Iridium-199

Properties and data of the isotope ¹⁹⁹Ir.

Contents

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

General data

Name of the isotope:Iridium-199; Ir-199Symbol:¹⁹⁹Ir or 19977IrMass number A:199 (= number of nucleons)Atomic number Z:77 (= number of protons)Neutrons N:122Nucleon pairing (Z - N):odd - evenNuclear ratio (N/Z ratio):1.5844155844156 (= neutron-proton ratio)Neutron excess (N-Z):45Isotopic mass:198.97381(4) u (atomic weight of Iridium-199)Nuclide mass:198.9315738 u (calculated nuclear mass without electrons)Mass excess:-24.39583 MeVMass defect:1.685837216 u (per nucleus)Nuclear binding energy:1570.34725168 MeV (per nucleus)
7.89119222 MeV (average binding energy per nucleon)Separation energy:S_N = 6.65(20) MeV (first neutron)
S_P = 7.85(20) MeV (first proton)Half-life:6 sDecay constant λ:0.11552453009332 s^-1Specific activity α:3.513661580808 × 10⁺²⁰ Bq g^-1
9496382650.8327 Ci g^-1Spin and parity:
(nuclear angular momentum)Year of discovery:1993

Radioactive Decay

Half-life T_½ = 6 s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
β^- ?	¹⁹⁹Pt	?	2.99(4) MeV

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 122) and isobaric (same nucleon number A = 199) with Iridium-199. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

Z	Isotone N = 122	Isobar A = 199
74	¹⁹⁶W
75	¹⁹⁷Re	¹⁹⁹Re
76	¹⁹⁸Os	¹⁹⁹Os
77	¹⁹⁹Ir	¹⁹⁹Ir
78	²⁰⁰Pt	¹⁹⁹Pt
79	²⁰¹Au	¹⁹⁹Au
80	²⁰²Hg	¹⁹⁹Hg
81	²⁰³Tl	¹⁹⁹Tl
82	²⁰⁴Pb	¹⁹⁹Pb
83	²⁰⁵Bi	¹⁹⁹Bi
84	²⁰⁶Po	¹⁹⁹Po
85	²⁰⁷At	¹⁹⁹At
86	²⁰⁸Rn	¹⁹⁹Rn
87	²⁰⁹Fr	¹⁹⁹Fr
88	²¹⁰Ra
89	²¹¹Ac
90	²¹²Th
91	²¹³Pa
92	²¹⁴U