Lead-205m1

Properties and data of the isotope ^205m1Pb.

Contents

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

General data

Name of the isotope:Lead-205m1; Pb-205m1Symbol:^205m1Pb or 205m182PbMass number A:205 (= number of nucleons)Atomic number Z:82 (= number of protons)Neutrons N:123Nucleon pairing (Z - N):even - oddNuclear ratio (N/Z ratio):1.5 (= neutron-proton ratio)Neutron excess (N-Z):41Excitation energy:2.329(7) keVIsotopic mass:204.9744817(12) u (atomic weight of Lead-205m1)Nuclide mass:204.9295033 u (calculated nuclear mass without electrons)Mass excess:-23.77014 MeVMass defect:1.732955592 u (per nucleus)Nuclear binding energy:1614.23773621 MeV (per nucleus)
7.87433042 MeV (average binding energy per nucleon)Half-life:24.2(4) μsDecay constant λ:28642.445477684 s^-1Specific activity α:8.455335354885 × 10⁺²⁵ Bq g^-1
2.285225771590 × 10⁺¹⁵ Ci g^-1Spin and parity:
(nuclear angular momentum)1/2-Year of discovery:1994

Radioactive Decay

Half-life T_½ = 24.2(4) μs respectively 2.42 × 10^-5 seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
Iso	²⁰⁵Pb	100 %

Nuclear Isomers

Nuclear isomers or excited states with the activation energy in keV related to the ground state.

Nuclear Isomer	Excitation Energy	Half-life	Spin
^205m2Pb	1013.85(3) keV	5.55(2) ms	13/2+
²⁰⁵Pb		1.70(9) × 10⁷a	5/2-
^205m3Pb	3195.7(5) keV	217(5) ns	25/2-

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 123) and isobaric (same nucleon number A = 205) with Lead-205m1. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

Z	Isotone N = 123	Isobar A = 205
74	¹⁹⁷W
75	¹⁹⁸Re
76	¹⁹⁹Os
77	²⁰⁰Ir	²⁰⁵Ir
78	²⁰¹Pt	²⁰⁵Pt
79	²⁰²Au	²⁰⁵Au
80	²⁰³Hg	²⁰⁵Hg
81	²⁰⁴Tl	²⁰⁵Tl
82	²⁰⁵Pb	²⁰⁵Pb
83	²⁰⁶Bi	²⁰⁵Bi
84	²⁰⁷Po	²⁰⁵Po
85	²⁰⁸At	²⁰⁵At
86	²⁰⁹Rn	²⁰⁵Rn
87	²¹⁰Fr	²⁰⁵Fr
88	²¹¹Ra	²⁰⁵Ra
89	²¹²Ac	²⁰⁵Ac
90	²¹³Th
91	²¹⁴Pa
92	²¹⁵U