Isotopes of lanthanum

Naturally occurring lanthanum (57La) is composed of one stable (139La) and one radioactive (138La) isotope, with the stable isotope, 139La, being the most abundant (99.91% natural abundance). There are 39 radioisotopes that have been characterized, with the most stable being 138La, with a half-life of 1.02×1011 years; 137La, with a half-life of 60,000 years and 140La, with a half-life of 1.6781 days. The remaining radioactive isotopes have half-lives that are less than a day and the majority of these have half-lives that are less than 1 minute. This element also has 12 nuclear isomers, the longest-lived of which is 132mLa, with a half-life of 24.3 minutes. Lighter isotopes mostly decay to isotopes of barium and heavy ones mostly decay to isotopes of cerium. 138La can decay to both.

The isotopes of lanthanum range in atomic weight from 115.96 u (116La) to 154.96 u (155La).

List of isotopes

 * rowspan=2|116La
 * rowspan=2 style="text-align:right" | 57
 * rowspan=2 style="text-align:right" | 59
 * rowspan=2|
 * rowspan=2|50(22) ms
 * p (~60%)
 * 115Ba
 * rowspan=2|
 * rowspan=2|
 * rowspan=2|
 * β+ (~40%)
 * 116Ba
 * rowspan=2|117La
 * rowspan=2 style="text-align:right" | 57
 * rowspan=2 style="text-align:right" | 60
 * rowspan=2|116.95007(43)#
 * rowspan=2|23.5(26) ms
 * β+
 * 117Ba
 * rowspan=2|(3/2+, 3/2−)
 * rowspan=2|
 * rowspan=2|
 * p
 * 116Ba
 * style="text-indent:1em" | 117mLa
 * colspan="3" style="text-indent:2em" | 151(12) keV
 * 10(5) ms
 * (9/2+)
 * 118La
 * style="text-align:right" | 57
 * style="text-align:right" | 61
 * 117.94673(32)#
 * 200# ms
 * β+
 * 118Ba
 * 119La
 * style="text-align:right" | 57
 * style="text-align:right" | 62
 * 118.94099(43)#
 * 1# s
 * β+
 * 119Ba
 * 11/2−#
 * rowspan=2|120La
 * rowspan=2 style="text-align:right" | 57
 * rowspan=2 style="text-align:right" | 63
 * rowspan=2|119.93807(54)#
 * rowspan=2|2.8(2) s
 * β+
 * 120Ba
 * rowspan=2|
 * rowspan=2|
 * rowspan=2|
 * β+, p
 * 119Cs
 * rowspan=2|121La
 * rowspan=2 style="text-align:right" | 57
 * rowspan=2 style="text-align:right" | 64
 * rowspan=2|120.93301(54)#
 * rowspan=2|5.3(2) s
 * β+
 * 121Ba
 * rowspan=2|11/2−#
 * rowspan=2|
 * rowspan=2|
 * β+, p
 * 120Cs
 * rowspan=2|122La
 * rowspan=2 style="text-align:right" | 57
 * rowspan=2 style="text-align:right" | 65
 * rowspan=2|121.93071(32)#
 * rowspan=2|8.6(5) s
 * β+
 * 122Ba
 * rowspan=2|
 * rowspan=2|
 * rowspan=2|
 * β+, p
 * 121Cs
 * 123La
 * style="text-align:right" | 57
 * style="text-align:right" | 66
 * 122.92624(21)#
 * 17(3) s
 * β+
 * 123Ba
 * 11/2−#
 * 124La
 * style="text-align:right" | 57
 * style="text-align:right" | 67
 * 123.92457(6)
 * 29.21(17) s
 * β+
 * 124Ba
 * (7−, 8−)
 * style="text-indent:1em" | 124mLa
 * colspan="3" style="text-indent:2em" | 100(100)# keV
 * 21(4) s
 * low(+#)
 * 125La
 * style="text-align:right" | 57
 * style="text-align:right" | 68
 * 124.920816(28)
 * 64.8(12) s
 * β+
 * 125Ba
 * (11/2−)
 * style="text-indent:1em" | 125mLa
 * colspan="3" style="text-indent:2em" | 107.0(10) keV
 * 390(40) ms
 * (3/2+)
 * 126La
 * style="text-align:right" | 57
 * style="text-align:right" | 69
 * 125.91951(10)
 * 54(2) s
 * β+
 * 126Ba
 * (5)(+#)
 * style="text-indent:1em" | 126mLa
 * colspan="3" style="text-indent:2em" | 210(410) keV
 * 20(20) s
 * (0−, 1−, 2−)
 * 127La
 * style="text-align:right" | 57
 * style="text-align:right" | 70
 * 126.916375(28)
 * 5.1(1) min
 * β+
 * 127Ba
 * (11/2−)
 * rowspan=2 style="text-indent:1em" | 127mLa
 * rowspan=2 colspan="3" style="text-indent:2em" | 14.8(12) keV
 * rowspan=2|3.7(4) min
 * β+
 * 127Ba
 * rowspan=2|(3/2+)
 * rowspan=2|
 * rowspan=2|
 * IT
 * 127La
 * 128La
 * style="text-align:right" | 57
 * style="text-align:right" | 71
 * 127.91559(6)
 * 5.18(14) min
 * β+
 * 128Ba
 * (5+)
 * style="text-indent:1em" | 128mLa
 * colspan="3" style="text-indent:2em" | 100(100)# keV
 * <1.4 min
 * IT
 * 128La
 * (1+, 2−)
 * 129La
 * style="text-align:right" | 57
 * style="text-align:right" | 72
 * 128.912693(22)
 * 11.6(2) min
 * β+
 * 129Ba
 * 3/2+
 * style="text-indent:1em" | 129mLa
 * colspan="3" style="text-indent:2em" | 172.1(4) keV
 * 560(50) ms
 * IT
 * 129La
 * 11/2−
 * 130La
 * style="text-align:right" | 57
 * style="text-align:right" | 73
 * 129.912369(28)
 * 8.7(1) min
 * β+
 * 130Ba
 * 3(+)
 * 131La
 * style="text-align:right" | 57
 * style="text-align:right" | 74
 * 130.91007(3)
 * 59(2) min
 * β+
 * 131Ba
 * 3/2+
 * style="text-indent:1em" | 131mLa
 * colspan="3" style="text-indent:2em" | 304.52(24) keV
 * 170(10) μs
 * 11/2−
 * 132La
 * style="text-align:right" | 57
 * style="text-align:right" | 75
 * 131.91010(4)
 * 4.8(2) h
 * β+
 * 132Ba
 * 2−
 * rowspan=2 style="text-indent:1em" | 132mLa
 * rowspan=2 colspan="3" style="text-indent:2em" | 188.18(11) keV
 * rowspan=2|24.3(5) min
 * IT (76%)
 * 132La
 * rowspan=2|6−
 * rowspan=2|
 * rowspan=2|
 * β+ (24%)
 * 132Ba
 * 133La
 * style="text-align:right" | 57
 * style="text-align:right" | 76
 * 132.90822(3)
 * 3.912(8) h
 * β+
 * 133Ba
 * 5/2+
 * 134La
 * style="text-align:right" | 57
 * style="text-align:right" | 77
 * 133.908514(21)
 * 6.45(16) min
 * β+
 * 134Ba
 * 1+
 * 135La
 * style="text-align:right" | 57
 * style="text-align:right" | 78
 * 134.906977(11)
 * 19.5(2) h
 * β+
 * 135Ba
 * 5/2+
 * 136La
 * style="text-align:right" | 57
 * style="text-align:right" | 79
 * 135.90764(6)
 * 9.87(3) min
 * β+
 * 136Ba
 * 1+
 * style="text-indent:1em" | 136mLa
 * colspan="3" style="text-indent:2em" | 255(9) keV
 * 114(3) ms
 * IT
 * 136La
 * (8)(−#)
 * 137La
 * style="text-align:right" | 57
 * style="text-align:right" | 80
 * 136.906494(14)
 * 6(2)×104 y
 * EC
 * 137Ba
 * 7/2+
 * extinct
 * rowspan=2|138La
 * rowspan=2 style="text-align:right" | 57
 * rowspan=2 style="text-align:right" | 81
 * rowspan=2|137.907112(4)
 * rowspan=2|1.02(1)×1011 y
 * β+ (66.4%)
 * 138Ba
 * rowspan=2|5+
 * rowspan=2|9.0(1)×10−4
 * rowspan=2|
 * β− (33.6%)
 * 138Ce
 * style="text-indent:1em" | 138mLa
 * colspan="3" style="text-indent:2em" | 72.57(3) keV
 * 116(5) ns
 * (3)+
 * 139La
 * style="text-align:right" | 57
 * style="text-align:right" | 82
 * 138.9063533(26)
 * colspan=3 align=center|Stable
 * 7/2+
 * 0.99910(1)
 * 140La
 * style="text-align:right" | 57
 * style="text-align:right" | 83
 * 139.9094776(26)
 * 1.6781(3) d
 * β−
 * 140Ce
 * 3−
 * 141La
 * style="text-align:right" | 57
 * style="text-align:right" | 84
 * 140.910962(5)
 * 3.92(3) h
 * β−
 * 141Ce
 * (7/2+)
 * 142La
 * style="text-align:right" | 57
 * style="text-align:right" | 85
 * 141.914079(6)
 * 91.1(5) min
 * β−
 * 142Ce
 * 2−
 * 143La
 * style="text-align:right" | 57
 * style="text-align:right" | 86
 * 142.916063(17)
 * 14.2(1) min
 * β−
 * 143Ce
 * (7/2)+
 * 144La
 * style="text-align:right" | 57
 * style="text-align:right" | 87
 * 143.91960(5)
 * 40.8(4) s
 * β−
 * 144Ce
 * (3−)
 * 145La
 * style="text-align:right" | 57
 * style="text-align:right" | 88
 * 144.92165(10)
 * 24.8(20) s
 * β−
 * 145Ce
 * (5/2+)
 * rowspan=2|146La
 * rowspan=2 style="text-align:right" | 57
 * rowspan=2 style="text-align:right" | 89
 * rowspan=2|145.92579(8)
 * rowspan=2|6.27(10) s
 * β− (99.99%)
 * 146Ce
 * rowspan=2|2−
 * rowspan=2|
 * rowspan=2|
 * β−, n (.007%)
 * 145Ce
 * style="text-indent:1em" | 146mLa
 * colspan="3" style="text-indent:2em" | 130(130) keV
 * 10.0(1) s
 * β−
 * 146Ce
 * (6−)
 * rowspan=2|147La
 * rowspan=2 style="text-align:right" | 57
 * rowspan=2 style="text-align:right" | 90
 * rowspan=2|146.92824(5)
 * rowspan=2|4.015(8) s
 * β− (99.96%)
 * 147Ce
 * rowspan=2|(5/2+)
 * rowspan=2|
 * rowspan=2|
 * β−, n (.04%)
 * 146Ce
 * rowspan=2|148La
 * rowspan=2 style="text-align:right" | 57
 * rowspan=2 style="text-align:right" | 91
 * rowspan=2|147.93223(6)
 * rowspan=2|1.26(8) s
 * β− (99.85%)
 * 148Ce
 * rowspan=2|(2−)
 * rowspan=2|
 * rowspan=2|
 * β−, n (.15%)
 * 147Ce
 * rowspan=2|149La
 * rowspan=2 style="text-align:right" | 57
 * rowspan=2 style="text-align:right" | 92
 * rowspan=2|148.93473(34)#
 * rowspan=2|1.05(3) s
 * β− (98.6%)
 * 149Ce
 * rowspan=2|5/2+#
 * rowspan=2|
 * rowspan=2|
 * β−, n (1.4%)
 * 148Ce
 * rowspan=2|150La
 * rowspan=2 style="text-align:right" | 57
 * rowspan=2 style="text-align:right" | 93
 * rowspan=2|149.93877(43)#
 * rowspan=2|510(30) ms
 * β− (97.3%)
 * 150Ce
 * rowspan=2|(3+)
 * rowspan=2|
 * rowspan=2|
 * β−, n (2.7%)
 * 149Ce
 * 151La
 * style="text-align:right" | 57
 * style="text-align:right" | 94
 * 150.94172(43)#
 * 300# ms [>300 ns]
 * β−
 * 151Ce
 * 5/2+#
 * 152La
 * style="text-align:right" | 57
 * style="text-align:right" | 95
 * 151.94625(43)#
 * 200# ms [>300 ns]
 * β−
 * 152Ce
 * 153La
 * style="text-align:right" | 57
 * style="text-align:right" | 96
 * 152.94962(64)#
 * 150# ms [>300 ns]
 * β−
 * 153Ce
 * 5/2+#
 * 154La
 * style="text-align:right" | 57
 * style="text-align:right" | 97
 * 153.95450(64)#
 * 100# ms
 * β−
 * 154Ce
 * 155La
 * style="text-align:right" | 57
 * style="text-align:right" | 98
 * 154.95835(86)#
 * 60# ms
 * β−
 * 155Ce
 * 5/2+#
 * 144La
 * style="text-align:right" | 57
 * style="text-align:right" | 87
 * 143.91960(5)
 * 40.8(4) s
 * β−
 * 144Ce
 * (3−)
 * 145La
 * style="text-align:right" | 57
 * style="text-align:right" | 88
 * 144.92165(10)
 * 24.8(20) s
 * β−
 * 145Ce
 * (5/2+)
 * rowspan=2|146La
 * rowspan=2 style="text-align:right" | 57
 * rowspan=2 style="text-align:right" | 89
 * rowspan=2|145.92579(8)
 * rowspan=2|6.27(10) s
 * β− (99.99%)
 * 146Ce
 * rowspan=2|2−
 * rowspan=2|
 * rowspan=2|
 * β−, n (.007%)
 * 145Ce
 * style="text-indent:1em" | 146mLa
 * colspan="3" style="text-indent:2em" | 130(130) keV
 * 10.0(1) s
 * β−
 * 146Ce
 * (6−)
 * rowspan=2|147La
 * rowspan=2 style="text-align:right" | 57
 * rowspan=2 style="text-align:right" | 90
 * rowspan=2|146.92824(5)
 * rowspan=2|4.015(8) s
 * β− (99.96%)
 * 147Ce
 * rowspan=2|(5/2+)
 * rowspan=2|
 * rowspan=2|
 * β−, n (.04%)
 * 146Ce
 * rowspan=2|148La
 * rowspan=2 style="text-align:right" | 57
 * rowspan=2 style="text-align:right" | 91
 * rowspan=2|147.93223(6)
 * rowspan=2|1.26(8) s
 * β− (99.85%)
 * 148Ce
 * rowspan=2|(2−)
 * rowspan=2|
 * rowspan=2|
 * β−, n (.15%)
 * 147Ce
 * rowspan=2|149La
 * rowspan=2 style="text-align:right" | 57
 * rowspan=2 style="text-align:right" | 92
 * rowspan=2|148.93473(34)#
 * rowspan=2|1.05(3) s
 * β− (98.6%)
 * 149Ce
 * rowspan=2|5/2+#
 * rowspan=2|
 * rowspan=2|
 * β−, n (1.4%)
 * 148Ce
 * rowspan=2|150La
 * rowspan=2 style="text-align:right" | 57
 * rowspan=2 style="text-align:right" | 93
 * rowspan=2|149.93877(43)#
 * rowspan=2|510(30) ms
 * β− (97.3%)
 * 150Ce
 * rowspan=2|(3+)
 * rowspan=2|
 * rowspan=2|
 * β−, n (2.7%)
 * 149Ce
 * 151La
 * style="text-align:right" | 57
 * style="text-align:right" | 94
 * 150.94172(43)#
 * 300# ms [>300 ns]
 * β−
 * 151Ce
 * 5/2+#
 * 152La
 * style="text-align:right" | 57
 * style="text-align:right" | 95
 * 151.94625(43)#
 * 200# ms [>300 ns]
 * β−
 * 152Ce
 * 153La
 * style="text-align:right" | 57
 * style="text-align:right" | 96
 * 152.94962(64)#
 * 150# ms [>300 ns]
 * β−
 * 153Ce
 * 5/2+#
 * 154La
 * style="text-align:right" | 57
 * style="text-align:right" | 97
 * 153.95450(64)#
 * 100# ms
 * β−
 * 154Ce
 * 155La
 * style="text-align:right" | 57
 * style="text-align:right" | 98
 * 154.95835(86)#
 * 60# ms
 * β−
 * 155Ce
 * 5/2+#
 * 152Ce
 * 153La
 * style="text-align:right" | 57
 * style="text-align:right" | 96
 * 152.94962(64)#
 * 150# ms [>300 ns]
 * β−
 * 153Ce
 * 5/2+#
 * 154La
 * style="text-align:right" | 57
 * style="text-align:right" | 97
 * 153.95450(64)#
 * 100# ms
 * β−
 * 154Ce
 * 155La
 * style="text-align:right" | 57
 * style="text-align:right" | 98
 * 154.95835(86)#
 * 60# ms
 * β−
 * 155Ce
 * 5/2+#
 * 155La
 * style="text-align:right" | 57
 * style="text-align:right" | 98
 * 154.95835(86)#
 * 60# ms
 * β−
 * 155Ce
 * 5/2+#
 * β−
 * 155Ce
 * 5/2+#