Lead-203

Properties and data of the isotope ²⁰³Pb.

Contents

General data

Name of the isotope:Lead-203; Pb-203Symbol:²⁰³Pb or 20382PbMass number A:203 (= number of nucleons)Atomic number Z:82 (= number of protons)Neutrons N:121Isotopic mass:202.973391(7) u (atomic weight of Lead-203)Nuclide mass:202.9284126 u (calculated nuclear mass without electrons)Mass excess:-24.78612 MeVMass defect:1.71671646 u (per nucleus)Nuclear binding energy:1599.11108219 MeV (per nucleus)
7.87739449 MeV (average binding energy per nucleon)Separation energy:S_N = 6.917(8) MeV (first neutron)
S_P = 6.095(7) MeV (first proton)Half-life:51.92(3) hDecay constant λ:3.708414551018 × 10^-6 s^-1Specific activity α:1.105573999666 × 10⁺¹⁶ Bq g^-1
298803.78369376 Ci g^-1Spin and parity:
(nuclear angular momentum)5/2-Magnetic dipole moment:μ(μ_N) = + 0.6864(5)Quadrupole moment Q:+ 0.95 barn (100 fm²)Nuclear g-factor:g_l = 0.27456Charge radius:5.4727(17) femtometer fmYear of discovery:1942

Radioactive Decay

Half-life T_½ = 51.92(3) h (hours) respectively 1.86912 × 10⁵ seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
EE	²⁰³Tl	100 %	0.975(7) MeV

Parent Nuclides

Direct parent isotopes are: ²⁰³Bi, ²⁰⁷Po.

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
^203m1Pb	825.2(3) keV	6.21(11) s	13/2+
^203m3Pb	2949.2(4) keV	480(7) ms	29/2-
^203m2Pb	2923.4+x keV	122(4) ns	(25/2-)

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 121) and isobaric (same nucleon number A = 203) with Lead-203. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

Z	Isotone N = 121	Isobar A = 203
73	¹⁹⁴Ta
74	¹⁹⁵W
75	¹⁹⁶Re
76	¹⁹⁷Os	²⁰³Os
77	¹⁹⁸Ir	²⁰³Ir
78	¹⁹⁹Pt	²⁰³Pt
79	²⁰⁰Au	²⁰³Au
80	²⁰¹Hg	²⁰³Hg
81	²⁰²Tl	²⁰³Tl
82	²⁰³Pb	²⁰³Pb
83	²⁰⁴Bi	²⁰³Bi
84	²⁰⁵Po	²⁰³Po
85	²⁰⁶At	²⁰³At
86	²⁰⁷Rn	²⁰³Rn
87	²⁰⁸Fr	²⁰³Fr
88	²⁰⁹Ra	²⁰³Ra
89	²¹⁰Ac	²⁰³Ac
90	²¹¹Th
91	²¹²Pa