Bismuth-185

Properties and data of the isotope ¹⁸⁵Bi.

Contents

General data

Name of the isotope:Bismuth-185; Bi-185Symbol:¹⁸⁵Bi or 18583BiMass number A:185 (= number of nucleons)Atomic number Z:83 (= number of protons)Neutrons N:102Isotopic mass:184.99760(9) u (atomic weight of Bismuth-185)Nuclide mass:184.9520731 u (calculated nuclear mass without electrons)Mass excess:-2.23559 MeVMass defect:1.535699088 u (per nucleus)Nuclear binding energy:1430.49448628 MeV (per nucleus)
7.73240263 MeV (average binding energy per nucleon)Separation energy:S_N = 11.37(8) MeV (first neutron)
S_P = -1.53(8) MeV (first proton)Half-life:58(4) μsDecay constant λ:11950.81345793 s^-1Specific activity α:3.911384893178 × 10⁺²⁵ Bq g^-1
1.057131052210 × 10⁺¹⁵ Ci g^-1Spin and parity:
(nuclear angular momentum)1/2+Year of discovery:1996

Radioactive Decay

Half-life T_½ = 58(4) μs respectively 5.8 × 10^-5 seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
α	¹⁸¹Tl	10(2) %	8.14(8) MeV
p	¹⁸⁴Pb	90(2) %

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 102) and isobaric (same nucleon number A = 185) with Bismuth-185. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

Z	Isotone N = 102	Isobar A = 185
60	¹⁶²Nd
61	¹⁶³Pm
62	¹⁶⁴Sm
63	¹⁶⁵Eu
64	¹⁶⁶Gd
65	¹⁶⁷Tb
66	¹⁶⁸Dy
67	¹⁶⁹Ho
68	¹⁷⁰Er
69	¹⁷¹Tm
70	¹⁷²Yb	¹⁸⁵Yb
71	¹⁷³Lu	¹⁸⁵Lu
72	¹⁷⁴Hf	¹⁸⁵Hf
73	¹⁷⁵Ta	¹⁸⁵Ta
74	¹⁷⁶W	¹⁸⁵W
75	¹⁷⁷Re	¹⁸⁵Re
76	¹⁷⁸Os	¹⁸⁵Os
77	¹⁷⁹Ir	¹⁸⁵Ir
78	¹⁸⁰Pt	¹⁸⁵Pt
79	¹⁸¹Au	¹⁸⁵Au
80	¹⁸²Hg	¹⁸⁵Hg
81	¹⁸³Tl	¹⁸⁵Tl
82	¹⁸⁴Pb	¹⁸⁵Pb
83	¹⁸⁵Bi	¹⁸⁵Bi
84	¹⁸⁶Po