Lead-212

Properties and data of the isotope ²¹²Pb.

Contents

General Data

Radioactive Decay

Parent Nuclides

Isotones und Isobares

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

General data

Name of the isotope:Lead-212; Pb-212Other names:Thorium BSymbol:²¹²Pb or 21282PbMass number A:212 (= number of nucleons)Atomic number Z:82 (= number of protons)Neutrons N:130Isotopic mass:211.991896(2) u (atomic weight of Lead-212)Nuclide mass:211.9469176 u (calculated nuclear mass without electrons)Mass excess:-7.54883 MeVMass defect:1.776195704 u (per nucleus)Nuclear binding energy:1654.5156411 MeV (per nucleus)
7.80431906 MeV (average binding energy per nucleon)Separation energy:S_N = 5.1272(25) MeV (first neutron)
S_P = 8.76(4) MeV (first proton)Half-life:10.64(1) hDecay constant λ:1.809594769632 × 10^-5 s^-1Specific activity α:5.164755735606 × 10⁺¹⁶ Bq g^-1
1395879.9285424 Ci g^-1Spin and parity:
(nuclear angular momentum)0+Charge radius:5.5396(19) femtometer fmYear of discovery:1905

Radioactive Decay

Half-life T_½ = 10.64(1) h (hours) respectively 3.8304 × 10⁴ seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
β^-	²¹²Bi	100 %	0.5691(18) MeV

Parent Nuclides

Direct parent isotopes are: ²¹²Tl, ²¹⁶Po, ²²⁶Ra, ²³²Th.

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
^212mPb	+x keV	5(1) μs

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 130) and isobaric (same nucleon number A = 212) with Lead-212. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

Z	Isotone N = 130	Isobar A = 212
78	²⁰⁸Pt
79	²⁰⁹Au
80	²¹⁰Hg	²¹²Hg
81	²¹¹Tl	²¹²Tl
82	²¹²Pb	²¹²Pb
83	²¹³Bi	²¹²Bi
84	²¹⁴Po	²¹²Po
85	²¹⁵At	²¹²At
86	²¹⁶Rn	²¹²Rn
87	²¹⁷Fr	²¹²Fr
88	²¹⁸Ra	²¹²Ra
89	²¹⁹Ac	²¹²Ac
90	²²⁰Th	²¹²Th
91	²²¹Pa	²¹²Pa
92	²²²U
93	²²³Np