Thallium-200m1

Properties and data of the isotope ²⁰⁰Tl.

Content

General data

Name of the isotope:Thallium-200m1; Tl-200m1Symbol:²⁰⁰Tl or 20081TlMass number A:200 (= number of nucleons)Atomic number Z:81 (= number of protons)Neutrons N:119Isotopic mass:199.970964(6) u (atomic weight of Thallium-200m1)
Excitation energy: 753.60(24) keVNuclide mass:199.926534 u (calculated nuclear mass without electrons)Mass excess:-27.04686 MeVMass defect:1.693988596 u (per nucleus)Nuclear binding energy:1577.94021324 MeV (per nucleus)
7.88970107 MeV (average binding energy per nucleon)Half-life:34.0(9) msDecay constant λ:20.386681781175 s^-1Specific activity α:6.169420570499 × 10⁺²² Bq g^-1
1667410964999.9 Ci g^-1Spin and parity:
(nuclear angular momentum)7+

Radioactive Decay

Half-life T_½ = 34.0(9) ms respectively 3.40 × 10^-2 seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
Iso	²⁰⁰Tl	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
²⁰⁰Tl		26.1(1) h	2-
^200m2Tl	762.00(24) keV	0.33(5) μs	5+

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 119) and isobaric (same nucleon number A = 200) with Thallium-200m1. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

OZ	Isotone N = 119	Isobar A = 200
73	¹⁹²Ta
74	¹⁹³W
75	¹⁹⁴Re
76	¹⁹⁵Os	²⁰⁰Os
77	¹⁹⁶Ir	²⁰⁰Ir
78	¹⁹⁷Pt	²⁰⁰Pt
79	¹⁹⁸Au	²⁰⁰Au
80	¹⁹⁹Hg	²⁰⁰Hg
81	²⁰⁰Tl	²⁰⁰Tl
82	²⁰¹Pb	²⁰⁰Pb
83	²⁰²Bi	²⁰⁰Bi
84	²⁰³Po	²⁰⁰Po
85	²⁰⁴At	²⁰⁰At
86	²⁰⁵Rn	²⁰⁰Rn
87	²⁰⁶Fr	²⁰⁰Fr
88	²⁰⁷Ra
89	²⁰⁸Ac
90	²⁰⁹Th