Selenium Selenium is a chemical element; it has symbol (chemistry), symbol Se and atomic number 34. It has various physical appearances, including a brick-red powder, a vitreous black solid, and a grey metallic-looking form. It seldom occurs in this elem ...

has six natural

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 that occur in significant quantities, along with the trace isotope ⁷⁹Se, which occurs in minute quantities in

uranium Uranium is a chemical element; it has chemical symbol, symbol U and atomic number 92. It is a silvery-grey metal in the actinide series of the periodic table. A uranium atom has 92 protons and 92 electrons, of which 6 are valence electrons. Ura ...

ores. Five of these isotopes are

stable A stable is a building in which working animals are kept, especially horses or oxen. The building is usually divided into stalls, and may include storage for equipment and feed. Styles There are many different types of stables in use tod ...

: ⁷⁴Se, ⁷⁶Se, ⁷⁷Se, ⁷⁸Se, and ⁸⁰Se. The last three also occur as

fission products Nuclear fission products are the atomic fragments left after a large atomic nucleus undergoes nuclear fission. Typically, a large nucleus like that of uranium fissions by splitting into two smaller nuclei, along with a few neutrons, the releas ...

, along with ⁷⁹Se, which has 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 327,000 years,The half-life of ⁷⁹Se
and ⁸²Se, which has a very long half-life (~10²⁰ years, decaying via

double beta decay In nuclear physics, double beta decay is a type of radioactive decay in which two neutrons are simultaneously transformed into two protons, or vice versa, inside an atomic nucleus. As in single beta decay, this process allows the atom to move cl ...

to ⁸²Kr) and for practical purposes can be considered to be stable. There are 23 other unstable isotopes that have been characterized, the longest-lived being ⁷⁹Se with a half-life 327,000 years, ⁷⁵Se with a half-life of 120 days, and ⁷²Se with a half-life of 8.40 days. Of the other isotopes, ⁷³Se has the longest half-life, 7.15 hours; most others have half-lives not exceeding 38 seconds.

List of isotopes

, -id=Selenium-63 , rowspan=3, ⁶³Se , rowspan=3 style="text-align:right" , 34 , rowspan=3 style="text-align:right" , 29 , rowspan=3, 62.98191(54)# , rowspan=3, 13.2(39) ms , β⁺, p (89%) , ⁶²Ge , rowspan=3, 3/2−# , rowspan=3, , rowspan=3, , - , β⁺ (11%) , ⁶³As , - , 2p? (<0.5%) , ⁶¹Ge , -id=Selenium-64 , rowspan=2, ⁶⁴Se , rowspan=2 style="text-align:right" , 34 , rowspan=2 style="text-align:right" , 30 , rowspan=2, 63.97117(54)# , rowspan=2, 22.6(2) ms , β⁺? , ⁶⁴As , rowspan=2, 0+ , rowspan=2, , rowspan=2, , - , β⁺, p? , ⁶³Ge , -id=Selenium-65 , rowspan=2, ⁶⁵Se , rowspan=2 style="text-align:right" , 34 , rowspan=2 style="text-align:right" , 31 , rowspan=2, 64.96455(32)# , rowspan=2, 34.2(7) ms , β⁺, p (87%) , ⁶⁴Ge , rowspan=2, 3/2−# , rowspan=2, , rowspan=2, , - , β⁺ (13%) , ⁶⁵As , -id=Selenium-66 , rowspan=2, ⁶⁶Se , rowspan=2 style="text-align:right" , 34 , rowspan=2 style="text-align:right" , 32 , rowspan=2, 65.95528(22)# , rowspan=2, 54(4) ms , β⁺ , ⁶⁶As , rowspan=2, 0+ , rowspan=2, , rowspan=2, , - , β⁺, p? , ⁶⁵Ge , -id=Selenium-67 , rowspan=2, ⁶⁷Se , rowspan=2 style="text-align:right" , 34 , rowspan=2 style="text-align:right" , 33 , rowspan=2, 66.949994(72) , rowspan=2, 133(4) ms , β⁺ (99.5%) , ⁶⁷As , rowspan=2, 5/2−# , rowspan=2, , rowspan=2, , - , β⁺, p (0.5%) , ⁶⁶Ge , -id=Selenium-68 , ⁶⁸Se , style="text-align:right" , 34 , style="text-align:right" , 34 , 67.94182524(53) , 35.5(7) s , β⁺ , ⁶⁸As , 0+ , , , -id=Selenium-69 , rowspan=2, ⁶⁹Se , rowspan=2 style="text-align:right" , 34 , rowspan=2 style="text-align:right" , 35 , rowspan=2, 68.9394148(16) , rowspan=2, 27.4(2) s , β⁺ (99.95%) , ⁶⁹As , rowspan=2, 1/2− , rowspan=2, , rowspan=2, , - , β⁺, p (.052%) , ⁶⁸Ge , -id=Selenium-69m1 , style="text-indent:1em" , ^69m1Se , colspan="3" style="text-indent:2em" , 38.85(22) keV , 2.0(2) μs , IT , ⁶⁹Se , 5/2− , , , -id=Selenium-69m2 , style="text-indent:1em" , ^69m2Se , colspan="3" style="text-indent:2em" , 574.0(4) keV , 955(16) ns , IT , ⁶⁹Se , 9/2+ , , , -id=Selenium-70 , ⁷⁰Se , style="text-align:right" , 34 , style="text-align:right" , 36 , 69.9335155(17) , 41.1(3) min , β⁺ , ⁷⁰As , 0+ , , , -id=Selenium-71 , ⁷¹Se , style="text-align:right" , 34 , style="text-align:right" , 37 , 70.9322094(30) , 4.74(5) min , β⁺ , ⁷¹As , (5/2−) , , , -id=Selenium-71m1 , style="text-indent:1em" , ^71m1Se , colspan="3" style="text-indent:2em" , 48.79(5) keV , 5.6(7) μs , IT , ⁷¹Se , (1/2−) , , , -id=Selenium-71m2 , style="text-indent:1em" , ^71m2Se , colspan="3" style="text-indent:2em" , 260.48(10) keV , 19.0(5) μs , IT , ⁷¹Se , (9/2+) , , , -id=Selenium-72 , ⁷²Se , style="text-align:right" , 34 , style="text-align:right" , 38 , 71.9271405(21) , 8.40(8) d , EC , ⁷²As , 0+ , , , -id=Selenium-73 , ⁷³Se , style="text-align:right" , 34 , style="text-align:right" , 39 , 72.9267549(80) , 7.15(9) h , β⁺ , ⁷³As , 9/2+ , , , -id=Selenium-73m , rowspan=2 style="text-indent:1em" , ^73mSe , rowspan=2 colspan="3" style="text-indent:2em" , 25.71(4) keV , rowspan=2, 39.8(17) min , IT (72.6%) , ⁷³Se , rowspan=2, 3/2− , rowspan=2, , rowspan=2, , - , β⁺ (27.4%) , ⁷³As , -id=Selenium-74 , ⁷⁴Se , style="text-align:right" , 34 , style="text-align:right" , 40 , 73.922475933(15) , 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 ...

Theoretically capable of β⁺β⁺ decay to ⁷⁴Ge; half-life is above . , 0+ , 0.0086(3) , , -id=Selenium-75 , ⁷⁵Se , style="text-align:right" , 34 , style="text-align:right" , 41 , 74.922522870(78) , 119.78(3) d , EC , ⁷⁵As , 5/2+ , , , -id=Selenium-76 , ⁷⁶Se , style="text-align:right" , 34 , style="text-align:right" , 42 , 75.919213702(17) , colspan=3 align=center, Stable , 0+ , 0.0923(7) , , -id=Selenium-77 , ⁷⁷Se

Fission product Nuclear fission products are the atomic fragments left after a large atomic nucleus undergoes nuclear fission. Typically, a large nucleus like that of uranium fissions by splitting into two smaller nuclei, along with a few neutrons, the releas ...

, style="text-align:right" , 34 , style="text-align:right" , 43 , 76.919914150(67) , colspan=3 align=center, Stable , 1/2− , 0.0760(7) , , -id=Selenium-77m , style="text-indent:1em" , ^77mSe , colspan="3" style="text-indent:2em" , 161.9223(10) keV , 17.36(5) s , IT , ⁷⁷Se , 7/2+ , , , -id=Selenium-78 , ⁷⁸Se , style="text-align:right" , 34 , style="text-align:right" , 44 , 77.91730924(19) , colspan=3 align=center, Stable , 0+ , 0.2369 (22) , , -id=Selenium-79 , ⁷⁹Se

Long-lived fission product Long-lived fission products (LLFPs) are radioactive materials with a long half-life (more than 200,000 years) produced by nuclear fission of uranium and plutonium. Because of their persistent radiotoxicity, it is necessary to isolate them from hum ...

, style="text-align:right" , 34 , style="text-align:right" , 45 , 78.91849925(24) , 3.27(28)×10⁵ y , β⁻ , ⁷⁹Br , 7/2+ , , , -id=Selenium-79m , rowspan=2 style="text-indent:1em" , ^79mSe , rowspan=2 colspan="3" style="text-indent:2em" , 95.77(3) keV , rowspan=2, 3.900(18) min , IT (99.94%) , ⁷⁹Se , rowspan=2, 1/2− , rowspan=2, , rowspan=2, , - , β⁻ (0.056%) , ⁷⁹Br , -id=Selenium-80 , ⁸⁰Se , style="text-align:right" , 34 , style="text-align:right" , 46 , 79.9165218(10) , colspan=3 align=center, Observationally StableTheoretically capable of β⁻β⁻ decay to ⁸⁰Kr , 0+ , 0.4980(36) , , -id=Selenium-81 , ⁸¹Se , style="text-align:right" , 34 , style="text-align:right" , 47 , 80.9179930(10) , 18.45(12) min , β⁻ , ⁸¹Br , 1/2− , , , -id=Selenium-81m , rowspan=2 style="text-indent:1em" , ^81mSe , rowspan=2 colspan="3" style="text-indent:2em" , 103.00(6) keV , rowspan=2, 57.28(2) min , IT (99.95%) , ⁸¹Se , rowspan=2, 7/2+ , rowspan=2, , rowspan=2, , - , β⁻ (0.051%) , ⁸¹Br , -id=Selenium-82 , ⁸²Se Primordial

radionuclide 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 ...

, style="text-align:right" , 34 , style="text-align:right" , 48 , 81.91669953(50) , 8.76(15)×10¹⁹ y , β⁻β⁻ , ⁸²Kr , 0+ , 0.0882(15) , , -id=Selenium-83 , ⁸³Se , style="text-align:right" , 34 , style="text-align:right" , 49 , 82.9191186(33) , 22.25(4) min , β⁻ , ⁸³Br , 9/2+ , , , -id=Selenium-83m , style="text-indent:1em" , ^83mSe , colspan="3" style="text-indent:2em" , 228.92(7) keV , 70.1(4) s , β⁻ , ⁸³Br , 1/2− , , , -id=Selenium-84 , ⁸⁴Se , style="text-align:right" , 34 , style="text-align:right" , 50 , 83.9184668(21) , 3.26(10) min , β⁻ , ⁸⁴Br , 0+ , , , -id=Selenium-85 , ⁸⁵Se , style="text-align:right" , 34 , style="text-align:right" , 51 , 84.9222608(28) , 32.9(3) s , β⁻ , ⁸⁵Br , (5/2)+ , , , -id=Selenium-86 , rowspan=2, ⁸⁶Se , rowspan=2 style="text-align:right" , 34 , rowspan=2 style="text-align:right" , 52 , rowspan=2, 85.9243117(27) , rowspan=2, 14.3(3) s , β⁻ , ⁸⁶Br , rowspan=2, 0+ , rowspan=2, , rowspan=2, , - , β⁻, n? , ⁸⁵Br , -id=Selenium-87 , rowspan=2, ⁸⁷Se , rowspan=2 style="text-align:right" , 34 , rowspan=2 style="text-align:right" , 53 , rowspan=2, 86.9286886(24) , rowspan=2, 5.50(6) s , β⁻ (99.50%) , ⁸⁷Br , rowspan=2, (3/2+) , rowspan=2, , rowspan=2, , - , β⁻, n (0.60%) , ⁸⁶Br , -id=Selenium-88 , rowspan=2, ⁸⁸Se , rowspan=2 style="text-align:right" , 34 , rowspan=2 style="text-align:right" , 54 , rowspan=2, 87.9314175(36) , rowspan=2, 1.53(6) s , β⁻ (99.01%) , ⁸⁸Br , rowspan=2, 0+ , rowspan=2, , rowspan=2, , - , β⁻, n (0.99%) , ⁸⁷Br , -id=Selenium-89 , rowspan=2, ⁸⁹Se , rowspan=2 style="text-align:right" , 34 , rowspan=2 style="text-align:right" , 55 , rowspan=2, 88.9366691(40) , rowspan=2, 430(50) ms , β⁻ (92.2%) , ⁸⁹Br , rowspan=2, 5/2+# , rowspan=2, , rowspan=2, , - , β⁻, n (7.8%) , ⁸⁸Br , -id=Selenium-90 , rowspan=2, ⁹⁰Se , rowspan=2 style="text-align:right" , 34 , rowspan=2 style="text-align:right" , 56 , rowspan=2, 89.94010(35) , rowspan=2, 210(80) ms , β⁻ , ⁹⁰Br , rowspan=2, 0+ , rowspan=2, , rowspan=2, , - , β⁻, n? , ⁸⁹Br , -id=Selenium-91 , rowspan=3, ⁹¹Se , rowspan=3 style="text-align:right" , 34 , rowspan=3 style="text-align:right" , 57 , rowspan=3, 90.94570(47) , rowspan=3, 270(50) ms , β⁻ (79%) , ⁹¹Br , rowspan=3, 1/2+# , rowspan=3, , rowspan=3, , - , β⁻, n (21%) , ⁹⁰Br , - , β⁻, 2n? , ⁸⁹Br , -id=Selenium-92 , rowspan=3, ⁹²Se , rowspan=3 style="text-align:right" , 34 , rowspan=3 style="text-align:right" , 58 , rowspan=3, 91.94984(43)# , rowspan=3, 90# ms 300 ns, β⁻? , ⁹²Br , rowspan=3, 0+ , rowspan=3, , rowspan=3, , - , β⁻, n? , ⁹¹Br , - , β⁻, 2n? , ⁹⁰Br , -id=Selenium-92m , style="text-indent:1em" , ^92mSe , colspan="3" style="text-indent:2em" , 3072(2) keV , 15.7(7) μs , IT , ⁹²Se , (9−) , , , -id=Selenium-93 , rowspan=3, ⁹³Se , rowspan=3 style="text-align:right" , 34 , rowspan=3 style="text-align:right" , 59 , rowspan=3, 92.95614(43)# , rowspan=3, 130# ms 300 ns, β⁻? , ⁹³Br , rowspan=3, 1/2+# , rowspan=3, , rowspan=3, , - , β⁻, n? , ⁹²Br , - , β⁻, 2n? , ⁹¹Br , -id=Selenium-93m , style="text-indent:1em" , ^93mSe , colspan="3" style="text-indent:2em" , 678.2(7) keV , 420(100) ns , IT , ⁹³Se , , , , -id=Selenium-94 , rowspan=3, ⁹⁴Se , rowspan=3 style="text-align:right" , 34 , rowspan=3 style="text-align:right" , 60 , rowspan=3, 93.96049(54)# , rowspan=3, 50# ms 300 ns, β⁻? , ⁹⁴Br , rowspan=3, 0+ , rowspan=3, , rowspan=3, , - , β⁻, n? , ⁹³Br , - , β⁻, 2n? , ⁹²Br , -id=Selenium-94m , style="text-indent:1em" , ^94mSe , colspan="3" style="text-indent:2em" , 2430.0(6) keV , 680(50) ns , IT , ⁹⁴Se , (7−) , , , -id=Selenium-95 , rowspan=3, ⁹⁵Se , rowspan=3 style="text-align:right" , 34 , rowspan=3 style="text-align:right" , 61 , rowspan=3, 94.96730(54)# , rowspan=3, 70# ms 400 ns, β⁻? , ⁹⁵Br , rowspan=3, 3/2+# , rowspan=3, , rowspan=3, , - , β⁻, n? , ⁹⁴Br , - , β⁻, 2n? , ⁹³Br , -id=Selenium-96 , ⁹⁶Se , style="text-align:right" , 34 , style="text-align:right" , 62 , , , , , , , , -id=Selenium-97 , ⁹⁷Se , style="text-align:right" , 34 , style="text-align:right" , 63 , , , , , , ,

Use of radioisotopes

The isotope selenium-75 has

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 ...

uses. For example, it is used in high-dose-rate endorectal

brachytherapy Brachytherapy is a form of radiation therapy where a sealed radiation, radiation source is placed inside or next to the area requiring treatment. The word "brachytherapy" comes from the Ancient Greek, Greek word , meaning "short-distance" or "s ...

, as an alternative to

iridium-192 Iridium-192 (symbol 192Ir) is a radioactive isotope of iridium, with a half-life of 73.827 days. It decays by emitting beta (β) particles and gamma (γ) radiation. About 96% of 192Ir decays occur via emission of β and γ radiation, leading to ...

. In paleobiogeochemistry, the ratio in amount of selenium-82 to selenium-76 (i.e, the value of δ^82/76Se) can be used to track down the

redox Redox ( , , reduction–oxidation or oxidation–reduction) is a type of chemical reaction in which the oxidation states of the reactants change. Oxidation is the loss of electrons or an increase in the oxidation state, while reduction is t ...

conditions on Earth during the

Neoproterozoic era The Neoproterozoic Era is the last of the three geologic eras of the Proterozoic eon, spanning from 1 billion to 538.8 million years ago, and is the last era of the Precambrian "supereon". It is preceded by the Mesoproterozoic era and succeeded b ...

in order to gain a deeper understanding of the rapid oxygenation that trigger the emergence of complex organisms.

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 Selenium

List of isotopes

Use of radioisotopes

See also

References