Erbium-156

Properties and data of the isotope ¹⁵⁶Er.

Content

General data

Name of the isotope:Erbium-156; Er-156Symbol:¹⁵⁶Er or 15668ErMass number A:156 (= number of nucleons)Atomic number Z:68 (= number of protons)Neutrons N:88Isotopic mass:155.931066(26) u (atomic weight of Erbium-156)Nuclide mass:155.8937659 u (calculated nuclear mass without electrons)Mass excess:-64.21161 MeVMass defect:1.363548784 u (per nucleus)Nuclear binding energy:1270.137511 MeV (per nucleus)
8.14190712 MeV (average binding energy per nucleon)Separation energy:S_N = 10.074(25) MeV (first neutron)
S_P = 5.46(3) MeV (first proton)Half-life:19.5(10) minDecay constant λ:0.00059243348765807 s^-1Specific activity α:2.301753492142 × 10⁺¹⁸ Bq g^-1
62209553.841684 Ci g^-1Spin and parity:
(nuclear angular momentum)0+Charge radius:5.1429(285) femtometer fmYear of discovery:1967

Radioactive Decay

Half-life T_½ = 19.5(10) min (minutes) respectively 1.170 × 10³ seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
EE/β⁺	¹⁵⁶Ho	ca. 100 %	1.27(6) MeV
α	¹⁵²Dy	trace	3.481(25) MeV

Parent Nuclides

Direct parent isotope is: ¹⁵⁶Tm.

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 88) and isobaric (same nucleon number A = 156) with Erbium-156. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

OZ	Isotone N = 88	Isobar A = 156
49	¹³⁷In
50	¹³⁸Sn
51	¹³⁹Sb
52	¹⁴⁰Te
53	¹⁴¹I
54	¹⁴²Xe
55	¹⁴³Cs
56	¹⁴⁴Ba
57	¹⁴⁵La	¹⁵⁶La
58	¹⁴⁶Ce	¹⁵⁶Ce
59	¹⁴⁷Pr	¹⁵⁶Pr
60	¹⁴⁸Nd	¹⁵⁶Nd
61	¹⁴⁹Pm	¹⁵⁶Pm
62	¹⁵⁰Sm	¹⁵⁶Sm
63	¹⁵¹Eu	¹⁵⁶Eu
64	¹⁵²Gd	¹⁵⁶Gd
65	¹⁵³Tb	¹⁵⁶Tb
66	¹⁵⁴Dy	¹⁵⁶Dy
67	¹⁵⁵Ho	¹⁵⁶Ho
68	¹⁵⁶Er	¹⁵⁶Er
69	¹⁵⁷Tm	¹⁵⁶Tm
70	¹⁵⁸Yb	¹⁵⁶Yb
71	¹⁵⁹Lu	¹⁵⁶Lu
72	¹⁶⁰Hf	¹⁵⁶Hf
73	¹⁶¹Ta	¹⁵⁶Ta
74	¹⁶²W
75	¹⁶³Re
76	¹⁶⁴Os
77	¹⁶⁵Ir
78	¹⁶⁶Pt