Erbium-166

Properties and data of the isotope ¹⁶⁶Er.

Content

General data

Name of the isotope:Erbium-166; Er-166Symbol:¹⁶⁶Er or 16668ErMass number A:166 (= number of nucleons)Atomic number Z:68 (= number of protons)Neutrons N:98Isotopic mass:165.93030(2) u (atomic weight of Erbium-166)Nuclide mass:165.8929999 u (calculated nuclear mass without electrons)Mass excess:-64.92513 MeVMass defect:1.450963944 u (per nucleus)Nuclear binding energy:1351.56420805 MeV (per nucleus)
8.14195306 MeV (average binding energy per nucleon)Separation energy:S_N = 8.4757(13) MeV (first neutron)
S_P = 7.3160(9) MeV (first proton)Half-life:stableSpin and parity:
(nuclear angular momentum)0+Charge radius:5.2516(31) femtometer fmYear of discovery:1934

Parent Nuclides

Direct parent isotopes are: ¹⁶⁶Tm, ¹⁶⁶Ho.

Occurrence

Comparison of the natural Erbium isotopes including isotopic abundance (mole fraction of the isotope mixture in percent):

	Atomic Mass m_a	Quantity	Half-life	Spin
Erbium Isotopic mixture	167.259 u	100 %
Isotope ¹⁶²Er	161.92879(2) u	0.139(5) %	stable	0+
Isotope ¹⁶⁴Er	163.92921(2) u	1.601(3) %	stable	0+
Isotope ¹⁶⁶Er	165.93030(2) u	33.503(36) %	stable	0+
Isotope ¹⁶⁷Er	166.93205(2) u	22.869(9) %	stable	7/2+
Isotope ¹⁶⁸Er	167.93238(2) u	26.978(18) %	stable	0+
Isotope ¹⁷⁰Er	169.93547(2) u	14.910(36) %	stable	0+

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 98) and isobaric (same nucleon number A = 166) with Erbium-166. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

OZ	Isotone N = 98	Isobar A = 166
57	¹⁵⁵La
58	¹⁵⁶Ce
59	¹⁵⁷Pr
60	¹⁵⁸Nd
61	¹⁵⁹Pm
62	¹⁶⁰Sm	¹⁶⁶Sm
63	¹⁶¹Eu	¹⁶⁶Eu
64	¹⁶²Gd	¹⁶⁶Gd
65	¹⁶³Tb	¹⁶⁶Tb
66	¹⁶⁴Dy	¹⁶⁶Dy
67	¹⁶⁵Ho	¹⁶⁶Ho
68	¹⁶⁶Er	¹⁶⁶Er
69	¹⁶⁷Tm	¹⁶⁶Tm
70	¹⁶⁸Yb	¹⁶⁶Yb
71	¹⁶⁹Lu	¹⁶⁶Lu
72	¹⁷⁰Hf	¹⁶⁶Hf
73	¹⁷¹Ta	¹⁶⁶Ta
74	¹⁷²W	¹⁶⁶W
75	¹⁷³Re	¹⁶⁶Re
76	¹⁷⁴Os	¹⁶⁶Os
77	¹⁷⁵Ir	¹⁶⁶Ir
78	¹⁷⁶Pt	¹⁶⁶Pt
79	¹⁷⁷Au
80	¹⁷⁸Hg
81	¹⁷⁹Tl
82	¹⁸⁰Pb