Iridium-181

Properties and data of the isotope ¹⁸¹Ir.

Contents

General Data

Radioactive Decay

Parent Nuclides

Isotones und Isobares

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

General data

Name of the isotope:Iridium-181; Ir-181Symbol:¹⁸¹Ir or 18177IrMass number A:181 (= number of nucleons)Atomic number Z:77 (= number of protons)Neutrons N:104Nucleon pairing (Z - N):odd - evenNuclear ratio (N/Z ratio):1.3506493506494 (= neutron-proton ratio)Neutron excess (N-Z):27Isotopic mass:180.957635(6) u (atomic weight of Iridium-181)Nuclide mass:180.9153988 u (calculated nuclear mass without electrons)Mass excess:-39.46274 MeVMass defect:1.546043728 u (per nucleus)Nuclear binding energy:1440.13045637 MeV (per nucleus)
7.95652186 MeV (average binding energy per nucleon)Separation energy:S_N = 9.557(22) MeV (first neutron)
S_P = 2.394(17) MeV (first proton)Half-life:4.90(15) minDecay constant λ:0.0023576434712923 s^-1Specific activity α:7.887811712018 × 10⁺¹⁸ Bq g^-1
213184100.32481 Ci g^-1Spin and parity:
(nuclear angular momentum)5/2-Year of discovery:1972

Radioactive Decay

Half-life T_½ = 4.90(15) min (minutes) respectively 2.94 × 10² seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
EC/β⁺	¹⁸¹Os	100 %	4.087(26) MeV

Parent Nuclides

Direct parent isotopes are: ¹⁸⁵Au, ¹⁸¹Pt.

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 104) and isobaric (same nucleon number A = 181) with Iridium-181. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

Z	Isotone N = 104	Isobar A = 181
62	¹⁶⁶Sm
63	¹⁶⁷Eu
64	¹⁶⁸Gd
65	¹⁶⁹Tb
66	¹⁷⁰Dy
67	¹⁷¹Ho
68	¹⁷²Er
69	¹⁷³Tm
70	¹⁷⁴Yb	¹⁸¹Yb
71	¹⁷⁵Lu	¹⁸¹Lu
72	¹⁷⁶Hf	¹⁸¹Hf
73	¹⁷⁷Ta	¹⁸¹Ta
74	¹⁷⁸W	¹⁸¹W
75	¹⁷⁹Re	¹⁸¹Re
76	¹⁸⁰Os	¹⁸¹Os
77	¹⁸¹Ir	¹⁸¹Ir
78	¹⁸²Pt	¹⁸¹Pt
79	¹⁸³Au	¹⁸¹Au
80	¹⁸⁴Hg	¹⁸¹Hg
81	¹⁸⁵Tl	¹⁸¹Tl
82	¹⁸⁶Pb	¹⁸¹Pb
83	¹⁸⁷Bi
84	¹⁸⁸Po
85	¹⁸⁹At