Lead-212m

Properties and data of the isotope ^212mPb.

Contents

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

General data

Name of the isotope:Lead-212m; Pb-212mSymbol:^212mPb or 212m82PbMass number A:212 (= number of nucleons)Atomic number Z:82 (= number of protons)Neutrons N:130Nucleon pairing (Z - N):even - evenNuclear ratio (N/Z ratio):1.5853658536585 (= neutron-proton ratio)Neutron excess (N-Z):48Excitation energy:+x keVIsotopic mass:211.991896(2) u (atomic weight of Lead-212m)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)Half-life:5(1) μsDecay constant λ:138629.43611199 s^-1Specific activity α:3.956616073933 × 10⁺²⁶ Bq g^-1
1.069355695657 × 10⁺¹⁶ Ci g^-1Spin and parity:
(nuclear angular momentum)

Radioactive Decay

Half-life T_½ = 5(1) μs respectively 5 × 10^-6 seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
Iso	²¹²Pb	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
²¹²Pb		10.622(7) h	0+

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-212m. 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