Erbium-172

Properties and data of the isotope ¹⁷²Er.

Content

General data

Name of the isotope:Erbium-172; Er-172Symbol:¹⁷²Er or 17268ErMass number A:172 (= number of nucleons)Atomic number Z:68 (= number of protons)Neutrons N:104Isotopic mass:171.939362(4) u (atomic weight of Erbium-172)Nuclide mass:171.9020619 u (calculated nuclear mass without electrons)Mass excess:-56.48393 MeVMass defect:1.49389144 u (per nucleus)Nuclear binding energy:1391.55091301 MeV (per nucleus)
8.09041228 MeV (average binding energy per nucleon)Separation energy:S_N = 6.836(4) MeV (first neutron)
S_P = 9.25(60) MeV (first proton)Half-life:49.3(3) hDecay constant λ:3.905494594094 × 10^-6 s^-1Specific activity α:1.37540576452 × 10⁺¹⁶ Bq g^-1
371731.28770919 Ci g^-1Spin and parity:
(nuclear angular momentum)0+Year of discovery:1956

Radioactive Decay

Half-life T_½ = 49.3(3) h (hours) respectively 1.77480 × 10⁵ seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
β^-	¹⁷²Tm	100 %	0.891(5) MeV

Parent Nuclides

Direct parent isotope is: ¹⁷²Ho.

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 104) and isobaric (same nucleon number A = 172) with Erbium-172. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

OZ	Isotone N = 104	Isobar A = 172
62	¹⁶⁶Sm
63	¹⁶⁷Eu
64	¹⁶⁸Gd
65	¹⁶⁹Tb	¹⁷²Tb
66	¹⁷⁰Dy	¹⁷²Dy
67	¹⁷¹Ho	¹⁷²Ho
68	¹⁷²Er	¹⁷²Er
69	¹⁷³Tm	¹⁷²Tm
70	¹⁷⁴Yb	¹⁷²Yb
71	¹⁷⁵Lu	¹⁷²Lu
72	¹⁷⁶Hf	¹⁷²Hf
73	¹⁷⁷Ta	¹⁷²Ta
74	¹⁷⁸W	¹⁷²W
75	¹⁷⁹Re	¹⁷²Re
76	¹⁸⁰Os	¹⁷²Os
77	¹⁸¹Ir	¹⁷²Ir
78	¹⁸²Pt	¹⁷²Pt
79	¹⁸³Au	¹⁷²Au
80	¹⁸⁴Hg	¹⁷²Hg
81	¹⁸⁵Tl
82	¹⁸⁶Pb
83	¹⁸⁷Bi
84	¹⁸⁸Po