Iridium-198

Properties and data of the isotope ¹⁹⁸Ir.

Contents

General data

Name of the isotope:Iridium-198; Ir-198Symbol:¹⁹⁸Ir or 19877IrMass number A:198 (= number of nucleons)Atomic number Z:77 (= number of protons)Neutrons N:121Isotopic mass:197.97228(21) u (atomic weight of Iridium-198)Nuclide mass:197.9300438 u (calculated nuclear mass without electrons)Mass excess:-25.82101 MeVMass defect:1.6787023 u (per nucleus)Nuclear binding energy:1563.70112024 MeV (per nucleus)
7.89748041 MeV (average binding energy per nucleon)Separation energy:S_N = 5.63(20) MeV (first neutron)
S_P = 7.80(28) MeV (first proton)Half-life:8(1) sDecay constant λ:0.086643397569993 s^-1Specific activity α:2.64862306979 × 10⁺²⁰ Bq g^-1
7158440729.1811 Ci g^-1Spin and parity:
(nuclear angular momentum)Year of discovery:1973

Radioactive Decay

Half-life T_½ = 8(1) s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
β^-	¹⁹⁸Pt	100 %	4.08(20) MeV

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 121) and isobaric (same nucleon number A = 198) with Iridium-198. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

Z	Isotone N = 121	Isobar A = 198
73	¹⁹⁴Ta
74	¹⁹⁵W
75	¹⁹⁶Re	¹⁹⁸Re
76	¹⁹⁷Os	¹⁹⁸Os
77	¹⁹⁸Ir	¹⁹⁸Ir
78	¹⁹⁹Pt	¹⁹⁸Pt
79	²⁰⁰Au	¹⁹⁸Au
80	²⁰¹Hg	¹⁹⁸Hg
81	²⁰²Tl	¹⁹⁸Tl
82	²⁰³Pb	¹⁹⁸Pb
83	²⁰⁴Bi	¹⁹⁸Bi
84	²⁰⁵Po	¹⁹⁸Po
85	²⁰⁶At	¹⁹⁸At
86	²⁰⁷Rn	¹⁹⁸Rn
87	²⁰⁸Fr
88	²⁰⁹Ra
89	²¹⁰Ac
90	²¹¹Th
91	²¹²Pa