Naturally occurring

ruthenium Ruthenium is a chemical element with the symbol Ru and atomic number 44. It is a rare transition metal belonging to the platinum group of the periodic table. Like the other metals of the platinum group, ruthenium is inert to most other chemical ...

(₄₄Ru) is composed of seven 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 ...

s. Additionally, 27 radioactive isotopes have been discovered. Of these

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, the most stable are ¹⁰⁶Ru, 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 373.59 days; ¹⁰³Ru, with a half-life of 39.26 days and ⁹⁷Ru, with a half-life of 2.9 days. Twenty-four other radioisotopes have been characterized with

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 ...

s ranging from 86.95 u (⁸⁷Ru) to 119.95 u (¹²⁰Ru). Most of these have half-lives that are less than five minutes, except ⁹⁴Ru (half-life: 51.8 minutes), ⁹⁵Ru (half-life: 1.643 hours), and ¹⁰⁵Ru (half-life: 4.44 hours). The primary decay mode before the most abundant isotope, ¹⁰²Ru, 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 product before ¹⁰²Ru is

technetium Technetium is a chemical element with the symbol Tc and atomic number 43. It is the lightest element whose isotopes are all radioactive. All available technetium is produced as a synthetic element. Naturally occurring technetium is a spontaneous ...

and the primary product after is

rhodium Rhodium is a chemical element with the symbol Rh and atomic number 45. It is a very rare, silvery-white, hard, corrosion-resistant transition metal. It is a noble metal and a member of the platinum group. It has only one naturally occurring i ...

. Because of the very high volatility of ruthenium tetroxide () ruthenium radioactive isotopes with their relative short half-life are considered as the second most hazardous gaseous isotopes after

iodine-131 Iodine-131 (131I, I-131) is an important radioisotope of iodine discovered by Glenn Seaborg and John Livingood in 1938 at the University of California, Berkeley. It has a radioactive decay half-life of about eight days. It is associated with nu ...

in case of release by a nuclear accident.Ronneau, C., Cara, J., & Rimski-Korsakov, A. (1995)
Oxidation-enhanced emission of ruthenium from nuclear fuel
Journal of Environmental Radioactivity, 26(1), 63-70.Backman, U., Lipponen, M., Auvinen, A., Jokiniemi, J., & Zilliacus, R. (2004)
Ruthenium behaviour in severe nuclear accident conditions
Final report (No. NKS–100). Nordisk Kernesikkerhedsforskning.Beuzet, E., Lamy, J. S., Perron, H., Simoni, E., & Ducros, G. (2012)
Ruthenium release modelling in air and steam atmospheres under severe accident conditions using the MAAP4 code
Nuclear Engineering and Design, 246, 157-162. The two most important isotopes of ruthenium in case of nuclear accident are these with the longest half-life: ¹⁰³Ru (≥ 1 month) and ¹⁰⁶Ru (≥ 1 year).

List of isotopes

, - , ⁸⁷Ru , style="text-align:right" , 44 , style="text-align:right" , 43 , 86.94918(64)# , 50# ms 1.5 µs, β⁺ , ⁸⁷Tc , 1/2−# , , , - , ⁸⁸Ru , style="text-align:right" , 44 , style="text-align:right" , 44 , 87.94026(43)# , 1.3(3) s .2(+3−2) s, β⁺ , ⁸⁸Tc , 0+ , , , - , ⁸⁹Ru , style="text-align:right" , 44 , style="text-align:right" , 45 , 88.93611(54)# , 1.38(11) s , β⁺ , ⁸⁹Tc , (7/2)(+#) , , , - , ⁹⁰Ru , style="text-align:right" , 44 , style="text-align:right" , 46 , 89.92989(32)# , 11.7(9) s , β⁺ , ⁹⁰Tc , 0+ , , , - , ⁹¹Ru , style="text-align:right" , 44 , style="text-align:right" , 47 , 90.92629(63)# , 7.9(4) s , β⁺ , ⁹¹Tc , (9/2+) , , , - , rowspan=3 style="text-indent:1em" , ^91mRu , rowspan=3 colspan="3" style="text-indent:2em" , 80(300)# keV , rowspan=3, 7.6(8) s , β⁺ (>99.9%) , ⁹¹Tc , rowspan=3, (1/2−) , rowspan=3, , rowspan=3, , - , IT (<.1%) , ⁹¹Ru , - , β⁺, p (<.1%) , ⁹⁰Mo , - , ⁹²Ru , style="text-align:right" , 44 , style="text-align:right" , 48 , 91.92012(32)# , 3.65(5) min , β⁺ , ⁹²Tc , 0+ , , , - , ⁹³Ru , style="text-align:right" , 44 , style="text-align:right" , 49 , 92.91705(9) , 59.7(6) s , β⁺ , ⁹³Tc , (9/2)+ , , , - , rowspan=3 style="text-indent:1em" , ^93m1Ru , rowspan=3 colspan="3" style="text-indent:2em" , 734.40(10) keV , rowspan=3, 10.8(3) s , β⁺ (78%) , ⁹³Tc , rowspan=3, (1/2)− , rowspan=3, , rowspan=3, , - , IT (22%) , ⁹³Ru , - , β⁺, p (.027%) , ⁹²Mo , - , style="text-indent:1em" , ^93m2Ru , colspan="3" style="text-indent:2em" , 2082.6(9) keV , 2.20(17) µs , , , (21/2)+ , , , - , ⁹⁴Ru , style="text-align:right" , 44 , style="text-align:right" , 50 , 93.911360(14) , 51.8(6) min , β⁺ , ⁹⁴Tc , 0+ , , , - , style="text-indent:1em" , ^94mRu , colspan="3" style="text-indent:2em" , 2644.55(25) keV , 71(4) µs , , , (8+) , , , - , ⁹⁵Ru , style="text-align:right" , 44 , style="text-align:right" , 51 , 94.910413(13) , 1.643(14) h , β⁺ , ⁹⁵Tc , 5/2+ , , , - , ⁹⁶Ru , style="text-align:right" , 44 , style="text-align:right" , 52 , 95.907598(8) , 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 β⁺β⁺ decay to ⁹⁶Mo with a half-life over 6.7×10¹⁶ years , 0+ , 0.0554(14) , , - , ⁹⁷Ru , style="text-align:right" , 44 , style="text-align:right" , 53 , 96.907555(9) , 2.791(4) d , β⁺ , ^97mTc , 5/2+ , , , - , ⁹⁸Ru , style="text-align:right" , 44 , style="text-align:right" , 54 , 97.905287(7) , colspan=3 align=center, StableTheoretically capable of spontaneous fission , 0+ , 0.0187(3) , , - , ⁹⁹Ru , style="text-align:right" , 44 , style="text-align:right" , 55 , 98.9059393(22) , colspan=3 align=center, Stable , 5/2+ , 0.1276(14) , , - , ¹⁰⁰Ru , style="text-align:right" , 44 , style="text-align:right" , 56 , 99.9042195(22) , colspan=3 align=center, Stable , 0+ , 0.1260(7) , , - , ¹⁰¹Ru Fission product , style="text-align:right" , 44 , style="text-align:right" , 57 , 100.9055821(22) , colspan=3 align=center, Stable , 5/2+ , 0.1706(2) , , - , style="text-indent:1em" , ^101mRu , colspan="3" style="text-indent:2em" , 527.56(10) keV , 17.5(4) µs , , , 11/2− , , , - , ¹⁰²Ru , style="text-align:right" , 44 , style="text-align:right" , 58 , 101.9043493(22) , colspan=3 align=center, Stable , 0+ , 0.3155(14) , , - , ¹⁰³Ru , style="text-align:right" , 44 , style="text-align:right" , 59 , 102.9063238(22) , 39.26(2) d , β⁻ , ¹⁰³Rh , 3/2+ , , , - , style="text-indent:1em" , ^103mRu , colspan="3" style="text-indent:2em" , 238.2(7) keV , 1.69(7) ms , IT , ¹⁰³Ru , 11/2− , , , - , ¹⁰⁴Ru , style="text-align:right" , 44 , style="text-align:right" , 60 , 103.905433(3) , colspan=3 align=center, Observationally StableBelieved to undergo β⁻β⁻ decay to ¹⁰⁴Pd , 0+ , 0.1862(27) , , - , ¹⁰⁵Ru , style="text-align:right" , 44 , style="text-align:right" , 61 , 104.907753(3) , 4.44(2) h , β⁻ , ¹⁰⁵Rh , 3/2+ , , , - , ¹⁰⁶Ru , style="text-align:right" , 44 , style="text-align:right" , 62 , 105.907329(8) , 373.59(15) d , β⁻ , ¹⁰⁶Rh , 0+ , , , - , ¹⁰⁷Ru , style="text-align:right" , 44 , style="text-align:right" , 63 , 106.90991(13) , 3.75(5) min , β⁻ , ¹⁰⁷Rh , (5/2)+ , , , - , ¹⁰⁸Ru , style="text-align:right" , 44 , style="text-align:right" , 64 , 107.91017(12) , 4.55(5) min , β⁻ , ¹⁰⁸Rh , 0+ , , , - , ¹⁰⁹Ru , style="text-align:right" , 44 , style="text-align:right" , 65 , 108.91320(7) , 34.5(10) s , β⁻ , ¹⁰⁹Rh , (5/2+)# , , , - , ¹¹⁰Ru , style="text-align:right" , 44 , style="text-align:right" , 66 , 109.91414(6) , 11.6(6) s , β⁻ , ¹¹⁰Rh , 0+ , , , - , ¹¹¹Ru , style="text-align:right" , 44 , style="text-align:right" , 67 , 110.91770(8) , 2.12(7) s , β⁻ , ¹¹¹Rh , (5/2+) , , , - , ¹¹²Ru , style="text-align:right" , 44 , style="text-align:right" , 68 , 111.91897(8) , 1.75(7) s , β⁻ , ¹¹²Rh , 0+ , , , - , ¹¹³Ru , style="text-align:right" , 44 , style="text-align:right" , 69 , 112.92249(8) , 0.80(5) s , β⁻ , ¹¹³Rh , (5/2+) , , , - , style="text-indent:1em" , ^113mRu , colspan="3" style="text-indent:2em" , 130(18) keV , 510(30) ms , , , (11/2−) , , , - , rowspan=2, ¹¹⁴Ru , rowspan=2 style="text-align:right" , 44 , rowspan=2 style="text-align:right" , 70 , rowspan=2, 113.92428(25)# , rowspan=2, 0.53(6) s , β⁻ (>99.9%) , ¹¹⁴Rh , rowspan=2, 0+ , rowspan=2, , rowspan=2, , - , β⁻, n (<.1%) , ¹¹³Rh , - , rowspan=2, ¹¹⁵Ru , rowspan=2 style="text-align:right" , 44 , rowspan=2 style="text-align:right" , 71 , rowspan=2, 114.92869(14) , rowspan=2, 740(80) ms , β⁻ (>99.9%) , ¹¹⁵Rh , rowspan=2, , rowspan=2, , rowspan=2, , - , β⁻, n (<.1%) , ¹¹⁴Rh , - , ¹¹⁶Ru , style="text-align:right" , 44 , style="text-align:right" , 72 , 115.93081(75)# , 400# ms 300 ns, β⁻ , ¹¹⁶Rh , 0+ , , , - , ¹¹⁷Ru , style="text-align:right" , 44 , style="text-align:right" , 73 , 116.93558(75)# , 300# ms 300 ns, β⁻ , ¹¹⁷Rh , , , , - , ¹¹⁸Ru , style="text-align:right" , 44 , style="text-align:right" , 74 , 117.93782(86)# , 200# ms 300 ns, β⁻ , ¹¹⁸Rh , 0+ , , , - , ¹¹⁹Ru , style="text-align:right" , 44 , style="text-align:right" , 75 , 118.94284(75)# , 170# ms 300 ns, , , , , , - , ¹²⁰Ru , style="text-align:right" , 44 , style="text-align:right" , 76 , 119.94531(86)# , 80# ms 300 ns, , , 0+ , , * Geologically exceptional samples are known in which the isotopic composition lies outside the reported range. The uncertainty in the

atomic mass The atomic mass (''m''a or ''m'') is the mass of an atom. Although the SI unit of mass is the kilogram (symbol: kg), atomic mass is often expressed in the non-SI unit dalton (symbol: Da) – equivalently, unified atomic mass unit (u). 1&nb ...

may exceed the stated value for such specimens. * In September 2017 an estimated amount of 100 to 300 TBq (0.3 to 1 g) of ¹⁰⁶Ru was released in Russia, probably in the Ural region. It was, after ruling out release from a reentering satellite, concluded that the source is to be found either in nuclear fuel cycle facilities or radioactive source production. In France levels up to 0.036mBq/m³ of air were measured. It is estimated that over distances of the order of a few tens of kilometres around the location of the release levels may exceed the limits for non-dairy foodstuffs.
Detection of ruthenium 106 in France and in Europe, IRSN France (9 Nov 2017)

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 Isotopes of ruthenium, Ruthenium

Ruthenium Ruthenium is a chemical element with the symbol Ru and atomic number 44. It is a rare transition metal belonging to the platinum group of the periodic table. Like the other metals of the platinum group, ruthenium is inert to most other chemical ...