Osmium-181

Properties and data of the isotope ¹⁸¹Os.

Contents

General Data

Radioactive Decay

Parent Nuclides

Isotones und Isobares

See also: List of individual Osmium isotopes (and general data sources).

General data

Name of the isotope:Osmium-181; Os-181Symbol:¹⁸¹Os or 18176OsMass number A:181 (= number of nucleons)Atomic number Z:76 (= number of protons)Neutrons N:105Isotopic mass:180.953247(27) u (atomic weight of Osmium-181)Nuclide mass:180.9115592 u (calculated nuclear mass without electrons)Mass excess:-43.55014 MeVMass defect:1.551271612 u (per nucleus)Nuclear binding energy:1445.00019895 MeV (per nucleus)
7.98342651 MeV (average binding energy per nucleon)Separation energy:S_N = 7.26(3) MeV (first neutron)
S_P = 5.00(3) MeV (first proton)Half-life:105(3) minDecay constant λ:0.00011002336199364 s^-1Specific activity α:3.680978798941 × 10⁺¹⁷ Bq g^-1
9948591.3484914 Ci g^-1Spin and parity:
(nuclear angular momentum)1/2-Year of discovery:1966

Radioactive Decay

Half-life T_½ = 105(3) min (minutes) respectively 6.300 × 10³ seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
EC/β⁺	¹⁸¹Re	100 %	2.967(28) MeV

Parent Nuclides

Direct parent isotopes are: ¹⁸⁵Pt, ¹⁸¹Ir.

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
^181mOs	49.20(14) keV	2.7(1) min	7/2-

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 105) and isobaric (same nucleon number A = 181) with Osmium-181. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

Z	Isotone N = 105	Isobar A = 181
63	¹⁶⁸Eu
64	¹⁶⁹Gd
65	¹⁷⁰Tb
66	¹⁷¹Dy
67	¹⁷²Ho
68	¹⁷³Er
69	¹⁷⁴Tm
70	¹⁷⁵Yb	¹⁸¹Yb
71	¹⁷⁶Lu	¹⁸¹Lu
72	¹⁷⁷Hf	¹⁸¹Hf
73	¹⁷⁸Ta	¹⁸¹Ta
74	¹⁷⁹W	¹⁸¹W
75	¹⁸⁰Re	¹⁸¹Re
76	¹⁸¹Os	¹⁸¹Os
77	¹⁸²Ir	¹⁸¹Ir
78	¹⁸³Pt	¹⁸¹Pt
79	¹⁸⁴Au	¹⁸¹Au
80	¹⁸⁵Hg	¹⁸¹Hg
81	¹⁸⁶Tl	¹⁸¹Tl
82	¹⁸⁷Pb	¹⁸¹Pb
83	¹⁸⁸Bi
84	¹⁸⁹Po
85	¹⁹⁰At