Bismuth-212

Properties and data of the isotope ²¹²Bi.

Contents

Bismuth-212 is the radioisotope of the element Bismuth, whose atomic nucleus has 129 neutrons in addition to the element-specific 83 protons, resulting in a mass number of 212.

General data

Name of the isotope:Bismuth-212; Bi-212Other names:Thorium CSymbol:²¹²Bi or 21283BiMass number A:212 (= number of nucleons)Atomic number Z:83 (= number of protons)Neutrons N:129Isotopic mass:211.991285(2) u (atomic weight of Bismuth-212)Nuclide mass:211.9457581 u (calculated nuclear mass without electrons)Mass excess:-8.11797 MeVMass defect:1.77596682 u (per nucleus)Nuclear binding energy:1654.30243703 MeV (per nucleus)
7.80331338 MeV (average binding energy per nucleon)Separation energy:S_N = 4.330(6) MeV (first neutron)
S_P = 4.9140(27) MeV (first proton)Half-life:60.55(6) minDecay constant λ:0.00019079195721441 s^-1Specific activity α:5.445384081934 × 10⁺¹⁷ Bq g^-1
14717254.275499 Ci g^-1Spin and parity:
(nuclear angular momentum)1(-)Magnetic dipole moment:μ(μ_N) = 0.41(5)Quadrupole moment Q:+ 0.10(3) barn (100 fm²)Nuclear g-factor:g_l = 0.41Charge radius:5.5489(901) femtometer fmYear of discovery:1905

Radioactive Decay

Half-life T_½ = 60.55(6) min (minutes) respectively 3.633 × 10³ seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
β^-	²¹²Po	64.06(6) %	2.2515(17) MeV
α	²⁰⁸Tl	35.94(6) %	6.20726(3) MeV

Bi-212 is a radioactive intermediate of the thorium series emanating from Thorium-232 (see there for complete decay scheme).

Parent Nuclides

Direct parent isotopes are: ²¹⁶At, ²¹²Pb.

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
^212m1Bi	250 keV	25.0(2) min	(8-,9-)
^212m2Bi	1910 keV	7.0(3) min

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 129) and isobaric (same nucleon number A = 212) with Bismuth-212. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

Z	Isotone N = 129	Isobar A = 212
78	²⁰⁷Pt
79	²⁰⁸Au
80	²⁰⁹Hg	²¹²Hg
81	²¹⁰Tl	²¹²Tl
82	²¹¹Pb	²¹²Pb
83	²¹²Bi	²¹²Bi
84	²¹³Po	²¹²Po
85	²¹⁴At	²¹²At
86	²¹⁵Rn	²¹²Rn
87	²¹⁶Fr	²¹²Fr
88	²¹⁷Ra	²¹²Ra
89	²¹⁸Ac	²¹²Ac
90	²¹⁹Th	²¹²Th
91	²²⁰Pa	²¹²Pa
92	²²¹U