Francium-207

Properties and data of the isotope ²⁰⁷Fr.

Contents

General Data

Radioactive Decay

Parent Nuclides

Isotones und Isobares

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

General data

Name of the isotope:Francium-207; Fr-207Symbol:²⁰⁷Fr or 20787FrMass number A:207 (= number of nucleons)Atomic number Z:87 (= number of protons)Neutrons N:120Isotopic mass:206.996946(19) u (atomic weight of Francium-207)Nuclide mass:206.9492254 u (calculated nuclear mass without electrons)Mass excess:-2.84478 MeVMass defect:1.723621704 u (per nucleus)Nuclear binding energy:1605.54327555 MeV (per nucleus)
7.75624771 MeV (average binding energy per nucleon)Separation energy:S_N = 9.67(3) MeV (first neutron)
S_P = 1.000(19) MeV (first proton)Half-life:14.8(1) sDecay constant λ:0.046834268956753 s^-1Specific activity α:1.369138663736 × 10⁺²⁰ Bq g^-1
3700374766.8557 Ci g^-1Spin and parity:
(nuclear angular momentum)9/2-Magnetic dipole moment:μ(μ_N) = + 3.89(8)Quadrupole moment Q:-0.16(5) barn (100 fm²)Nuclear g-factor:g_l = 0.86444444444444Charge radius:5.5720(176) femtometer fmYear of discovery:1964

Radioactive Decay

Half-life T_½ = 14.8(1) s respectively 1.48 × 10¹ seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
α	²⁰³At	95(2) %	6.893(20) MeV
EC/β⁺	²⁰⁷Rn	5(2) %	5.79(19) MeV

Parent Nuclides

Direct parent isotope is: ²¹¹Ac.

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 120) and isobaric (same nucleon number A = 207) with Francium-207. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

Z	Isotone N = 120	Isobar A = 207
73	¹⁹³Ta
74	¹⁹⁴W
75	¹⁹⁵Re
76	¹⁹⁶Os
77	¹⁹⁷Ir
78	¹⁹⁸Pt	²⁰⁷Pt
79	¹⁹⁹Au	²⁰⁷Au
80	²⁰⁰Hg	²⁰⁷Hg
81	²⁰¹Tl	²⁰⁷Tl
82	²⁰²Pb	²⁰⁷Pb
83	²⁰³Bi	²⁰⁷Bi
84	²⁰⁴Po	²⁰⁷Po
85	²⁰⁵At	²⁰⁷At
86	²⁰⁶Rn	²⁰⁷Rn
87	²⁰⁷Fr	²⁰⁷Fr
88	²⁰⁸Ra	²⁰⁷Ra
89	²⁰⁹Ac	²⁰⁷Ac
90	²¹⁰Th	²⁰⁷Th