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Isotopes of lanthanum



Naturally occurring Lanthanum (La) is composed of one stable (139La) and one radioactive (138La) isotope, with the stable isotope, 139La, being the most abundant (99.91% natural abundance). 38 radioisotopes have been characterized with the most stable being 138La with a half-life of 105×109 years, and 137La with a half-life of 60,000 years. Most of the remaining radioactive isotopes have half-lives that are less than 24 hours and the majority of these have half lives that are less than 1 minute. This element also has 3 meta states.

Additional recommended knowledge

The isotopes of lanthanum range in atomic weight from 117 u (117La) to 155 u (155La).
Standard atomic mass: 138.90547(7) u

Table

nuclide
symbol
Z(p) N(n)  
isotopic mass (u)
 
half-life nuclear
spin
representative
isotopic
composition
(mole fraction)
range of natural
variation
(mole fraction)
excitation energy
117La 57 60 116.95007(43)# 23.5(26) ms (3/2+,3/2-)
117mLa 151(12) keV 10(5) ms (9/2+)
118La 57 61 117.94673(32)# 200# ms
119La 57 62 118.94099(43)# 1# s 11/2-#
120La 57 63 119.93807(54)# 2.8(2) s
121La 57 64 120.93301(54)# 5.3(2) s 11/2-#
122La 57 65 121.93071(32)# 8.6(5) s
123La 57 66 122.92624(21)# 17(3) s 11/2-#
124La 57 67 123.92457(6) 29.21(17) s (7-,8-)
124mLa 100(100)# keV 21(4) s low(+#)
125La 57 68 124.920816(28) 64.8(12) s (11/2-)
125mLa 107.0(10) keV 390(40) ms (3/2+)
126La 57 69 125.91951(10) 54(2) s (5)(+#)
126mLa 210(410) keV 20(20) s (0-,1-,2-)
127La 57 70 126.916375(28) 5.1(1) min (11/2-)
127mLa 14.8(12) keV 3.7(4) min (3/2+)
128La 57 71 127.91559(6) 5.18(14) min (5+)
128mLa 100(100)# keV <1.4 min (1+,2-)
129La 57 72 128.912693(22) 11.6(2) min 3/2+
129mLa 172.1(4) keV 560(50) ms 11/2-
130La 57 73 129.912369(28) 8.7(1) min 3(+)
131La 57 74 130.91007(3) 59(2) min 3/2+
131mLa 304.52(24) keV 170(10) µs 11/2-
132La 57 75 131.91010(4) 4.8(2) h 2-
132mLa 188.18(11) keV 24.3(5) min 6-
133La 57 76 132.90822(3) 3.912(8) h 5/2+
134La 57 77 133.908514(21) 6.45(16) min 1+
135La 57 78 134.906977(11) 19.5(2) h 5/2+
136La 57 79 135.90764(6) 9.87(3) min 1+
136mLa 255(9) keV 114(3) ms (8)(-#)
137La 57 80 136.906494(14) 6(2)E+4 a 7/2+
138La 57 81 137.907112(4) 1.02(1)E+11 a 5+ 0.00090(1)
138mLa 72.57(3) keV 116(5) ns (3)+
139La 57 82 138.9063533(26) STABLE 7/2+ 0.99910(1)
140La 57 83 139.9094776(26) 1.6781(3) d 3-
141La 57 84 140.910962(5) 3.92(3) h (7/2+)
142La 57 85 141.914079(6) 91.1(5) min 2-
143La 57 86 142.916063(17) 14.2(1) min (7/2)+
144La 57 87 143.91960(5) 40.8(4) s (3-)
145La 57 88 144.92165(10) 24.8(20) s (5/2+)
146La 57 89 145.92579(8) 6.27(10) s 2-
146mLa 130(130) keV 10.0(1) s (6-)
147La 57 90 146.92824(5) 4.015(8) s (5/2+)
148La 57 91 147.93223(6) 1.26(8) s (2-)
149La 57 92 148.93473(34)# 1.05(3) s 5/2+#
150La 57 93 149.93877(43)# 510(30) ms (3+)
151La 57 94 150.94172(43)# 300# ms [>300 ns] 5/2+#
152La 57 95 151.94625(43)# 200# ms [>300 ns]
153La 57 96 152.94962(64)# 150# ms [>300 ns] 5/2+#
154La 57 97 153.95450(64)# 100# ms
155La 57 98 154.95835(86)# 60# ms 5/2+#

Notes

  • Geologically exceptional samples are known in which the isotopic composition lies outside the reported range. The uncertainty in the atomic mass may exceed the stated value for such specimens.
  • Values marked # are not purely derived from experimental data, but at least partly from systematic trends. Spins with weak assignment arguments are enclosed in parentheses.
  • Uncertainties are given in concise form in parentheses after the corresponding last digits. Uncertainty values denote one standard deviation, except isotopic composition and standard atomic mass from IUPAC which use expanded uncertainties.

References

  • Isotope masses from Ame2003 Atomic Mass Evaluation by G. Audi, A.H. Wapstra, C. Thibault, J. Blachot and O. Bersillon in Nuclear Physics A729 (2003).
  • Isotopic compositions and standard atomic masses from Atomic weights of the elements. Review 2000 (IUPAC Technical Report). Pure Appl. Chem. Vol. 75, No. 6, pp. 683-800, (2003) and Atomic Weights Revised (2005).
  • Half-life, spin, and isomer data selected from these sources. Editing notes on this article's talk page.
    • Audi, Bersillon, Blachot, Wapstra. The Nubase2003 evaluation of nuclear and decay properties, Nuc. Phys. A 729, pp. 3-128 (2003).
    • National Nuclear Data Center, Brookhaven National Laboratory. Information extracted from the NuDat 2.1 database (retrieved Sept. 2005).
    • David R. Lide (ed.), Norman E. Holden in CRC Handbook of Chemistry and Physics, 85th Edition, online version. CRC Press. Boca Raton, Florida (2005). Section 11, Table of the Isotopes.


Isotopes of barium Isotopes of lanthanum Isotopes of cerium
Index to isotope pages
 
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Isotopes_of_lanthanum". A list of authors is available in Wikipedia.
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