Naturally occurring

thulium Thulium is a chemical element with the symbol Tm and atomic number 69. It is the thirteenth and third-last element in the lanthanide series. Like the other lanthanides, the most common oxidation state is +3, seen in its oxide, halides and other c ...

(₆₉Tm) is composed of one stable

isotope Isotopes are two or more types of atoms that have the same atomic number (number of protons in their nuclei) and position in the periodic table (and hence belong to the same chemical element), and that differ in nucleon numbers (mass numb ...

, ¹⁶⁹Tm (100%

natural abundance In physics, natural abundance (NA) refers to the abundance of isotopes of a chemical element as naturally found on a planet. The relative atomic mass (a weighted average, weighted by mole-fraction abundance figures) of these isotopes is the atomi ...

). Thirty-four

radioisotope A radionuclide (radioactive nuclide, radioisotope or radioactive isotope) is a nuclide that has excess nuclear energy, making it unstable. This excess energy can be used in one of three ways: emitted from the nucleus as gamma radiation; transferr ...

s have been characterized, with the most stable being ¹⁷¹Tm with a

half-life Half-life (symbol ) is the time required for a quantity (of substance) to reduce to half of its initial value. The term is commonly used in nuclear physics to describe how quickly unstable atoms undergo radioactive decay or how long stable at ...

of 1.92 years, ¹⁷⁰Tm with a half-life of 128.6 days, ¹⁶⁸Tm with a half-life of 93.1 days, and ¹⁶⁷Tm with a half-life of 9.25 days. All of the remaining

radioactive Radioactive decay (also known as nuclear decay, radioactivity, radioactive disintegration, or nuclear disintegration) is the process by which an unstable atomic nucleus loses energy by radiation. A material containing unstable nuclei is consi ...

isotopes have half-lives that are less than 64 hours, and the majority of these have half-lives that are less than 2 minutes. This element also has 26

meta state A nuclear isomer is a metastable state of an atomic nucleus, in which one or more nucleons (protons or neutrons) occupy higher energy levels than in the ground state of the same nucleus. "Metastable" describes nuclei whose excited states have ...

s, with the most stable being ^164mTm (t_1/2 5.1 minutes), ^160mTm (t_1/2 74.5 seconds) and ^155mTm (t_1/2 45 seconds). The isotopes of thulium range in

atomic weight Relative atomic mass (symbol: ''A''; sometimes abbreviated RAM or r.a.m.), also known by the deprecated synonym atomic weight, is a dimensionless physical quantity defined as the ratio of the average mass of atoms of a chemical element in a giv ...

from 144.97007 u (¹⁴⁵Tm) to 178.95534 u (¹⁷⁹Tm). The primary decay mode before the most abundant stable isotope, ¹⁶⁹Tm, is

electron capture Electron capture (K-electron capture, also K-capture, or L-electron capture, L-capture) is a process in which the proton-rich nucleus of an electrically neutral atom absorbs an inner atomic electron, usually from the K or L electron shells. Thi ...

, and the primary mode after is

beta emission In nuclear physics, beta decay (β-decay) is a type of radioactive decay in which a beta particle (fast energetic electron or positron) is emitted from an atomic nucleus, transforming the original nuclide to an isobar of that nuclide. For exam ...

. The primary decay products before ¹⁶⁹Tm are

erbium Erbium is a chemical element with the symbol Er and atomic number 68. A silvery-white solid metal when artificially isolated, natural erbium is always found in chemical combination with other elements. It is a lanthanide, a rare-earth element, or ...

isotopes, and the primary products after are

ytterbium Ytterbium is a chemical element with the symbol Yb and atomic number 70. It is a metal, the fourteenth and penultimate element in the lanthanide series, which is the basis of the relative stability of its +2 oxidation state. However, like the othe ...

isotopes. All isotopes of thulium are either radioactive or, in the case of ¹⁶⁹Tm,

observationally stable Stable nuclides are nuclides that are not radioactive and so (unlike radionuclides) do not spontaneously undergo radioactive decay. When such nuclides are referred to in relation to specific elements, they are usually termed stable isotopes. Th ...

, meaning that ¹⁶⁹Tm is predicted to be radioactive but no actual decay has been observed.

List of isotopes

, - , ¹⁴⁵Tm , style="text-align:right" , 69 , style="text-align:right" , 76 , 144.97007(43)# , 3.1(3) μs , , , (11/2−) , , , - , rowspan=2, ¹⁴⁶Tm , rowspan=2 style="text-align:right" , 69 , rowspan=2 style="text-align:right" , 77 , rowspan=2, 145.96643(43)# , rowspan=2, 240(30) ms , p , ¹⁴⁵Er , rowspan=2, (6−) , rowspan=2, , rowspan=2, , - , β⁺ (rare) , ¹⁴⁶Er , - , rowspan=2 style="text-indent:1em" , ^146mTm , rowspan=2 colspan="3" style="text-indent:2em" , 71(6) keV , rowspan=2, 72(23) ms , p , ¹⁴⁵Er , rowspan=2, (10+) , rowspan=2, , rowspan=2, , - , β⁺ (rare) , ¹⁴⁶Er , - , rowspan=2, ¹⁴⁷Tm , rowspan=2 style="text-align:right" , 69 , rowspan=2 style="text-align:right" , 78 , rowspan=2, 146.96096(32)# , rowspan=2, 0.58(3) s , β⁺ (85%) , ¹⁴⁷Er , rowspan=2, 11/2− , rowspan=2, , rowspan=2, , - , p (15%) , ¹⁴⁶Er , - , style="text-indent:1em" , ^147mTm , colspan="3" style="text-indent:2em" , 60(5) keV , 360(40) μs , , , 3/2+ , , , - , ¹⁴⁸Tm , style="text-align:right" , 69 , style="text-align:right" , 79 , 147.95784(43)# , 0.7(2) s , β⁺ , ¹⁴⁸Er , (10+) , , , - , style="text-indent:1em" , ^148mTm , colspan="3" style="text-indent:2em" , , 0.7 s , , , , , , - , rowspan=2, ¹⁴⁹Tm , rowspan=2 style="text-align:right" , 69 , rowspan=2 style="text-align:right" , 80 , rowspan=2, 148.95272(32)# , rowspan=2, 0.9(2) s , β⁺ (99.74%) , ¹⁴⁹Er , rowspan=2, (11/2−) , rowspan=2, , rowspan=2, , - , β⁺, p (.26%) , ¹⁴⁸Ho , - , ¹⁵⁰Tm , style="text-align:right" , 69 , style="text-align:right" , 81 , 149.94996(21)# , 3# s , β⁺ , ¹⁵⁰Er , (1+) , , , - , rowspan=2 style="text-indent:1em" , ^150m1Tm , rowspan=2 colspan="3" style="text-indent:2em" , 140(140)# keV , rowspan=2, 2.20(6) s , β⁺ (98.8%) , ¹⁵⁰Er , rowspan=2, (6−) , rowspan=2, , rowspan=2, , - , β⁺, p (1.2%) , ¹⁴⁹Ho , - , style="text-indent:1em" , ^150m2Tm , colspan="3" style="text-indent:2em" , 810(140)# keV , 5.2(3) ms , , , (10+) , , , - , ¹⁵¹Tm , style="text-align:right" , 69 , style="text-align:right" , 82 , 150.945483(22) , 4.17(10) s , β⁺ , ¹⁵¹Er , (11/2−) , , , - , style="text-indent:1em" , ^151m1Tm , colspan="3" style="text-indent:2em" , 92(7) keV , 6.6(14) s , β⁺ , ¹⁵¹Er , (1/2+) , , , - , style="text-indent:1em" , ^151m2Tm , colspan="3" style="text-indent:2em" , 2655.67(22) keV , 451(24) ns , , , (27/2−) , , , - , ¹⁵²Tm , style="text-align:right" , 69 , style="text-align:right" , 83 , 151.94442(8) , 8.0(10) s , β⁺ , ¹⁵²Er , (2#)− , , , - , style="text-indent:1em" , ^152m1Tm , colspan="3" style="text-indent:2em" , 100(80)# keV , 5.2(6) s , β⁺ , ¹⁵²Er , (9)+ , , , - , style="text-indent:1em" , ^152m2Tm , colspan="3" style="text-indent:2em" , 2555.05(19)+X keV , 294(12) ns , , , (17+) , , , - , rowspan=2, ¹⁵³Tm , rowspan=2 style="text-align:right" , 69 , rowspan=2 style="text-align:right" , 84 , rowspan=2, 152.942012(20) , rowspan=2, 1.48(1) s , α (91%) , ¹⁴⁹Ho , rowspan=2, (11/2−) , rowspan=2, , rowspan=2, , - , β⁺ (9%) , ¹⁵³Er , - , rowspan=2 style="text-indent:1em" , ^153mTm , rowspan=2 colspan="3" style="text-indent:2em" , 43.2(2) keV , rowspan=2, 2.5(2) s , α (92%) , ¹⁴⁹Ho , rowspan=2, (1/2+) , rowspan=2, , rowspan=2, , - , β⁺ (8%) , ¹⁵³Er , - , rowspan=2, ¹⁵⁴Tm , rowspan=2 style="text-align:right" , 69 , rowspan=2 style="text-align:right" , 85 , rowspan=2, 153.941568(15) , rowspan=2, 8.1(3) s , β⁺ (56%) , ¹⁵⁴Er , rowspan=2, (2−) , rowspan=2, , rowspan=2, , - , α (44%) , ¹⁵⁰Ho , - , rowspan=2 style="text-indent:1em" , ^154mTm , rowspan=2 colspan="3" style="text-indent:2em" , 70(50) keV , rowspan=2, 3.30(7) s , α (90%) , ¹⁵⁰Ho , rowspan=2, (9+) , rowspan=2, , rowspan=2, , - , β⁺ (10%) , ¹⁵⁴Er , - , rowspan=2, ¹⁵⁵Tm , rowspan=2 style="text-align:right" , 69 , rowspan=2 style="text-align:right" , 86 , rowspan=2, 154.939199(14) , rowspan=2, 21.6(2) s , β⁺ (98.1%) , ¹⁵⁵Er , rowspan=2, (11/2−) , rowspan=2, , rowspan=2, , - , α (1.9%) , ¹⁵¹Ho , - , rowspan=2 style="text-indent:1em" , ^155mTm , rowspan=2 colspan="3" style="text-indent:2em" , 41(6) keV , rowspan=2, 45(3) s , β⁺ (92%) , ¹⁵⁵Er , rowspan=2, (1/2+) , rowspan=2, , rowspan=2, , - , α (8%) , ¹⁵¹Ho , - , rowspan=2, ¹⁵⁶Tm , rowspan=2 style="text-align:right" , 69 , rowspan=2 style="text-align:right" , 87 , rowspan=2, 155.938980(17) , rowspan=2, 83.8(18) s , β⁺ (99.93%) , ¹⁵⁶Er , rowspan=2, 2− , rowspan=2, , rowspan=2, , - , α (.064%) , ¹⁵²Er , - , style="text-indent:1em" , ^156mTm , colspan="3" style="text-indent:2em" , 203.6(5) keV , ~400 ns , , , (11−) , , , - , ¹⁵⁷Tm , style="text-align:right" , 69 , style="text-align:right" , 88 , 156.93697(3) , 3.63(9) min , β⁺ , ¹⁵⁷Er , 1/2+ , , , - , ¹⁵⁸Tm , style="text-align:right" , 69 , style="text-align:right" , 89 , 157.936980(27) , 3.98(6) min , β⁺ , ¹⁵⁸Er , 2− , , , - , style="text-indent:1em" , ^158mTm , colspan="3" style="text-indent:2em" , 50(100)# keV , ~20 ns , , , (5+) , , , - , ¹⁵⁹Tm , style="text-align:right" , 69 , style="text-align:right" , 90 , 158.93498(3) , 9.13(16) min , β⁺ , ¹⁵⁹Er , 5/2+ , , , - , ¹⁶⁰Tm , style="text-align:right" , 69 , style="text-align:right" , 91 , 159.93526(4) , 9.4(3) min , β⁺ , ¹⁶⁰Er , 1− , , , - , rowspan=2 style="text-indent:1em" , ^160m1Tm , rowspan=2 colspan="3" style="text-indent:2em" , 70(20) keV , rowspan=2, 74.5(15) s , IT (85%) , ¹⁶⁰Tm , rowspan=2, 5(+#) , rowspan=2, , rowspan=2, , - , β⁺ (15%) , ¹⁶⁰Er , - , style="text-indent:1em" , ^160m2Tm , colspan="3" style="text-indent:2em" , 98.2+X keV , ~200 ns , , , (8) , , , - , ¹⁶¹Tm , style="text-align:right" , 69 , style="text-align:right" , 92 , 160.93355(3) , 30.2(8) min , β⁺ , ¹⁶¹Er , 7/2+ , , , - , style="text-indent:1em" , ^161m1Tm , colspan="3" style="text-indent:2em" , 7.4(2) keV , 5# min , , , 1/2+ , , , - , style="text-indent:1em" , ^161m2Tm , colspan="3" style="text-indent:2em" , 78.20(3) keV , 110(3) ns , , , 7/2− , , , - , ¹⁶²Tm , style="text-align:right" , 69 , style="text-align:right" , 93 , 161.933995(28) , 21.70(19) min , β⁺ , ¹⁶²Er , 1− , , , - , rowspan=2 style="text-indent:1em" , ^162mTm , rowspan=2 colspan="3" style="text-indent:2em" , 130(40) keV , rowspan=2, 24.3(17) s , IT (82%) , ¹⁶²Tm , rowspan=2, 5+ , rowspan=2, , rowspan=2, , - , β⁺ (18%) , ¹⁶²Er , - , ¹⁶³Tm , style="text-align:right" , 69 , style="text-align:right" , 94 , 162.932651(6) , 1.810(5) h , β⁺ , ¹⁶³Er , 1/2+ , , , - , ¹⁶⁴Tm , style="text-align:right" , 69 , style="text-align:right" , 95 , 163.93356(3) , 2.0(1) min , β⁺ , ¹⁶⁴Er , 1+ , , , - , rowspan=2 style="text-indent:1em" , ^164mTm , rowspan=2 colspan="3" style="text-indent:2em" , 10(6) keV , rowspan=2, 5.1(1) min , IT (80%) , ¹⁶⁴Tm , rowspan=2, 6− , rowspan=2, , rowspan=2, , - , β⁺ (20%) , ¹⁶⁴Er , - , ¹⁶⁵Tm , style="text-align:right" , 69 , style="text-align:right" , 96 , 164.932435(4) , 30.06(3) h , β⁺ , ¹⁶⁵Er , 1/2+ , , , - , ¹⁶⁶Tm , style="text-align:right" , 69 , style="text-align:right" , 97 , 165.933554(13) , 7.70(3) h , β⁺ , ¹⁶⁶Er , 2+ , , , - , style="text-indent:1em" , ^166mTm , colspan="3" style="text-indent:2em" , 122(8) keV , 340(25) ms , IT , ¹⁶⁶Tm , 6− , , , - , ¹⁶⁷Tm , style="text-align:right" , 69 , style="text-align:right" , 98 , 166.9328516(29) , 9.25(2) d , EC , ¹⁶⁷Er , 1/2+ , , , - , style="text-indent:1em" , ^167m1Tm , colspan="3" style="text-indent:2em" , 179.480(19) keV , 1.16(6) μs , , , (7/2)+ , , , - , style="text-indent:1em" , ^167m2Tm , colspan="3" style="text-indent:2em" , 292.820(20) keV , 0.9(1) μs , , , 7/2− , , , - , rowspan=2, ¹⁶⁸Tm , rowspan=2 style="text-align:right" , 69 , rowspan=2 style="text-align:right" , 99 , rowspan=2, 167.934173(3) , rowspan=2, 93.1(2) d , β⁺ (99.99%) , ¹⁶⁸Er , rowspan=2, 3+ , rowspan=2, , rowspan=2, , - , β⁻ (.01%) , ¹⁶⁸Yb , - , ¹⁶⁹Tm , style="text-align:right" , 69 , style="text-align:right" , 100 , 168.9342133(27) , colspan=3 align=center,

Observationally Stable Stable nuclides are nuclides that are not radioactive and so (unlike radionuclides) do not spontaneously undergo radioactive decay. When such nuclides are referred to in relation to specific elements, they are usually termed stable isotopes. Th ...

Believed to undergo α decay to ¹⁶⁵Ho , 1/2+ , 1.0000 , , - , rowspan=2, ¹⁷⁰Tm , rowspan=2 style="text-align:right" , 69 , rowspan=2 style="text-align:right" , 101 , rowspan=2, 169.9358014(27) , rowspan=2, 128.6(3) d , β⁻ (99.86%) , ¹⁷⁰Yb , rowspan=2, 1− , rowspan=2, , rowspan=2, , - , EC (.14%) , ¹⁷⁰Er , - , style="text-indent:1em" , ^170mTm , colspan="3" style="text-indent:2em" , 183.197(4) keV , 4.12(13) μs , , , (3)+ , , , - , ¹⁷¹Tm , style="text-align:right" , 69 , style="text-align:right" , 102 , 170.9364294(28) , 1.92(1) y , β⁻ , ¹⁷¹Yb , 1/2+ , , , - , style="text-indent:1em" , ^171mTm , colspan="3" style="text-indent:2em" , 424.9560(15) keV , 2.60(2) μs , , , 7/2− , , , - , ¹⁷²Tm , style="text-align:right" , 69 , style="text-align:right" , 103 , 171.938400(6) , 63.6(2) h , β⁻ , ¹⁷²Yb , 2− , , , - , ¹⁷³Tm , style="text-align:right" , 69 , style="text-align:right" , 104 , 172.939604(5) , 8.24(8) h , β⁻ , ¹⁷³Yb , (1/2+) , , , - , style="text-indent:1em" , ^173mTm , colspan="3" style="text-indent:2em" , 317.73(20) keV , 10(3) μs , , , (7/2−) , , , - , ¹⁷⁴Tm , style="text-align:right" , 69 , style="text-align:right" , 105 , 173.94217(5) , 5.4(1) min , β⁻ , ¹⁷⁴Yb , (4)− , , , - , ¹⁷⁵Tm , style="text-align:right" , 69 , style="text-align:right" , 106 , 174.94384(5) , 15.2(5) min , β⁻ , ¹⁷⁵Yb , (1/2+) , , , - , ¹⁷⁶Tm , style="text-align:right" , 69 , style="text-align:right" , 107 , 175.94699(11) , 1.85(3) min , β⁻ , ¹⁷⁶Yb , (4+) , , , - , ¹⁷⁷Tm , style="text-align:right" , 69 , style="text-align:right" , 108 , 176.94904(32)# , 90(6) s , β⁻ , ¹⁷⁷Yb , (7/2−) , , , - , ¹⁷⁸Tm , style="text-align:right" , 69 , style="text-align:right" , 109 , 177.95264(43)# , 30# s , β⁻ , ¹⁷⁸Yb , , , , - , ¹⁷⁹Tm , style="text-align:right" , 69 , style="text-align:right" , 110 , 178.95534(54)# , 20# s , β⁻ , ¹⁷⁹Yb , 1/2+# , ,

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 Thulium

Thulium Thulium is a chemical element with the symbol Tm and atomic number 69. It is the thirteenth and third-last element in the lanthanide series. Like the other lanthanides, the most common oxidation state is +3, seen in its oxide, halides and other c ...