Isotopes of arsenic

Arsenic (33As) has 32 known isotopes and at least 10 isomers. Only one of these isotopes, 75As, is stable; as such, it is considered a monoisotopic element. The longest-lived radioisotope is 73As with a half-life of 80 days.

List of isotopes

 * rowspan=2 |64As
 * rowspan=2 style="text-align:right" | 33
 * rowspan=2 style="text-align:right" | 31
 * rowspan=2 |63.95756(22)#
 * rowspan=2 |69.0(14) ms
 * β+
 * 64Ge
 * rowspan=2 |0+#
 * rowspan=2 |
 * β+, p?
 * 63Ga
 * rowspan=2 |65As
 * rowspan=2 style="text-align:right" | 33
 * rowspan=2 style="text-align:right" | 32
 * rowspan=2 |64.949611(91)
 * rowspan=2 |130.3(6) ms
 * β+
 * 65Ge
 * rowspan=2 |3/2−#
 * rowspan=2 |
 * β+, p?
 * 64Ga
 * 66As
 * style="text-align:right" | 33
 * style="text-align:right" | 33
 * 65.9441488(61)
 * 95.77(23) ms
 * β+
 * 66Ge
 * 0+
 * style="text-indent:1em" | 66m1As
 * colspan="3" style="text-indent:2em" | 1356.63(17) keV
 * 1.14(4) μs
 * IT
 * 66As
 * 5+
 * style="text-indent:1em" | 66m2As
 * colspan="3" style="text-indent:2em" | 3023.(3) keV
 * 7.98(26) μs
 * IT
 * 66As
 * 9+
 * 67As
 * style="text-align:right" | 33
 * style="text-align:right" | 34
 * 66.93925111(48)
 * 42.5(12) s
 * β+
 * 67Ge
 * (5/2−)
 * 68As
 * style="text-align:right" | 33
 * style="text-align:right" | 35
 * 67.9367741(20)
 * 151.6(8) s
 * β+
 * 68Ge
 * 3+
 * style="text-indent:1em" | 68mAs
 * colspan="3" style="text-indent:2em" | 425.1(2) keV
 * 111(20) ns
 * IT
 * 68As
 * 1+
 * 69As
 * style="text-align:right" | 33
 * style="text-align:right" | 36
 * 68.932246(34)
 * 15.2(2) min
 * β+
 * 69Ge
 * 5/2−
 * 70As
 * style="text-align:right" | 33
 * style="text-align:right" | 37
 * 69.9309346(15)
 * 52.6(3) min
 * β+
 * 70Ge
 * 4+
 * style="text-indent:1em" | 70mAs
 * colspan="3" style="text-indent:2em" | 32.046(23) keV
 * 96(3) μs
 * IT
 * 70As
 * 2+
 * 71As
 * style="text-align:right" | 33
 * style="text-align:right" | 38
 * 70.9271136(45)
 * 65.30(7) h
 * β+
 * 71Ge
 * 5/2−
 * 72As
 * style="text-align:right" | 33
 * style="text-align:right" | 39
 * 71.9267523(44)
 * 26.0(1) h
 * β+
 * 72Ge
 * 2−
 * 73As
 * style="text-align:right" | 33
 * style="text-align:right" | 40
 * 72.9238291(41)
 * 80.30(6) d
 * EC
 * 73Ge
 * 3/2−
 * style="text-indent:1em" | 73mAs
 * colspan="3" style="text-indent:2em" | 427.902(21) keV
 * 5.7(2) μs
 * IT
 * 73As
 * 9/2+
 * rowspan=2|74As
 * rowspan=2 style="text-align:right" | 33
 * rowspan=2 style="text-align:right" | 41
 * rowspan=2|73.9239286(18)
 * rowspan=2|17.77(2) d
 * β+ (66%)
 * 74Ge
 * rowspan=2|2−
 * rowspan=2|
 * β− (34%)
 * 74Se
 * 75As
 * style="text-align:right" | 33
 * style="text-align:right" | 42
 * 74.92159456(95)
 * colspan=3 align=center|Stable
 * 3/2−
 * 1.0000
 * style="text-indent:1em" | 75mAs
 * colspan="3" style="text-indent:2em" | 303.9243(8) keV
 * 17.62(23) ms
 * IT
 * 75As
 * 9/2+
 * 76As
 * style="text-align:right" | 33
 * style="text-align:right" | 43
 * 75.92239201(95)
 * 1.0933(38) d
 * β−
 * 76Se
 * 2−
 * style="text-indent:1em" | 76mAs
 * colspan="3" style="text-indent:2em" | 44.425(1) keV
 * 1.84(6) μs
 * IT
 * 76As
 * (1)+
 * 77As
 * style="text-align:right" | 33
 * style="text-align:right" | 44
 * 76.9206476(18)
 * 38.79(5) h
 * β−
 * 77Se
 * 3/2−
 * style="text-indent:1em" | 77mAs
 * colspan="3" style="text-indent:2em" | 475.48(4) keV
 * 114.0(25) μs
 * IT
 * 77As
 * 9/2+
 * 78As
 * style="text-align:right" | 33
 * style="text-align:right" | 45
 * 77.921828(10)
 * 90.7(2) min
 * β−
 * 78Se
 * 2−
 * 79As
 * style="text-align:right" | 33
 * style="text-align:right" | 46
 * 78.9209484(57)
 * 9.01(15) min
 * β−
 * 79Se
 * 3/2−
 * style="text-indent:1em" | 79mAs
 * colspan="3" style="text-indent:2em" | 772.81(6) keV
 * 1.21(1) μs
 * IT
 * 79As
 * (9/2)+
 * 80As
 * style="text-align:right" | 33
 * style="text-align:right" | 47
 * 79.9224744(36)
 * 15.2(2) s
 * β−
 * 80Se
 * 1+
 * 81As
 * style="text-align:right" | 33
 * style="text-align:right" | 48
 * 80.9221323(28)
 * 33.3(8) s
 * β−
 * 81Se
 * 3/2−
 * 82As
 * style="text-align:right" | 33
 * style="text-align:right" | 49
 * 81.9247387(40)
 * 19.1(5) s
 * β−
 * 82Se
 * (2−)
 * style="text-indent:1em" | 82mAs
 * colspan="3" style="text-indent:2em" | 131.6(5) keV
 * 13.6(4) s
 * β−
 * 82Se
 * (5-)
 * 83As
 * style="text-align:right" | 33
 * style="text-align:right" | 50
 * 82.9252069(30)
 * 13.4(4) s
 * β−
 * 83Se
 * 5/2−#
 * rowspan=2|84As
 * rowspan=2 style="text-align:right" | 33
 * rowspan=2 style="text-align:right" | 51
 * rowspan=2|83.9293033(34)
 * rowspan=2|3.16(58) s
 * β− (99.72%)
 * 84Se
 * rowspan=2|(2−)
 * rowspan=2|
 * β−, n (.28%)
 * 83Se
 * rowspan=2|85As
 * rowspan=2 style="text-align:right" | 33
 * rowspan=2 style="text-align:right" | 52
 * rowspan=2|84.9321637(33)
 * rowspan=2|2.022(7) s
 * β−, n (62.6%)
 * 84Se
 * rowspan=2|(5/2−)
 * rowspan=2|
 * β− (37.4%)
 * 85Se
 * rowspan=3|86As
 * rowspan=3 style="text-align:right" | 33
 * rowspan=3 style="text-align:right" | 53
 * rowspan=3|85.9367015(37)
 * rowspan=3|945(8) ms
 * β− (64.5%)
 * 86Se
 * rowspan=3|(1−,2−)
 * rowspan=3|
 * β−, n (35.5%)
 * 85Se
 * β−, 2n?
 * 84Se
 * rowspan=3|87As
 * rowspan=3 style="text-align:right" | 33
 * rowspan=3 style="text-align:right" | 54
 * rowspan=3|86.9402917(32)
 * rowspan=3|492(25) ms
 * β− (84.6%)
 * 87Se
 * rowspan=3|(5/2−,3/2−)
 * rowspan=3|
 * β−, n (15.4%)
 * 86Se
 * β−, 2n?
 * 85Se
 * rowspan=2|88As
 * rowspan=2 style="text-align:right" | 33
 * rowspan=2 style="text-align:right" | 55
 * rowspan=2|87.94584(22)#
 * rowspan=2|270(150) ms
 * β−
 * 88Se
 * rowspan=2|
 * rowspan=2|
 * β−, n?
 * 87Se
 * rowspan=3|89As
 * rowspan=3 style="text-align:right" | 33
 * rowspan=3 style="text-align:right" | 56
 * rowspan=3|88.95005(32)#
 * rowspan=3|220# ms [>150 ns]
 * β−?
 * 89Se
 * rowspan=3|5/2−#
 * rowspan=3|
 * β−, n?
 * 88Se
 * β−, 2n?
 * 87Se
 * rowspan=3|90As
 * rowspan=3 style="text-align:right" | 33
 * rowspan=3 style="text-align:right" | 57
 * rowspan=3|89.95600(43)#
 * rowspan=3|70# ms [>300 ns]
 * β−?
 * 90Se
 * rowspan=3|
 * rowspan=3|
 * β−, n?
 * 89Se
 * β−, 2n?
 * 88Se
 * style="text-indent:1em" | 90mAs
 * colspan="3" style="text-indent:2em" | 124.5(5) keV
 * 220(100) ns
 * IT
 * 90As
 * rowspan=3|91As
 * rowspan=3 style="text-align:right" | 33
 * rowspan=3 style="text-align:right" | 58
 * rowspan=3|90.96082(43)#
 * rowspan=3|100# ms [>300 ns]
 * β−?
 * 91Se
 * rowspan=3|5/2−#
 * rowspan=3|
 * β−, n?
 * 90Se
 * β−, 2n?
 * 89Se
 * rowspan=3|92As
 * rowspan=3 style="text-align:right" | 33
 * rowspan=3 style="text-align:right" | 59
 * rowspan=3|91.96739(54)#
 * rowspan=3|45# ms [>300 ns]
 * β−?
 * 92Se
 * rowspan=3|
 * rowspan=3|
 * β−, n?
 * 91Se
 * β−, 2n?
 * 90Se
 * 93As
 * style="text-align:right" | 33
 * style="text-align:right" | 60
 * 94As
 * style="text-align:right" | 33
 * style="text-align:right" | 61
 * 95As
 * style="text-align:right" | 33
 * style="text-align:right" | 62
 * rowspan=2|
 * rowspan=2|
 * β−, n?
 * 87Se
 * rowspan=3|89As
 * rowspan=3 style="text-align:right" | 33
 * rowspan=3 style="text-align:right" | 56
 * rowspan=3|88.95005(32)#
 * rowspan=3|220# ms [>150 ns]
 * β−?
 * 89Se
 * rowspan=3|5/2−#
 * rowspan=3|
 * β−, n?
 * 88Se
 * β−, 2n?
 * 87Se
 * rowspan=3|90As
 * rowspan=3 style="text-align:right" | 33
 * rowspan=3 style="text-align:right" | 57
 * rowspan=3|89.95600(43)#
 * rowspan=3|70# ms [>300 ns]
 * β−?
 * 90Se
 * rowspan=3|
 * rowspan=3|
 * β−, n?
 * 89Se
 * β−, 2n?
 * 88Se
 * style="text-indent:1em" | 90mAs
 * colspan="3" style="text-indent:2em" | 124.5(5) keV
 * 220(100) ns
 * IT
 * 90As
 * rowspan=3|91As
 * rowspan=3 style="text-align:right" | 33
 * rowspan=3 style="text-align:right" | 58
 * rowspan=3|90.96082(43)#
 * rowspan=3|100# ms [>300 ns]
 * β−?
 * 91Se
 * rowspan=3|5/2−#
 * rowspan=3|
 * β−, n?
 * 90Se
 * β−, 2n?
 * 89Se
 * rowspan=3|92As
 * rowspan=3 style="text-align:right" | 33
 * rowspan=3 style="text-align:right" | 59
 * rowspan=3|91.96739(54)#
 * rowspan=3|45# ms [>300 ns]
 * β−?
 * 92Se
 * rowspan=3|
 * rowspan=3|
 * β−, n?
 * 91Se
 * β−, 2n?
 * 90Se
 * 93As
 * style="text-align:right" | 33
 * style="text-align:right" | 60
 * 94As
 * style="text-align:right" | 33
 * style="text-align:right" | 61
 * 95As
 * style="text-align:right" | 33
 * style="text-align:right" | 62
 * rowspan=3|
 * β−, n?
 * 91Se
 * β−, 2n?
 * 90Se
 * 93As
 * style="text-align:right" | 33
 * style="text-align:right" | 60
 * 94As
 * style="text-align:right" | 33
 * style="text-align:right" | 61
 * 95As
 * style="text-align:right" | 33
 * style="text-align:right" | 62
 * 94As
 * style="text-align:right" | 33
 * style="text-align:right" | 61
 * 95As
 * style="text-align:right" | 33
 * style="text-align:right" | 62
 * style="text-align:right" | 61
 * 95As
 * style="text-align:right" | 33
 * style="text-align:right" | 62
 * 95As
 * style="text-align:right" | 33
 * style="text-align:right" | 62
 * 95As
 * style="text-align:right" | 33
 * style="text-align:right" | 62
 * style="text-align:right" | 62