Thorium-211

Properties and data of the isotope ²¹¹Th.

Contents

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

General data

Name of the isotope:Thorium-211; Th-211Symbol:²¹¹Th or 21190ThMass number A:211 (= number of nucleons)Atomic number Z:90 (= number of protons)Neutrons N:121Nucleon pairing (Z - N):even - oddNuclear ratio (N/Z ratio):1.3444444444444 (= neutron-proton ratio)Neutron excess (N-Z):31Isotopic mass:211.01493(8) u (atomic weight of Thorium-211)Nuclide mass:210.9655642 u (calculated nuclear mass without electrons)Mass excess:13.90721 MeVMass defect:1.737777716 u (per nucleus)Nuclear binding energy:1618.72951579 MeV (per nucleus)
7.67170387 MeV (average binding energy per nucleon)Separation energy:S_N = 8.22(8) MeV (first neutron)
S_P = 2.17(9) MeV (first proton)Half-life:37 msDecay constant λ:18.733707582701 s^-1Specific activity α:5.346778478288 × 10⁺²² Bq g^-1
1445075264402.4 Ci g^-1Spin and parity:
(nuclear angular momentum)Year of discovery:1995

Radioactive Decay

Half-life T_½ = 37 ms respectively 3.7 × 10^-2 seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
α	²⁰⁷Ra	?	7.94(5) MeV
&epsilon	²¹¹Ac	?	6.71(9) MeV

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 121) and isobaric (same nucleon number A = 211) with Thorium-211. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

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