Thulium-157

Properties and data of the isotope ¹⁵⁷Tm.

Content

General data

Name of the isotope:Thulium-157; Tm-157Symbol:¹⁵⁷Tm or 15769TmMass number A:157 (= number of nucleons)Atomic number Z:69 (= number of protons)Neutrons N:88Isotopic mass:156.93697(3) u (atomic weight of Thulium-157)Nuclide mass:156.8991214 u (calculated nuclear mass without electrons)Mass excess:-58.71207 MeVMass defect:1.365469816 u (per nucleus)Nuclear binding energy:1271.92694079 MeV (per nucleus)
8.10144548 MeV (average binding energy per nucleon)Separation energy:S_N = 9.95(3) MeV (first neutron)
S_P = 1.79(4) MeV (first proton)Half-life:3.63(9) minDecay constant λ:0.0031824939419649 s^-1Specific activity α:1.228553000282 × 10⁺¹⁹ Bq g^-1
332041351.4277 Ci g^-1Spin and parity:
(nuclear angular momentum)1/2+Magnetic dipole moment:μ(μ_N) = + 0.476(15)Nuclear g-factor:g_l = 0.952Charge radius:5.1140(74) femtometer fmYear of discovery:1974

Radioactive Decay

Half-life T_½ = 3.63(9) min (minutes) respectively 2.178 × 10² seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
EE/β⁺	¹⁵⁷Er	100 %	4.7943 MeV

Parent Nuclides

Direct parent isotope is: ¹⁵⁷Yb.

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 88) and isobaric (same nucleon number A = 157) with Thulium-157. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

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