Naturally occurring Erbium (Er) is composed of 6 stable isotopes, Er-162, Er-164, Er-166, Er-167, Er-168, and Er-170 with Er-166 being the most abundant (33.503% natural abundance). 29 radioisotopes have been characterized, with the most stable being Er-169 with a half life of 9.4 days, Er-172 with a half-life of 49.3 hours, Er-160 with a half-life of 28.58 hours, Er-165 with a half-life of 10.36 hours, and Er-171 with a half life of 7.516 hours. All of the remaining radioactive isotopes have half-lifes that are less than 3.5 hours, and the majority of these have half lifes that are less than 4 minutes. This element also has 13 meta states, with the most stable being Er-167m (t½ 2.269 seconds).
Additional recommended knowledge
The isotopes of erbium range in atomic weight from 142.9663 u (Er-143) to 176.9541 u (Er-177). The primary decay mode before the most abundant stable isotope, Er-166, is electron capture, and the primary mode after is beta decay. The primary decay products before Er-166 are element 67 (holmium) isotopes, and the primary products after are element 69 (thulium) isotopes.
Standard atomic mass: 167.259(3) 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
|
143Er
| 68
| 75
| 142.96634(64)#
| 200# ms
| 9/2-#
|
|
|
144Er
| 68
| 76
| 143.96038(43)#
| 400# ms [>200 ns]
| 0+
|
|
|
145Er
| 68
| 77
| 144.95739(43)#
| 900(300) ms
| 1/2+#
|
|
|
146Er
| 68
| 78
| 145.95200(32)#
| 1.7(6) s
| 0+
|
|
|
147Er
| 68
| 79
| 146.94949(32)#
| ~2.5 s
| (1/2+)
|
|
|
147mEr
| 100(50)# keV
| 2.5(2) s
| (11/2-)
|
|
|
148Er
| 68
| 80
| 147.94455(21)#
| 4.6(2) s
| 0+
|
|
|
149Er
| 68
| 81
| 148.94231(3)
| 4(2) s
| (1/2+)
|
|
|
149m1Er
| 741.8(2) keV
| 8.9(2) s
| (11/2-)
|
|
|
149m2Er
| 2611.1(3) keV
| 0.61(8) µs
| (19/2+)
|
|
|
149m3Er
| 3242.7+X keV
| 4.8(1) µs
| (27/2-)
|
|
|
150Er
| 68
| 82
| 149.937914(18)
| 18.5(7) s
| 0+
|
|
|
151Er
| 68
| 83
| 150.937449(18)
| 23.5(13) s
| (7/2-)
|
|
|
151m1Er
| 2585.5(6) keV
| 580(20) ms
| (27/2-)
|
|
|
151m2Er
| 10286+X keV
| 0.42(5) µs
| (67/2,69/2,71/2)
|
|
|
152Er
| 68
| 84
| 151.935050(11)
| 10.3(1) s
| 0+
|
|
|
153Er
| 68
| 85
| 152.935063(9)
| 37.1(2) s
| 7/2(-)
|
|
|
154Er
| 68
| 86
| 153.932783(6)
| 3.73(9) min
| 0+
|
|
|
155Er
| 68
| 87
| 154.933209(7)
| 5.3(3) min
| 7/2-
|
|
|
156Er
| 68
| 88
| 155.931065(26)
| 19.5(10) min
| 0+
|
|
|
157Er
| 68
| 89
| 156.93192(3)
| 18.65(10) min
| 3/2-
|
|
|
157mEr
| 155.4(3) keV
| 76(6) ms
| (9/2+)
|
|
|
158Er
| 68
| 90
| 157.929893(27)
| 2.29(6) h
| 0+
|
|
|
159Er
| 68
| 91
| 158.930684(5)
| 36(1) min
| 3/2-
|
|
|
159m1Er
| 182.602(24) keV
| 337(14) ns
| 9/2+
|
|
|
159m2Er
| 429.05(3) keV
| 590(60) ns
| 11/2-
|
|
|
160Er
| 68
| 92
| 159.929083(26)
| 28.58(9) h
| 0+
|
|
|
161Er
| 68
| 93
| 160.929995(10)
| 3.21(3) h
| 3/2-
|
|
|
161mEr
| 396.44(4) keV
| 7.5(7) µs
| 11/2-
|
|
|
162Er
| 68
| 94
| 161.928778(4)
| STABLE [>140E+12 a]
| 0+
| 0.00139(5)
|
|
163Er
| 68
| 95
| 162.930033(6)
| 75.0(4) min
| 5/2-
|
|
|
163mEr
| 445.5(6) keV
| 580(100) ns
| (11/2-)
|
|
|
164Er
| 68
| 96
| 163.929200(3)
| STABLE
| 0+
| 0.01601(3)
|
|
165Er
| 68
| 97
| 164.930726(3)
| 10.36(4) h
| 5/2-
|
|
|
166Er
| 68
| 98
| 165.9302931(27)
| STABLE
| 0+
| 0.33503(36)
|
|
167Er
| 68
| 99
| 166.9320482(27)
| STABLE
| 7/2+
| 0.22869(9)
|
|
167mEr
| 207.801(5) keV
| 2.269(6) s
| 1/2-
|
|
|
168Er
| 68
| 100
| 167.9323702(27)
| STABLE
| 0+
| 0.26978(18)
|
|
169Er
| 68
| 101
| 168.9345904(27)
| 9.392(18) d
| 1/2-
|
|
|
170Er
| 68
| 102
| 169.9354643(30)
| STABLE [>320E+15 a]
| 0+
| 0.14910(36)
|
|
171Er
| 68
| 103
| 170.9380298(30)
| 7.516(2) h
| 5/2-
|
|
|
171mEr
| 198.6(1) keV
| 210(10) ns
| 1/2-
|
|
|
172Er
| 68
| 104
| 171.939356(5)
| 49.3(3) h
| 0+
|
|
|
173Er
| 68
| 105
| 172.94240(21)#
| 1.434(17) min
| (7/2-)
|
|
|
174Er
| 68
| 106
| 173.94423(32)#
| 3.2(2) min
| 0+
|
|
|
175Er
| 68
| 107
| 174.94777(43)#
| 1.2(3) min
| (9/2+)
|
|
|
176Er
| 68
| 108
| 175.95008(43)#
| 20# s
| 0+
|
|
|
177Er
| 68
| 109
| 176.95405(54)#
| 3# s
| 1/2-#
|
|
|
Notes
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.
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