Astatine-207

Properties and data of the isotope ²⁰⁷At.

Contents

General Data

Radioactive Decay

Parent Nuclides

Isotones und Isobares

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

General data

Name of the isotope:Astatine-207; At-207Symbol:²⁰⁷At or 20785AtMass number A:207 (= number of nucleons)Atomic number Z:85 (= number of protons)Neutrons N:122Isotopic mass:206.985800(13) u (atomic weight of Astatine-207)Nuclide mass:206.9391763 u (calculated nuclear mass without electrons)Mass excess:-13.22721 MeVMass defect:1.736447472 u (per nucleus)Nuclear binding energy:1617.49040148 MeV (per nucleus)
7.81396329 MeV (average binding energy per nucleon)Separation energy:S_N = 8.869(19) MeV (first neutron)
S_P = 2.328(13) MeV (first proton)Half-life:1.81(3) hDecay constant λ:0.00010637617872313 s^-1Specific activity α:3.109768603944 × 10⁺¹⁷ Bq g^-1
8404780.0106603 Ci g^-1Spin and parity:
(nuclear angular momentum)9/2-Year of discovery:1951

Radioactive Decay

Half-life T_½ = 1.81(3) h (hours) respectively 6.516 × 10³ seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
α	²⁰³Bi	8.6(10) %	5.872(3) MeV
EC/β⁺	²⁰⁷Po	91.4(10) %	3.918(14) MeV

Parent Nuclides

Direct parent isotopes are: ²¹¹Fr, ²⁰⁷Rn.

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 122) and isobaric (same nucleon number A = 207) with Astatine-207. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

Z	Isotone N = 122	Isobar A = 207
74	¹⁹⁶W
75	¹⁹⁷Re
76	¹⁹⁸Os
77	¹⁹⁹Ir
78	²⁰⁰Pt	²⁰⁷Pt
79	²⁰¹Au	²⁰⁷Au
80	²⁰²Hg	²⁰⁷Hg
81	²⁰³Tl	²⁰⁷Tl
82	²⁰⁴Pb	²⁰⁷Pb
83	²⁰⁵Bi	²⁰⁷Bi
84	²⁰⁶Po	²⁰⁷Po
85	²⁰⁷At	²⁰⁷At
86	²⁰⁸Rn	²⁰⁷Rn
87	²⁰⁹Fr	²⁰⁷Fr
88	²¹⁰Ra	²⁰⁷Ra
89	²¹¹Ac	²⁰⁷Ac
90	²¹²Th	²⁰⁷Th
91	²¹³Pa
92	²¹⁴U