Bismuth-205

Properties and data of the isotope ²⁰⁵Bi.

Contents

General data

Name of the isotope:Bismuth-205; Bi-205Symbol:²⁰⁵Bi or 20583BiMass number A:205 (= number of nucleons)Atomic number Z:83 (= number of protons)Neutrons N:122Isotopic mass:204.977385(5) u (atomic weight of Bismuth-205)Nuclide mass:204.9318581 u (calculated nuclear mass without electrons)Mass excess:-21.06574 MeVMass defect:1.729212408 u (per nucleus)Nuclear binding energy:1610.75098278 MeV (per nucleus)
7.85732187 MeV (average binding energy per nucleon)Separation energy:S_N = 8.491(10) MeV (first neutron)
S_P = 3.245(5) MeV (first proton)Half-life:14.91(7) dDecay constant λ:5.380641725041 × 10^-7 s^-1Specific activity α:1.588381489463 × 10⁺¹⁵ Bq g^-1
42929.229444954 Ci g^-1Spin and parity:
(nuclear angular momentum)9/2-Charge radius:5.5008(909) femtometer fmYear of discovery:1951

Radioactive Decay

Half-life T_½ = 14.91(7) d respectively 1.288224 × 10⁶ seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
EC/β⁺	²⁰⁵Pb	100 %	2.705(5) MeV

Parent Nuclides

Direct parent isotopes are: ²⁰⁹At, ²⁰⁵Po.

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 122) and isobaric (same nucleon number A = 205) with Bismuth-205. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

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