Thulium-172

Properties and data of the isotope ¹⁷²Tm.

Contents

General data

Name of the isotope:Thulium-172; Tm-172Symbol:¹⁷²Tm or 17269TmMass number A:172 (= number of nucleons)Atomic number Z:69 (= number of protons)Neutrons N:103Isotopic mass:171.938406(6) u (atomic weight of Thulium-172)Nuclide mass:171.9005574 u (calculated nuclear mass without electrons)Mass excess:-57.37444 MeVMass defect:1.494007556 u (per nucleus)Nuclear binding energy:1391.65907437 MeV (per nucleus)
8.09104113 MeV (average binding energy per nucleon)Separation energy:S_N = 6.235(5) MeV (first neutron)
S_P = 6.944(5) MeV (first proton)Half-life:63.6(2) hDecay constant λ:3.027372381900 × 10^-6 s^-1Specific activity α:1.066155726274 × 10⁺¹⁶ Bq g^-1
288150.1962903 Ci g^-1Spin and parity:
(nuclear angular momentum)2-Charge radius:5.2411(52) femtometer fmYear of discovery:1956

Radioactive Decay

Half-life T_½ = 63.6(2) h (hours) respectively 2.28960 × 10⁵ seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
β^-	¹⁷²Yb	100 %	1.881(6) MeV

Parent Nuclides

Direct parent isotope is: ¹⁷²Er.

Nuclear Isomers

Nuclear isomers or excited states with the activation energy in keV related to the ground state.

Nuclear Isomer	Excitation Energy	Half-life	Spin
^172mTm	476.2(2) keV	132(7) μs	(6+)

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 103) and isobaric (same nucleon number A = 172) with Thulium-172. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

Z	Isotone N = 103	Isobar A = 172
60	¹⁶³Nd
62	¹⁶⁵Sm
63	¹⁶⁶Eu
64	¹⁶⁷Gd
65	¹⁶⁸Tb	¹⁷²Tb
66	¹⁶⁹Dy	¹⁷²Dy
67	¹⁷⁰Ho	¹⁷²Ho
68	¹⁷¹Er	¹⁷²Er
69	¹⁷²Tm	¹⁷²Tm
70	¹⁷³Yb	¹⁷²Yb
71	¹⁷⁴Lu	¹⁷²Lu
72	¹⁷⁵Hf	¹⁷²Hf
73	¹⁷⁶Ta	¹⁷²Ta
74	¹⁷⁷W	¹⁷²W
75	¹⁷⁸Re	¹⁷²Re
76	¹⁷⁹Os	¹⁷²Os
77	¹⁸⁰Ir	¹⁷²Ir
78	¹⁸¹Pt	¹⁷²Pt
79	¹⁸²Au	¹⁷²Au
80	¹⁸³Hg	¹⁷²Hg
81	¹⁸⁴Tl
82	¹⁸⁵Pb
83	¹⁸⁶Bi
84	¹⁸⁷Po