rowspan=2, , rowspan=2 style="text-align:right" , 81 , rowspan=2 style="text-align:right" , 123 , rowspan=2, 203.9738634(12) , rowspan=2, 3.783(12) y , β⁻ (97.08%) , ²⁰⁴Pb , rowspan=2, 2− , rowspan=2, , rowspan=2, , - , EC (2.92%) , ²⁰⁴Hg , -id=Thallium-204m1 , style="text-indent:1em" , ^204m1Tl , , colspan="3" style="text-indent:2em" , 1104.1(2) keV , 61.7(10) μs , IT , ²⁰⁴Tl , 7+ , , , -id=Thallium-204m2 , style="text-indent:1em" , ^204m2Tl , , colspan="3" style="text-indent:2em" , 2319.0(3) keV , 2.6(2) μs , IT , ²⁰⁴Tl , 12− , , , -id=Thallium-204m3 , style="text-indent:1em" , ^204m3Tl , , colspan="3" style="text-indent:2em" , 4391.6(5) keV , 420(30) ns , IT , ²⁰⁴Tl , 18+ , , , -id=Thallium-204m4 , style="text-indent:1em" , ^204m4Tl , , colspan="3" style="text-indent:2em" , 6239.4(5) keV , 90(3) ns , IT , ²⁰⁴Tl , 22− , , , -id=Thallium-205 , ²⁰⁵TlFinal decay product of 4n+1

decay chain In nuclear science a decay chain refers to the predictable series of radioactive disintegrations undergone by the nuclei of certain unstable chemical elements. Radioactive isotopes do not usually decay directly to stable isotopes, but rather ...

(the

Neptunium series In nuclear science a decay chain refers to the predictable series of radioactive decay, radioactive disintegrations undergone by the nuclei of certain unstable chemical elements. Radionuclide, Radioactive isotopes do not usually decay directly ...

) , , style="text-align:right" , 81 , style="text-align:right" , 124 , 204.9744273(13) , colspan=3 align=center, Observationally StableBelieved to undergo α decay to ²⁰¹Au , 1/2+ , 0.70485(44) , , -id=Thallium-205m1 , style="text-indent:1em" , ^205m1Tl , , colspan="3" style="text-indent:2em" , 3290.61(17) keV , 2.6(2) μs , IT , ²⁰⁵Tl , 25/2+ , , , -id=Thallium-205m2 , style="text-indent:1em" , ^205m2Tl , , colspan="3" style="text-indent:2em" , 4835.6(15) keV , 235(10) ns , IT , ²⁰⁵Tl , (35/2–) , , , -id=Thallium-206 , ²⁰⁶Tl , Radium E" , style="text-align:right" , 81 , style="text-align:right" , 125 , 205.9761101(14) , 4.202(11) min , β⁻ , ²⁰⁶Pb , 0− , TraceIntermediate

decay product In nuclear physics, a decay product (also known as a daughter product, daughter isotope, radio-daughter, or daughter nuclide) is the remaining nuclide left over from radioactive decay. Radioactive decay often proceeds via a sequence of steps ( d ...

of ²³⁸U , , -id=Thallium-206m , style="text-indent:1em" , ^206mTl , , colspan="3" style="text-indent:2em" , 2643.10(18) keV , 3.74(3) min , IT , ²⁰⁶Tl , (12)– , , , -id=Thallium-207 , ²⁰⁷Tl , Actinium C" , style="text-align:right" , 81 , style="text-align:right" , 126 , 206.9774186(58) , 4.77(2) min , β⁻ , ²⁰⁷Pb , 1/2+ , TraceIntermediate

of ²³⁵U , , -id=Thallium-207m , style="text-indent:1em" , ^207mTl , , colspan="3" style="text-indent:2em" , 1348.18(16) keV , 1.33(11) s , IT , ²⁰⁷Tl , 11/2– , , , -id=Thallium-208 , ²⁰⁸Tl , Thorium C" , style="text-align:right" , 81 , style="text-align:right" , 127 , 207.9820180(20) , 3.053(4) min , β⁻ , ²⁰⁸Pb , 5+ , TraceIntermediate

of ²³²Th , , -id=Thallium-208m , style="text-indent:1em" , ^208mTl , , colspan="3" style="text-indent:2em" , 1807(1) keV , 1.3(1) μs , IT , ²⁰⁸Tl , (0–) , , , -id=Thallium-209 , ²⁰⁹Tl , , style="text-align:right" , 81 , style="text-align:right" , 128 , 208.9853517(66) , 2.162(7) min , β⁻ , ²⁰⁹Pb , 1/2+ , TraceIntermediate decay product of ²³⁷Np , , -id=Thallium-209m , style="text-indent:1em" , ^209mTl , , colspan="3" style="text-indent:2em" , 1228.1(20) keV , 146(10) ns , IT , ²⁰⁹Tl , 17/2+ , , , -id=Thallium-210 , rowspan=2, ²¹⁰Tl , rowspan=2, Radium C″ , rowspan=2 style="text-align:right" , 81 , rowspan=2 style="text-align:right" , 129 , rowspan=2, 209.990073(12) , rowspan=2, 1.30(3) min , β⁻ (99.99%) , ²¹⁰Pb , rowspan=2, 5+# , rowspan=2, Trace , rowspan=2, , - , β⁻, n (0.009%) , ²⁰⁹Pb , -id=Thallium-210m , style="text-indent:1em" , ^210mTl , , colspan="3" style="text-indent:2em" , 1200(200)# keV , 1# min
3 μs, , , (9+,10+) , , , -id=Thallium-211 , rowspan=2, ²¹¹Tl , rowspan=2, , rowspan=2 style="text-align:right" , 81 , rowspan=2 style="text-align:right" , 130 , rowspan=2, 210.993475(45) , rowspan=2, 81(16) s , β⁻ (97.8%) , ²¹¹Pb , rowspan=2, 1/2+ , rowspan=2, , rowspan=2, , - , β⁻, n (2.2%) , ²¹⁰Pb , -id=Thallium-211m , style="text-indent:1em" , ^211mTl , , colspan="3" style="text-indent:2em" , 1244(100)# keV , 580(80) ns , IT , ²¹¹Tl , 17/2+# , , , -id=Thallium-212 , rowspan=2, ²¹²Tl , rowspan=2, , rowspan=2 style="text-align:right" , 81 , rowspan=2 style="text-align:right" , 131 , rowspan=2, 211.99834(22)# , rowspan=2, 31(8) s , β⁻ (98.2%) , ²¹²Pb , rowspan=2, (5+) , rowspan=2, , rowspan=2, , - , β⁻, n (1.8%) , ²¹¹Pb , -id=Thallium-213 , rowspan=2, ²¹³Tl , rowspan=2, , rowspan=2 style="text-align:right" , 81 , rowspan=2 style="text-align:right" , 132 , rowspan=2, 213.001915(29) , rowspan=2, 23.8(44) s , β⁻ (92.4%) , ²¹³Pb , rowspan=2, 1/2+# , rowspan=2, , rowspan=2, , - , β⁻, n (7.6%) , ²¹²Pb , -id=Thallium-213m1 , style="text-indent:1em" , ^213m1Tl , , colspan="3" style="text-indent:2em" , 680(300)# keV , 4.1(5) μs , IT , ²¹³Tl , , , , -id=Thallium-213m2 , style="text-indent:1em" , ^213m2Tl , , colspan="3" style="text-indent:2em" , 1250(100)# keV , 0.6(3) μs , IT , ²¹³Tl , 17/2+# , , , -id=Thallium-214 , rowspan=2, ²¹⁴Tl , rowspan=2, , rowspan=2 style="text-align:right" , 81 , rowspan=2 style="text-align:right" , 133 , rowspan=2, 214.00694(21)# , rowspan=2, 11.0(24) s , β⁻ (66%) , ²¹⁴Pb , rowspan=2, 5+# , rowspan=2, , rowspan=2, , - , β⁻, n (34%) , ²¹³Pb , -id=Thallium-215 , rowspan=2, ²¹⁵Tl , rowspan=2, , rowspan=2 style="text-align:right" , 81 , rowspan=2 style="text-align:right" , 134 , rowspan=2, 215.01077(32)# , rowspan=2, 9.7(38) s , β⁻ (95.4%) , ²¹⁵Pb , rowspan=2, 1/2+# , rowspan=2, , rowspan=2, , - , β⁻, n (4.6%) , ²¹⁴Pb , -id=Thallium-216 , rowspan=2, ²¹⁶Tl , rowspan=2, , rowspan=2 style="text-align:right" , 81 , rowspan=2 style="text-align:right" , 135 , rowspan=2, 216.01596(32)# , rowspan=2, 5.9(33) s , β⁻ (>88.5%) , ²¹⁶Pb , rowspan=2, 5+# , rowspan=2, , rowspan=2, , - , β⁻, n (<11.5%) , ²¹⁵Pb , -id=Thallium-217 , ²¹⁷Tl , , style="text-align:right" , 81 , style="text-align:right" , 136 , 217.02003(43)# , 2# s
300 ns, , , 1/2+# , ,

Thallium-201

Thallium-201 (²⁰¹Tl) is a

synthetic radioisotope A synthetic radioisotope is a radionuclide that is not found in nature: no natural process or mechanism exists which produces it, or it is so unstable that it decays away in a very short period of time. Frédéric Joliot-Curie and Irène Joliot-Cu ...

of thallium. It has a half-life of 73 hours and decays by electron capture, emitting X-rays (~70–80 keV), and photons of 135 and 167 keV in 10% total abundance. Thallium-201 is synthesized by the

of stable thallium in a

, or by the ²⁰³Tl(p, 3n)²⁰¹Pb nuclear reaction in

cyclotron A cyclotron is a type of particle accelerator invented by Ernest Lawrence in 1929–1930 at the University of California, Berkeley, and patented in 1932. Lawrence, Ernest O. ''Method and apparatus for the acceleration of ions'', filed: Januar ...

s, as ²⁰¹Pb naturally decays to ²⁰¹Tl afterwards. It is a

radiopharmaceutical Radiopharmaceuticals, or medicinal radiocompounds, are a group of pharmaceutical drugs containing radioactive isotopes. Radiopharmaceuticals can be used as diagnostic and therapeutic agents. Radiopharmaceuticals emit radiation themselves, which ...

, as it has good imaging characteristics without excessive patient radiation dose. It is the most popular isotope used for thallium nuclear

cardiac stress test A cardiac stress test is a cardiological examination that evaluates the cardiovascular system's response to external stress within a controlled clinical setting. This stress response can be induced through physical exercise (usually a treadmill) o ...

References

* Isotope masses from: ** * Isotopic compositions and standard atomic masses from: ** ** * Half-life, spin, and isomer data selected from the following sources. ** ** ** {{Navbox element isotopes Thallium

List of isotopes

Thallium-201

See also

References