Isotopes of strontium

The alkaline earth metal strontium (₃₈Sr) has four stable, naturally occurring isotopes: ⁸⁴Sr (0.56%), ⁸⁶Sr (9.86%), ⁸⁷Sr (7.0%) and ⁸⁸Sr (82.58%), giving it a standard atomic weight of 87.62.

Only ⁸⁷Sr is radiogenic; it is produced by decay from the radioactive alkali metal ⁸⁷Rb, which has a half-life of 4.97 × 10¹⁰ years (i.e. more than three times longer than the current age of the universe). Thus, there are two sources of ⁸⁷Sr in any material: primordial, formed during nucleosynthesis along with ⁸⁴Sr, ⁸⁶Sr and ⁸⁸Sr; and that formed by radioactive decay of ⁸⁷Rb. The ratio ⁸⁷Sr/⁸⁶Sr is the parameter typically reported in geologic investigations; ratios in minerals and rocks have values ranging from about 0.7 to greater than 4.0 (see rubidium–strontium dating). Because strontium has an electron configuration similar to that of calcium, it readily substitutes for calcium in minerals.

In addition to the four stable isotopes, thirty-two unstable isotopes of strontium are known to exist, ranging from ⁷³Sr to ¹⁰⁸Sr. Radioactive isotopes of strontium primarily decay into the neighbouring elements yttrium (⁸⁹Sr and heavier isotopes, via beta minus decay) and rubidium (⁸⁵Sr, ⁸³Sr and lighter isotopes, via positron emission or electron capture). The longest-lived of these isotopes, are ⁹⁰Sr with a half-life of 28.91 years, ⁸⁵Sr at 64.846 days, ⁸⁹Sr at 50.56 days, and ⁸²Sr at 25.35 days. All other strontium isotopes have half-lives shorter than 10 hours, most under 10 minutes.

Strontium-89 is an artificial radioisotope used in treatment of bone cancer; this application utilizes its chemical similarity to calcium, which allows it to substitute calcium in bone structures. In circumstances where cancer patients have widespread and painful bony metastases, the administration of ⁸⁹Sr results in the delivery of beta particles directly to the cancerous portions of the bone, where calcium turnover is greatest.

Strontium-90 is a by-product of nuclear fission, present in nuclear fallout. The 1986 Chernobyl nuclear accident contaminated a vast area with ⁹⁰Sr. It causes health problems, as it substitutes for calcium in bone, giving it a long lifetime in the body. Because it is a long-lived high-energy beta emitter, it is used in SNAP (Systems for Nuclear Auxiliary Power) devices. These devices hold promise for use in spacecraft, remote weather stations, navigational buoys, etc., where a lightweight, long-lived, nuclear-electric power source is required.

In 2020, researchers have found that mirror nuclides ⁷³Sr and ⁷³Br were found to not behave identically to each other as expected.

List of isotopes

|-id=Strontium-73 | rowspan=2|⁷³Sr | rowspan=2 style="text-align:right" |38 | rowspan=2 style="text-align:right" | 35 | rowspan=2|72.96570(43)# | rowspan=2|25.3(14)&nbsp;ms | β⁺, p (63%) | ⁷²Kr | rowspan=2|(5/2−) | rowspan=2| | rowspan=2| |- | β⁺ (37%) | ⁷³Rb |-id=Strontium-74 | ⁷⁴Sr | style="text-align:right" | 38 | style="text-align:right" | 36 | 73.95617(11)# | 27.6(26)&nbsp;ms | β⁺ | ⁷⁴Rb | 0+ | | |-id=Strontium-75 | rowspan=2|⁷⁵Sr | rowspan=2 style="text-align:right" | 38 | rowspan=2 style="text-align:right" | 37 | rowspan=2|74.94995(24) | rowspan=2|85.2(23)&nbsp;ms | β⁺ (94.8%) | ⁷⁵Rb | rowspan=2|(3/2−) | rowspan=2| | rowspan=2| |- | β⁺, p (5.2%) | ⁷⁴Kr |-id=Strontium-76 | rowspan=2|⁷⁶Sr | rowspan=2 style="text-align:right" | 38 | rowspan=2 style="text-align:right" | 38 | rowspan=2|75.941763(37) | rowspan=2|7.89(7)&nbsp;s | β⁺ | ⁷⁶Rb | rowspan=2|0+ | rowspan=2| | rowspan=2| |- | β⁺, p (0.0034%) | ⁷⁵Kr |-id=Strontium-77 | rowspan=2|⁷⁷Sr | rowspan=2 style="text-align:right" | 38 | rowspan=2 style="text-align:right" | 39 | rowspan=2|76.9379455(85) | rowspan=2|9.0(2)&nbsp;s | β⁺ (99.92%) | ⁷⁷Rb | rowspan=2|5/2+ | rowspan=2| | rowspan=2| |- | β⁺, p (0.08%) | ⁷⁶Kr |-id=Strontium-78 | ⁷⁸Sr | style="text-align:right" | 38 | style="text-align:right" | 40 | 77.9321800(80) | 156.1(27)&nbsp;s | β⁺ | ⁷⁸Rb | 0+ | | |-id=Strontium-79 | ⁷⁹Sr | style="text-align:right" | 38 | style="text-align:right" | 41 | 78.9297047(80) | 2.25(10)&nbsp;min | β⁺ | ⁷⁹Rb | 3/2− | | |-id=Strontium-80 | ⁸⁰Sr | style="text-align:right" | 38 | style="text-align:right" | 42 | 79.9245175(37) | 106.3(15)&nbsp;min | β⁺ | ⁸⁰Rb | 0+ | | |-id=Strontium-81 | ⁸¹Sr | style="text-align:right" | 38 | style="text-align:right" | 43 | 80.9232114(34) | 22.3(4)&nbsp;min | β⁺ | ⁸¹Rb | 1/2− | | |-id=Strontium-81m1 | style="text-indent:1em" | ^81m1Sr | colspan="3" style="text-indent:2em" | 79.23(4)&nbsp;keV | 390(50)&nbsp;ns | IT | ⁸¹Sr | (5/2)− | | |-id=Strontium-81m2 | style="text-indent:1em" | ^81m2Sr | colspan="3" style="text-indent:2em" | 89.05(7)&nbsp;keV | 6.4(5)&nbsp;μs | | | (7/2+) | | |-id=Strontium-82 | ⁸²Sr | style="text-align:right" | 38 | style="text-align:right" | 44 | 81.9183998(64) | 25.35(3)&nbsp;d | EC | ⁸²Rb | 0+ | | |-id=Strontium-83 | ⁸³Sr | style="text-align:right" | 38 | style="text-align:right" | 45 | 82.9175544(73) | 32.41(3)&nbsp;h | β⁺ | ⁸³Rb | 7/2+ | | |-id=Strontium-83m | style="text-indent:1em" | ^83mSr | colspan="3" style="text-indent:2em" | 259.15(9)&nbsp;keV | 4.95(12)&nbsp;s | IT | ⁸³Sr | 1/2− | | |-id=Strontium-84 | ⁸⁴Sr | style="text-align:right" | 38 | style="text-align:right" | 46 | 83.9134191(13) | colspan=3 align=center|Observationally Stable | 0+ | 0.0056(2) | |-id=Strontium-85 | ⁸⁵Sr | style="text-align:right" | 38 | style="text-align:right" | 47 | 84.9129320(30) | 64.846(6)&nbsp;d | EC | ⁸⁵Rb | 9/2+ | | |-id=Strontium-85m | rowspan=2 style="text-indent:1em" | ^85mSr | rowspan=2 colspan="3" style="text-indent:2em" | 238.79(5)&nbsp;keV | rowspan=2|67.63(4)&nbsp;min | IT (86.6%) | ⁸⁵Sr | rowspan=2|1/2− | rowspan=2| | rowspan=2| |- | β⁺ (13.4%) | ⁸⁵Rb |-id=Strontium-86 | ⁸⁶Sr | style="text-align:right" | 38 | style="text-align:right" | 48 | 85.9092607247(56) | colspan=3 align=center|Stable | 0+ | 0.0986(20) | |-id=Strontium-86m | style="text-indent:1em" | ^86mSr | colspan="3" style="text-indent:2em" | 2956.09(12)&nbsp;keV | 455(7)&nbsp;ns | IT | ⁸⁶Sr | 8+ | | |-id=Strontium-87 | ⁸⁷Sr | style="text-align:right" | 38 | style="text-align:right" | 49 | 86.9088774945(55) | colspan=3 align=center|Stable | 9/2+ | 0.0700(20) | |-id=Strontium-87m | rowspan=2 style="text-indent:1em" | ^87mSr | rowspan=2 colspan="3" style="text-indent:2em" | 388.5287(23)&nbsp;keV | rowspan=2|2.805(9)&nbsp;h | IT (99.70%) | ⁸⁷Sr | rowspan=2|1/2− | rowspan=2| | rowspan=2| |- | EC (0.30%) | ⁸⁷Rb |-id=Strontium-88 | ⁸⁸Sr | style="text-align:right" | 38 | style="text-align:right" | 50 | 87.905612253(6) | colspan=3 align=center|Stable | 0+ | 0.8258(35) | |- | ⁸⁹Sr | style="text-align:right" | 38 | style="text-align:right" | 51 | 88.907450808(98) | 50.563(25)&nbsp;d | β^− | ⁸⁹Y | 5/2+ | | |- | ⁹⁰Sr | style="text-align:right" | 38 | style="text-align:right" | 52 | 89.9077279(16) | 28.91(3)&nbsp;y | β^− | ⁹⁰Y | 0+ | | |-id=Strontium-91 | ⁹¹Sr | style="text-align:right" | 38 | style="text-align:right" | 53 | 90.9101959(59) | 9.65(6)&nbsp;h | β^− | ⁹¹Y | 5/2+ | | |-id=Strontium-92 | ⁹²Sr | style="text-align:right" | 38 | style="text-align:right" | 54 | 91.9110382(37) | 2.611(17)&nbsp;h | β^− | ⁹²Y | 0+ | | |-id=Strontium-93 | ⁹³Sr | style="text-align:right" | 38 | style="text-align:right" | 55 | 92.9140243(81) | 7.43(3)&nbsp;min | β^− | ⁹³Y | 5/2+ | | |-id=Strontium-94 | ⁹⁴Sr | style="text-align:right" | 38 | style="text-align:right" | 56 | 93.9153556(18) | 75.3(2)&nbsp;s | β^− | ⁹⁴Y | 0+ | | |-id=Strontium-95 | ⁹⁵Sr | style="text-align:right" | 38 | style="text-align:right" | 57 | 94.9193583(62) | 23.90(14)&nbsp;s | β^− | ⁹⁵Y | 1/2+ | | |-id=Strontium-96 | ⁹⁶Sr | style="text-align:right" | 38 | style="text-align:right" | 58 | 95.9217190(91) | 1.059(8)&nbsp;s | β^− | ⁹⁶Y | 0+ | | |-id=Strontium-97 | rowspan=2|⁹⁷Sr | rowspan=2 style="text-align:right" | 38 | rowspan=2 style="text-align:right" | 59 | rowspan=2|96.9263756(36) | rowspan=2|432(4)&nbsp;ms | β^− (99.98%) | ⁹⁷Y | rowspan=2|1/2+ | rowspan=2| | rowspan=2| |- | β^−, n (0.02%) | ⁹⁶Y |-id=Strontium-97m1 | style="text-indent:1em" | ^97m1Sr | colspan="3" style="text-indent:2em" | 308.13(11)&nbsp;keV | 175.2(21)&nbsp;ns | IT | ⁹⁷Sr | 7/2+ | | |-id=Strontium-97m2 | style="text-indent:1em" | ^97m2Sr | colspan="3" style="text-indent:2em" | 830.83(23)&nbsp;keV | 513(5)&nbsp;ns | IT | ⁹⁷Sr | (9/2+) | | |-id=Strontium-98 | rowspan=2|⁹⁸Sr | rowspan=2 style="text-align:right" | 38 | rowspan=2 style="text-align:right" | 60 | rowspan=2|97.9286926(35) | rowspan=2|653(2)&nbsp;ms | β^− (99.77%) | ⁹⁸Y | rowspan=2|0+ | rowspan=2| | rowspan=2| |- | β^−, n (0.23%) | ⁹⁷Y |-id=Strontium-99 | rowspan=2|⁹⁹Sr | rowspan=2 style="text-align:right" | 38 | rowspan=2 style="text-align:right" | 61 | rowspan=2|98.9328836(51) | rowspan=2|269.2(10)&nbsp;ms | β^− (99.90%) | ⁹⁹Y | rowspan=2|3/2+ | rowspan=2| | rowspan=2| |- | β^−, n (0.100%) | ⁹⁸Y |-id=Strontium-100 | rowspan=2|¹⁰⁰Sr | rowspan=2 style="text-align:right" | 38 | rowspan=2 style="text-align:right" | 62 | rowspan=2|99.9357833(74) | rowspan=2|202.1(17)&nbsp;ms | β^− (98.89%) | ¹⁰⁰Y | rowspan=2|0+ | rowspan=2| | rowspan=2| |- | β^−, n (1.11%) | ⁹⁹Y |-id=Strontium-100m | style="text-indent:1em" | ^100mSr | colspan="3" style="text-indent:2em" | 1618.72(20)&nbsp;keV | 122(9)&nbsp;ns | IT | ¹⁰⁰Sr | (4−) | | |-id=Strontium-101 | rowspan=2|¹⁰¹Sr | rowspan=2 style="text-align:right" | 38 | rowspan=2 style="text-align:right" | 63 | rowspan=2|100.9406063(91) | rowspan=2|113.7(17)&nbsp;ms | β^− (97.25%) | ¹⁰¹Y | rowspan=2|(5/2−) | rowspan=2| | rowspan=2| |- | β^−, n (2.75%) | ¹⁰⁰Y |-id=Strontium-102 | rowspan=2|¹⁰²Sr | rowspan=2 style="text-align:right" | 38 | rowspan=2 style="text-align:right" | 64 | rowspan=2|101.944005(72) | rowspan=2|69(6)&nbsp;ms | β^− (94.5%) | ¹⁰²Y | rowspan=2|0+ | rowspan=2| | rowspan=2| |- | β^−, n (5.5%) | ¹⁰¹Y |-id=Strontium-103 | ¹⁰³Sr | style="text-align:right" | 38 | style="text-align:right" | 65 | 102.94924(22)# | 53(10)&nbsp;ms | β^− | ¹⁰³Y | 5/2+# | | |-id=Strontium-104 | ¹⁰⁴Sr | style="text-align:right" | 38 | style="text-align:right" | 66 | 103.95302(32)# | 50.6(42)&nbsp;ms | β^− | ¹⁰⁴Y | 0+ | | |-id=Strontium-105 | ¹⁰⁵Sr | style="text-align:right" | 38 | style="text-align:right" | 67 | 104.95900(54)# | 39(5)&nbsp;ms | β^− | ¹⁰⁵Y | 5/2+# | | |-id=Strontium-106 | ¹⁰⁶Sr | style="text-align:right" | 38 | style="text-align:right" | 68 | 105.96318(64)# | 21(8)&nbsp;ms | β^− | ¹⁰⁶Y | 0+ | | |-id=Strontium-107 | ¹⁰⁷Sr | style="text-align:right" | 38 | style="text-align:right" | 69 | 106.96967(75)# | 25#&nbsp;ms<br />[>400&nbsp;ns] | | | 1/2+# | | |-id=Strontium-108 | ¹⁰⁸Sr | style="text-align:right" | 38 | style="text-align:right" | 70 | | | | | | |

See also

Daughter products other than strontium

• Isotopes of yttrium
• Isotopes of rubidium
• Isotopes of krypton

References