Astatine-200m1

Properties and data of the isotope ^200m1At.

Contents

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

General data

Name of the isotope:Astatine-200m1; At-200m1Symbol:^200m1At or 200m185AtMass number A:200 (= number of nucleons)Atomic number Z:85 (= number of protons)Neutrons N:115Isotopic mass:199.990351(26) u (atomic weight of Astatine-200m1)
Excitation energy: 112(5) keVNuclide mass:199.9437273 u (calculated nuclear mass without electrons)Mass excess:-8.98799 MeVMass defect:1.67124206 u (per nucleus)Nuclear binding energy:1556.75195144 MeV (per nucleus)
7.78375976 MeV (average binding energy per nucleon)Half-life:47(1) sDecay constant λ:0.014747812352339 s^-1Specific activity α:4.462985093552 × 10⁺¹⁹ Bq g^-1
1206212187.4467 Ci g^-1Spin and parity:
(nuclear angular momentum)(7+)

Radioactive Decay

Half-life T_½ = 47(1) s respectively 4.7 × 10¹ seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
α	¹⁹⁶Bi	43(7) %
EC/β⁺	²⁰⁰Po	≤ 57 %

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
²⁰⁰At		43(1) s	(3+)
^200m2At	344(5) keV	ca. 7.3 s	(10-)

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 115) and isobaric (same nucleon number A = 200) with Astatine-200m1. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

Z	Isotone N = 115	Isobar A = 200
70	¹⁸⁵Yb
71	¹⁸⁶Lu
72	¹⁸⁷Hf
73	¹⁸⁸Ta
74	¹⁸⁹W
75	¹⁹⁰Re
76	¹⁹¹Os	²⁰⁰Os
77	¹⁹²Ir	²⁰⁰Ir
78	¹⁹³Pt	²⁰⁰Pt
79	¹⁹⁴Au	²⁰⁰Au
80	¹⁹⁵Hg	²⁰⁰Hg
81	¹⁹⁶Tl	²⁰⁰Tl
82	¹⁹⁷Pb	²⁰⁰Pb
83	¹⁹⁸Bi	²⁰⁰Bi
84	¹⁹⁹Po	²⁰⁰Po
85	²⁰⁰At	²⁰⁰At
86	²⁰¹Rn	²⁰⁰Rn
87	²⁰²Fr	²⁰⁰Fr
88	²⁰³Ra
89	²⁰⁴Ac