Isotopes of erbium

Naturally occurring erbium (Er) is composed of 6 stable isotopes, ¹⁶²Er, ¹⁶⁴Er, ¹⁶⁶Er, ¹⁶⁷Er, ¹⁶⁸Er, and ¹⁷⁰Er with ¹⁶⁶Er being the most abundant (33.503% natural abundance). Thirty radioisotopes have been characterized with between 74 and 108 neutrons, or 142 to 177 nucleons, with the most stable being ¹⁶⁹Er with a half-life of 9.4 days, ¹⁷²Er with a half-life of 49.3 hours, ¹⁶⁰Er with a half-life of 28.58 hours, ¹⁶⁵Er with a half-life of 10.36 hours, and ¹⁷¹Er with a half-life of 7.516 hours. All of the remaining radioactive isotopes have half-lives that are less than 3.5 hours, and the majority of these have half-lives that are less than 4 minutes. This element also has 13 meta states, with the most stable being ^167mEr (t_1/2 2.269 seconds).

The isotopes of erbium range in atomic weight from 141.9723 u (¹⁴²Er) to 176.9541 u (¹⁷⁷Er). The primary decay mode before the most abundant stable isotope, ¹⁶⁶Er, is electron capture, and the primary mode after is beta decay. The primary decay products before ¹⁶⁶Er are holmium isotopes, and the primary products after are thulium isotopes.

Relative atomic mass: 167.259(3).

Table

nuclide symbol	Z(p)	N(n)	isotopic mass (u)	half-life	decay mode(s)^[1]^{[n 1]}	daughter isotope(s)^{[n 2]}	nuclear spin	representative isotopic composition (mole fraction)	range of natural variation (mole fraction)
nuclide symbol	excitation energy			half-life	decay mode(s)^[1]^{[n 1]}	daughter isotope(s)^{[n 2]}	nuclear spin	representative isotopic composition (mole fraction)	range of natural variation (mole fraction)
¹⁴²Er	68	74	141.97231(47)#				0+
¹⁴³Er	68	75	142.96634(64)#	200# ms			9/2−#
¹⁴⁴Er	68	76	143.96038(43)#	400# ms [>200 ns]	β⁺	¹⁴⁴Ho	0+
¹⁴⁵Er	68	77	144.95739(43)#	900(300) ms	β⁺	¹⁴⁵Ho	1/2+#
¹⁴⁵Er	68	77	144.95739(43)#	900(300) ms	β⁺, p (rare)	¹⁴⁴Dy	1/2+#
¹⁴⁶Er	68	78	145.95200(32)#	1.7(6) s	β⁺	¹⁴⁶Ho	0+
¹⁴⁶Er	68	78	145.95200(32)#	1.7(6) s	β⁺, p	¹⁴⁵Dy	0+
¹⁴⁷Er	68	79	146.94949(32)#	~2.5 s	β⁺	¹⁴⁷Ho	(1/2+)
¹⁴⁷Er	68	79	146.94949(32)#	~2.5 s	β⁺, p	¹⁴⁶Dy	(1/2+)
^147mEr	100(50)# keV			2.5(2) s	β⁺	¹⁴⁷Ho	(11/2−)
¹⁴⁸Er	68	80	147.94455(21)#	4.6(2) s	β⁺ (99.85%)	¹⁴⁸Ho	0+
¹⁴⁸Er	68	80	147.94455(21)#	4.6(2) s	β⁺, p (.15%)	¹⁴⁷Dy	0+
¹⁴⁹Er	68	81	148.94231(3)	4(2) s	β⁺ (93%)	¹⁴⁹Ho	(1/2+)
¹⁴⁹Er	68	81	148.94231(3)	4(2) s	β⁺, p (7%)	¹⁴⁸Dy	(1/2+)
^149m1Er	741.8(2) keV			8.9(2) s	β⁺ (96.5%)	¹⁴⁹Ho	(11/2−)
					IT (3.5%)	¹⁴⁹Er
					β⁺, p (.18%)	¹⁴⁸Dy
^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	β⁺	¹⁵⁰Ho	0+
¹⁵¹Er	68	83	150.937449(18)	23.5(13) s	β⁺	¹⁵¹Ho	(7/2−)
^151m1Er	2585.5(6) keV			580(20) ms	IT (95.3%)	¹⁵¹Er	(27/2−)
^151m1Er	2585.5(6) keV			580(20) ms	β⁺ (4.7%)	¹⁵¹Ho	(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	α (90%)	¹⁴⁸Dy	0+
¹⁵²Er	68	84	151.935050(11)	10.3(1) s	β⁺ (10%)	¹⁵²Ho	0+
¹⁵³Er	68	85	152.935063(9)	37.1(2) s	α (53%)	¹⁴⁹Dy	7/2(−)
¹⁵³Er	68	85	152.935063(9)	37.1(2) s	β⁺ (47%)	¹⁵³Ho	7/2(−)
¹⁵⁴Er	68	86	153.932783(6)	3.73(9) min	β⁺ (99.53%)	¹⁵⁴Ho	0+
¹⁵⁴Er	68	86	153.932783(6)	3.73(9) min	α (.47%)	¹⁵⁰Dy	0+
¹⁵⁵Er	68	87	154.933209(7)	5.3(3) min	β⁺ (99.98%)	¹⁵⁵Ho	7/2−
¹⁵⁵Er	68	87	154.933209(7)	5.3(3) min	α (.022%)	¹⁵¹Dy	7/2−
¹⁵⁶Er	68	88	155.931065(26)	19.5(10) min	β⁺	¹⁵⁶Ho	0+
¹⁵⁷Er	68	89	156.93192(3)	18.65(10) min	β⁺	¹⁵⁷Ho	3/2−
^157mEr	155.4(3) keV			76(6) ms	IT	¹⁵⁷Er	(9/2+)
¹⁵⁸Er	68	90	157.929893(27)	2.29(6) h	EC	¹⁵⁸Ho	0+
¹⁵⁹Er	68	91	158.930684(5)	36(1) min	β⁺	¹⁵⁹Ho	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	EC	¹⁶⁰Ho	0+
¹⁶¹Er	68	93	160.929995(10)	3.21(3) h	β⁺	¹⁶¹Ho	3/2−
^161mEr	396.44(4) keV			7.5(7) µs			11/2−
¹⁶²Er	68	94	161.928778(4)	Observationally Stable^{[n 3]}			0+	0.00139(5)
¹⁶³Er	68	95	162.930033(6)	75.0(4) min	β⁺	¹⁶³Ho	5/2−
^163mEr	445.5(6) keV			580(100) ns			(11/2−)
¹⁶⁴Er	68	96	163.929200(3)	Observationally Stable^{[n 4]}			0+	0.01601(3)
¹⁶⁵Er	68	97	164.930726(3)	10.36(4) h	EC	¹⁶⁵Ho	5/2−
¹⁶⁶Er	68	98	165.9302931(27)	Observationally Stable^{[n 5]}			0+	0.33503(36)
¹⁶⁷Er	68	99	166.9320482(27)	Observationally Stable^{[n 6]}			7/2+	0.22869(9)
^167mEr	207.801(5) keV			2.269(6) s	IT	¹⁶⁷Er	1/2−
¹⁶⁸Er	68	100	167.9323702(27)	Observationally Stable^{[n 7]}			0+	0.26978(18)
¹⁶⁹Er	68	101	168.9345904(27)	9.392(18) d	β⁻	¹⁶⁹Tm	1/2−
¹⁷⁰Er	68	102	169.9354643(30)	Observationally Stable^{[n 8]}			0+	0.14910(36)
¹⁷¹Er	68	103	170.9380298(30)	7.516(2) h	β⁻	¹⁷¹Tm	5/2−
^171mEr	198.6(1) keV			210(10) ns			1/2−
¹⁷²Er	68	104	171.939356(5)	49.3(3) h	β⁻	¹⁷²Tm	0+
¹⁷³Er	68	105	172.94240(21)#	1.434(17) min	β⁻	¹⁷³Tm	(7/2−)
¹⁷⁴Er	68	106	173.94423(32)#	3.2(2) min	β⁻	¹⁷⁴Tm	0+
¹⁷⁵Er	68	107	174.94777(43)#	1.2(3) min	β⁻	¹⁷⁵Tm	(9/2+)
¹⁷⁶Er	68	108	175.95008(43)#	20# s	β⁻	¹⁷⁶Tm	0+
¹⁷⁷Er	68	109	176.95405(54)#	3# s	β⁻	¹⁷⁷Tm	1/2−#

↑ Abbreviations:
EC: Electron capture
IT: Isomeric transition
↑ Bold for stable isotopes
↑ Believed to undergo α decay to ¹⁵⁸Dy or β⁺β⁺ to ¹⁶²Dy with a half-life over 140×10¹² years
↑ Believed to undergo α decay to ¹⁶⁰Dy or β⁺β⁺ to ¹⁶⁴Dy
↑ Believed to undergo α decay to ¹⁶²Dy
↑ Believed to undergo α decay to ¹⁶³Dy
↑ Believed to undergo α decay to ¹⁶⁴Dy
↑ Believed to undergo α decay to ¹⁶⁶Dy or β⁻β⁻ to ¹⁷⁰Yb with a half-life over 320×10¹⁵ years

References

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Isotope masses from:
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Isotopic compositions and standard atomic masses from:
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Half-life, spin, and isomer data selected from the following sources. See editing notes on this article's talk page.
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Isotopes of holmium	Isotopes of erbium	Isotopes of thulium
Table of nuclides

[2] Abbreviations:
EC: Electron capture
IT: Isomeric transition

[3] Bold for stable isotopes

[4] Believed to undergo α decay to ¹⁵⁸Dy or β⁺β⁺ to ¹⁶²Dy with a half-life over 140×10¹² years

[5] Believed to undergo α decay to ¹⁶⁰Dy or β⁺β⁺ to ¹⁶⁴Dy

[6] Believed to undergo α decay to ¹⁶²Dy

[7] Believed to undergo α decay to ¹⁶³Dy

[8] Believed to undergo α decay to ¹⁶⁴Dy

[9] Believed to undergo α decay to ¹⁶⁶Dy or β⁻β⁻ to ¹⁷⁰Yb with a half-life over 320×10¹⁵ years

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v t e Isotopes of the chemical elements
1 H																	2 He
3 Li	4 Be											5 B	6 C	7 N	8 O	9 F	10 Ne
11 Na	12 Mg											13 Al	14 Si	15 P	16 S	17 Cl	18 Ar
19 K	20 Ca	21 Sc	22 Ti	23 V	24 Cr	25 Mn	26 Fe	27 Co	28 Ni	29 Cu	30 Zn	31 Ga	32 Ge	33 As	34 Se	35 Br	36 Kr
37 Rb	38 Sr	39 Y	40 Zr	41 Nb	42 Mo	43 Tc	44 Ru	45 Rh	46 Pd	47 Ag	48 Cd	49 In	50 Sn	51 Sb	52 Te	53 I	54 Xe
55 Cs	56 Ba		72 Hf	73 Ta	74 W	75 Re	76 Os	77 Ir	78 Pt	79 Au	80 Hg	81 Tl	82 Pb	83 Bi	84 Po	85 At	86 Rn
87 Fr	88 Ra		104 Rf	105 Db	106 Sg	107 Bh	108 Hs	109 Mt	110 Ds	111 Rg	112 Cn	113 Uut	114 Fl	115 Uup	116 Lv	117 Uus	118 Uuo

		57 La	58 Ce	59 Pr	60 Nd	61 Pm	62 Sm	63 Eu	64 Gd	65 Tb	66 Dy	67 Ho	68 Er	69 Tm	70 Yb	71 Lu
		89 Ac	90 Th	91 Pa	92 U	93 Np	94 Pu	95 Am	96 Cm	97 Bk	98 Cf	99 Es	100 Fm	101 Md	102 No	103 Lr
Table of nuclides Categories: Isotopes Tables of nuclides Metastable isotopes Isotopes by element

Isotopes of erbium

Table

References

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