Iridium-205

Properties and data of the isotope ²⁰⁵Ir.

Contents

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

General data

Name of the isotope:Iridium-205; Ir-205Symbol:²⁰⁵Ir or 20577IrMass number A:205 (= number of nucleons)Atomic number Z:77 (= number of protons)Neutrons N:128Nucleon pairing (Z - N):odd - evenNuclear ratio (N/Z ratio):1.6623376623377 (= neutron-proton ratio)Neutron excess (N-Z):51Isotopic mass:204.99360(54) u (atomic weight of Iridium-205)Nuclide mass:204.9513638 u (calculated nuclear mass without electrons)Mass excess:-5.96156 MeVMass defect:1.718036712 u (per nucleus)Nuclear binding energy:1600.34088901 MeV (per nucleus)
7.80654092 MeV (average binding energy per nucleon)Separation energy:S_N = 4.34(64) MeV (first neutron)Half-life:160 nsDecay constant λ:4332169.8784997 s^-1Specific activity α:1.278869472426 × 10⁺²⁸ Bq g^-1
3.456403979531 × 10⁺¹⁷ Ci g^-1Spin and parity:
(nuclear angular momentum)Year of discovery:2012

Radioactive Decay

Half-life T_½ = 160 ns respectively 1.6 × 10^-7 seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
β^-	²⁰⁵Pt	?	7.01(58) MeV
β^-, n	²⁰⁴Pt	?	3.89(54) MeV

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 128) and isobaric (same nucleon number A = 205) with Iridium-205. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

Z	Isotone N = 128	Isobar A = 205
77	²⁰⁵Ir	²⁰⁵Ir
78	²⁰⁶Pt	²⁰⁵Pt
79	²⁰⁷Au	²⁰⁵Au
80	²⁰⁸Hg	²⁰⁵Hg
81	²⁰⁹Tl	²⁰⁵Tl
82	²¹⁰Pb	²⁰⁵Pb
83	²¹¹Bi	²⁰⁵Bi
84	²¹²Po	²⁰⁵Po
85	²¹³At	²⁰⁵At
86	²¹⁴Rn	²⁰⁵Rn
87	²¹⁵Fr	²⁰⁵Fr
88	²¹⁶Ra	²⁰⁵Ra
89	²¹⁷Ac	²⁰⁵Ac
90	²¹⁸Th
91	²¹⁹Pa
92	²²⁰U
93	²²¹Np
95	²²³Am