Lead-201m1

Properties and data of the isotope ^201m1Pb.

Contents

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

General data

Name of the isotope:Lead-201m1; Pb-201m1Symbol:^201m1Pb or 201m182PbMass number A:201 (= number of nucleons)Atomic number Z:82 (= number of protons)Neutrons N:119Nucleon pairing (Z - N):even - oddNuclear ratio (N/Z ratio):1.4512195121951 (= neutron-proton ratio)Neutron excess (N-Z):37Excitation energy:629.1(3) keVIsotopic mass:200.97287(15) u (atomic weight of Lead-201m1)Nuclide mass:200.9278916 u (calculated nuclear mass without electrons)Mass excess:-25.27143 MeVMass defect:1.699907628 u (per nucleus)Nuclear binding energy:1583.45375604 MeV (per nucleus)
7.87787938 MeV (average binding energy per nucleon)Half-life:60.8(18) sDecay constant λ:0.011400447048683 s^-1Specific activity α:3.432754899671 × 10⁺¹⁹ Bq g^-1
927771594.5057 Ci g^-1Spin and parity:
(nuclear angular momentum)13/2+

Radioactive Decay

Half-life T_½ = 60.8(18) s respectively 6.08 × 10¹ seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
Iso	²⁰¹Pb	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
²⁰¹Pb		9.33(3) h	5/2-
^201m2Pb	2953(20) keV	508(5) ns	(29/2-)

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 119) and isobaric (same nucleon number A = 201) with Lead-201m1. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

Z	Isotone N = 119	Isobar A = 201
73	¹⁹²Ta
74	¹⁹³W
75	¹⁹⁴Re
76	¹⁹⁵Os	²⁰¹Os
77	¹⁹⁶Ir	²⁰¹Ir
78	¹⁹⁷Pt	²⁰¹Pt
79	¹⁹⁸Au	²⁰¹Au
80	¹⁹⁹Hg	²⁰¹Hg
81	²⁰⁰Tl	²⁰¹Tl
82	²⁰¹Pb	²⁰¹Pb
83	²⁰²Bi	²⁰¹Bi
84	²⁰³Po	²⁰¹Po
85	²⁰⁴At	²⁰¹At
86	²⁰⁵Rn	²⁰¹Rn
87	²⁰⁶Fr	²⁰¹Fr
88	²⁰⁷Ra	²⁰¹Ra
89	²⁰⁸Ac
90	²⁰⁹Th
91	²¹⁰Pa