There are 34 known isotopes of krypton (36Kr) with atomic mass numbers from 67 to 103. Naturally occurring krypton is made of five stable isotopes and one () which is slightly radioactive with an extremely long half-life, plus traces of radioisotopes that are produced by cosmic rays in the atmosphere. Atmospheric krypton today is, however, considerably radioactive due almost entirely to artificial 85Kr.
List of isotopes
|-id=Krypton-67 | rowspan=2|67Kr | rowspan=2 style="text-align:right" | 36 | rowspan=2 style="text-align:right" | 31 | rowspan=2|66.98331(46)# | rowspan=2 style="text-align:center" | 2016 | rowspan=2|7.4(29) ms | β+, p (%?) | 66Se | rowspan=2|3/2-# | rowspan=2| | rowspan=2| |- |2p (37%) |65Se |-id=Krypton-68 | 68Kr | style="text-align:right" | 36 | style="text-align:right" | 32 | 67.97249(54)# | style="text-align:center" | 2016 | 21.6(33) ms | β+, p | 67Se | 0+
|-id=Krypton-69 | rowspan=2|69Kr | rowspan=2 style="text-align:right" | 36 | rowspan=2 style="text-align:right" | 33 | rowspan=2|68.96550(32)# | rowspan=2 style="text-align:center" | 1995 | rowspan=2|27.9(8) ms | β+, p (94%) | 68Se | rowspan=2|(5/2−) | rowspan=2| | rowspan=2| |- | β+ (6%) | 69Br |-id=Krypton-70 | rowspan=2|70Kr | rowspan=2 style="text-align:right" | 36 | rowspan=2 style="text-align:right" | 34 | rowspan=2|69.95588(22)# | rowspan=2 style="text-align:center" | 1995 | rowspan=2|45.00(14) ms | β+ (>98.7%) | 70Br | rowspan=2|0+ | rowspan=2| | rowspan=2| |- | β+, p (<1.3%) | 69Se |-id=Krypton-71 | rowspan=2|71Kr | rowspan=2 style="text-align:right" | 36 | rowspan=2 style="text-align:right" | 35 | rowspan=2|70.95027(14) | rowspan=2 style="text-align:center" | 1981 | rowspan=2|98.8(3) ms | β+ (97.9%) | 71Br | rowspan=2|(5/2)− | rowspan=2| | rowspan=2| |- | β+, p (2.1%) | 70Se |-id=Krypton-72 | 72Kr | style="text-align:right" | 36 | style="text-align:right" | 36 | 71.9420924(86) | style="text-align:center" | 1973 | 17.16(18) s | β+ | 72Br | 0+
|-id=Krypton-73 | rowspan=2|73Kr | rowspan=2 style="text-align:right" | 36 | rowspan=2 style="text-align:right" | 37 | rowspan=2|72.9392892(71) | rowspan=2 style="text-align:center" | 1972 | rowspan=2|27.3(10) s | β+ (99.75%) | 73Br | rowspan=2|(3/2)− | rowspan=2| | rowspan=2| |- | β+, p (0.25%) | 72Se |-id=Krypton-73m | style="text-indent:1em" | 73mKr | colspan="3" style="text-indent:2em" | 433.55(13) keV | style="text-align:center" | 1993 | 107(10) ns | IT | 73Kr | (9/2+)
|-id=Krypton-74 | 74Kr | style="text-align:right" | 36 | style="text-align:right" | 38 | 73.9330840(22) | style="text-align:center" | 1960 | 11.50(11) min | β+ | 74Br | 0+
|-id=Krypton-75 | 75Kr | style="text-align:right" | 36 | style="text-align:right" | 39 | 74.9309457(87) | style="text-align:center" | 1960 | 4.60(7) min | β+ | 75Br | 5/2+
|-id=Krypton-76 | 76Kr | style="text-align:right" | 36 | style="text-align:right" | 40 | 75.9259107(43) | style="text-align:center" | 1954 | 14.8(1) h | β+ | 76Br | 0+
|-id=Krypton-77 | 77Kr | style="text-align:right" | 36 | style="text-align:right" | 41 | 76.9246700(21) | style="text-align:center" | 1948 | 72.6(9) min | β+ | 77Br | 5/2+
|-id=Krypton-77m | style="text-indent:1em" | 77mKr | colspan="3" style="text-indent:2em" | 66.50(5) keV | style="text-align:center" | 1975 | 118(12) ns | IT | 77Kr | 3/2−
|-id=Krypton-78 | 78KrPrimordial radionuclide | style="text-align:right" | 36 | style="text-align:right" | 42 | 77.92036634(33) | style="text-align:center" | 1920 |9.2((stat),(sys)) y |Double EC |78Se | 0+ | 0.00355(3) | |-id=Krypton-79 | 79Kr | style="text-align:right" | 36 | style="text-align:right" | 43 | 78.9200829(37) | style="text-align:center" | 1948 | 35.04(10) h | β+ | 79Br | 1/2−
|-id=Krypton-79m | style="text-indent:1em" | 79mKr | colspan="3" style="text-indent:2em" | 129.77(5) keV | style="text-align:center" | 1969 | 50(3) s | IT | 79Kr | 7/2+
|-id=Krypton-80 | 80Kr | style="text-align:right" | 36 | style="text-align:right" | 44 | 79.91637794(75) | style="text-align:center" | 1920 | colspan=3 align=center|Stable | 0+ | 0.02286(10) | |-id=Krypton-81m | 81KrUsed to date groundwater | style="text-align:right" | 36 | style="text-align:right" | 45 | 80.9165897(12) | style="text-align:center" | 1950 | 2.29(11)×105 y | EC | 81Br | 7/2+
|-id=Krypton-81m | rowspan=2 style="text-indent:1em" | 81mKr | rowspan=2 colspan="3" style="text-indent:2em" | 190.64(4) keV | rowspan=2 style="text-align:center" | 1969 | rowspan=2|13.10(3) s | IT | 81Kr | rowspan=2|1/2− | rowspan=2| | rowspan=2| |- | EC (0.0025%) | 81Br |-id=Krypton-82 | 82Kr | style="text-align:right" | 36 | style="text-align:right" | 46 | 81.9134811537(59) | style="text-align:center" | 1920 | colspan=3 align=center|Stable | 0+ | 0.11593(31) | |-id=Krypton-83 | 83KrFission product | style="text-align:right" | 36 | style="text-align:right" | 47 | 82.914126516(9) | style="text-align:center" | 1920 | colspan=3 align=center|Stable | 9/2+ | 0.11500(19) | |-id=Krypton-83m1 | style="text-indent:1em" | 83m1Kr | colspan="3" style="text-indent:2em" | 9.4053(8) keV | style="text-align:center" | 1963 | 156.8(5) ns | IT | 83Kr | 7/2+
|-id=Krypton-83m2 | style="text-indent:1em" | 83m2Kr | colspan="3" style="text-indent:2em" | 41.5575(7) keV | style="text-align:center" | 1940 | 1.830(13) h | IT | 83Kr | 1/2−
|-id=Krypton-84 | 84Kr | style="text-align:right" | 36 | style="text-align:right" | 48 | 83.9114977271(41) | style="text-align:center" | 1920 | colspan=3 align=center|Stable | 0+ | 0.56987(15) | |-id=Krypton-84m | style="text-indent:1em" | 84mKr | colspan="3" style="text-indent:2em" | 3236.07(18) keV | style="text-align:center" | 1977 | 1.83(4) μs | IT | 84Kr | 8+
|-id=Krypton-85 | 85Kr | style="text-align:right" | 36 | style="text-align:right" | 49 | 84.9125273(21) | style="text-align:center" | 1943 | 10.728(7) y | β− | 85Rb | 9/2+
|-id=Krypton-85m1 | rowspan=2 style="text-indent:1em" | 85m1Kr | rowspan=2 colspan="3" style="text-indent:2em" | 304.871(20) keV | rowspan=2 style="text-align:center" | 1947 | rowspan=2|4.480(8) h | β− (78.8%) | 85Rb | rowspan=2|1/2− | rowspan=2| | rowspan=2| |- | IT (21.2%) | 85Kr |-id=Krypton-85m2 | style="text-indent:1em" | 85m2Kr | colspan="3" style="text-indent:2em" | 1991.8(2) keV | style="text-align:center" | 1989 | 1.82(5) μs | IT | 85Kr | (17/2+)
|-id=Krypton-86 | 86KrFormerly used to define the meter | style="text-align:right" | 36 | style="text-align:right" | 50 | 85.9106106247(40) | style="text-align:center" | 1920 | colspan=3 align=center|Observationally StableBelieved to decay by β−β− to 86Sr | 0+ | 0.17279(41) | |-id=Krypton-87 | 87Kr | style="text-align:right" | 36 | style="text-align:right" | 51 | 86.91335476(26) | style="text-align:center" | 1943 | 76.3(5) min | β− | 87Rb | 5/2+
|-id=Krypton-88 | 88Kr | style="text-align:right" | 36 | style="text-align:right" | 52 | 87.9144479(28) | style="text-align:center" | 1939 | 2.825(19) h | β− | 88Rb | 0+
|-id=Krypton-89 | 89Kr | style="text-align:right" | 36 | style="text-align:right" | 53 | 88.9178354(23) | style="text-align:center" | 1943 | 3.15(4) min | β− | 89Rb | 3/2+
|-id=Krypton-90 | 90Kr | style="text-align:right" | 36 | style="text-align:right" | 54 | 89.9195279(20) | style="text-align:center" | 1951 | 32.32(9) s | β− | 90mRb | 0+
|-id=Krypton-91 | rowspan=2|91Kr | rowspan=2 style="text-align:right" | 36 | rowspan=2 style="text-align:right" | 55 | rowspan=2|90.9238063(24) | rowspan=2 style="text-align:center" | 1951 | rowspan=2|8.57(4) s | β− | 91Rb | rowspan=2|5/2+ | rowspan=2| | rowspan=2| |- | β−, n? | 90Rb |-id=Krypton-92 | rowspan=2|92Kr | rowspan=2 style="text-align:right" | 36 | rowspan=2 style="text-align:right" | 56 | rowspan=2|91.9261731(29) | rowspan=2 style="text-align:center" | 1951 | rowspan=2|1.840(8) s | β− (99.97%) | 92Rb | rowspan=2|0+ | rowspan=2| | rowspan=2| |- | β−, n (0.0332%) | 91Rb |-id=Krypton-93 | rowspan=2|93Kr | rowspan=2 style="text-align:right" | 36 | rowspan=2 style="text-align:right" | 57 | rowspan=2|92.9311472(27) | rowspan=2 style="text-align:center" | 1951 | rowspan=2|1.287(10) s | β− (98.05%) | 93Rb | rowspan=2|1/2+ | rowspan=2| | rowspan=2| |- | β−, n (1.95%) | 92Rb |-id=Krypton-94 | rowspan=2|94Kr | rowspan=2 style="text-align:right" | 36 | rowspan=2 style="text-align:right" | 58 | rowspan=2|93.934140(13) | rowspan=2 style="text-align:center" | 1972 | rowspan=2|212(4) ms | β− (98.89%) | 94Rb | rowspan=2|0+ | rowspan=2| | rowspan=2| |- | β−, n (1.11%) | 93Rb |-id=Krypton-95 | rowspan=3|95Kr | rowspan=3 style="text-align:right" | 36 | rowspan=3 style="text-align:right" | 59 | rowspan=3|94.939711(20) | rowspan=3 style="text-align:center" | 1994 | rowspan=3|114(3) ms | β− (97.13%) | 95Rb | rowspan=3|1/2+ | rowspan=3| | rowspan=3| |- | β−, n (2.87%) | 94Rb |- | β−, 2n? | 93Rb |-id=Krypton-95m | style="text-indent:1em" | 95mKr | colspan="3" style="text-indent:2em" | 195.5(3) keV | style="text-align:center" | 2006 | 1.582(22) μs | IT | 95Kr | (7/2+)
|-id=Krypton-96 | rowspan=2|96Kr | rowspan=2 style="text-align:right" | 36 | rowspan=2 style="text-align:right" | 60 | rowspan=2|95.942998(62) | rowspan=2 style="text-align:center" | 1994 | rowspan=2|80(8) ms | β− (96.3%) | 96Rb | rowspan=2|0+ | rowspan=2| | rowspan=2| |- | β−, n (3.7%) | 95Rb |-id=Krypton-97 | rowspan=3|97Kr | rowspan=3 style="text-align:right" | 36 | rowspan=3 style="text-align:right" | 61 | rowspan=3|96.94909(14) | rowspan=3 style="text-align:center" | 1997 | rowspan=3|62.2(32) ms | β− (93.3%) | 97Rb | rowspan=3|3/2+# | rowspan=3| | rowspan=3| |- | β−, n (6.7%) | 96Rb |- | β−, 2n? | 95Rb |-id=Krypton-98 | rowspan=3|98Kr | rowspan=3 style="text-align:right" | 36 | rowspan=3 style="text-align:right" | 62 | rowspan=3|97.95264(32)# | rowspan=3 style="text-align:center" | 1997 | rowspan=3|42.8(36) ms | β− (93.0%) | 98Rb | rowspan=3|0+ | rowspan=3| | rowspan=3| |- | β−, n (7.0%) | 97Rb |- | β−, 2n? | 96Rb |-id=Krypton-99 | rowspan=3|99Kr | rowspan=3 style="text-align:right" | 36 | rowspan=3 style="text-align:right" | 63 | rowspan=3|98.95878(43)# | rowspan=3 style="text-align:center" | 1997 | rowspan=3|40(11) ms | β− (89%) | 99Rb | rowspan=3|5/2−# | rowspan=3| | rowspan=3| |- | β−, n (11%) | 98Rb |- | β−, 2n? | 97Rb |-id=Krypton-100 | rowspan=3|100Kr | rowspan=3 style="text-align:right" | 36 | rowspan=3 style="text-align:right" | 64 | rowspan=3|99.96300(43)# | rowspan=3 style="text-align:center" | 1997 | rowspan=3|12(8) ms | β− | 100Rb | rowspan=3|0+ | rowspan=3| | rowspan=3| |- | β−, n? | 99Rb |- | β−, 2n? | 98Rb |-id=Krypton-101 | rowspan=3 | 101Kr | rowspan=3 | 36 | rowspan=3 | 65 | rowspan=3 | 100.96932(54)# | rowspan=3 style="text-align:center" | 2010 | rowspan=3 | 9# ms[>400 ns] | β−? | 101Rb | rowspan=3 | 5/2+# | rowspan=3 | | rowspan=3 | |- | β−, n? | 100Rb |- | β−, 2n? | 99Rb |-id=Krypton-102 | 102Kr | style="text-align:right" | 36 | style="text-align:right" | 66 | |style="text-align:center" | 2021
| 0+
|-id=Krypton-103 | 103Kr | style="text-align:right" | 36 | style="text-align:right" | 67 | |style="text-align:center" | 2024
Notable isotopes
Krypton-81