Francium-202

Properties and data of the isotope ²⁰²Fr.

Content

General data

Name of the isotope:Francium-202; Fr-202Symbol:²⁰²Fr or 20287FrMass number A:202 (= number of nucleons)Atomic number Z:87 (= number of protons)Neutrons N:115Isotopic mass:202.003324(8) u (atomic weight of Francium-202)Nuclide mass:201.9556034 u (calculated nuclear mass without electrons)Mass excess:3.09629 MeVMass defect:1.673919124 u (per nucleus)Nuclear binding energy:1559.24562049 MeV (per nucleus)
7.71903773 MeV (average binding energy per nucleon)Separation energy:S_N = 8.564(11) MeV (first neutron)
S_P = 0.12(5) MeV (first proton)Half-life:0.30(5) sDecay constant λ:2.3104906018665 s^-1Specific activity α:6.888168247524 × 10⁺²¹ Bq g^-1
186166709392.56 Ci g^-1Spin and parity:
(nuclear angular momentum)(3+)Year of discovery:1980

Radioactive Decay

Half-life T_½ = 0.30(5) s respectively 3.0 × 10^-1 seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
α	¹⁹⁸At	100 %	7.386(4) MeV

Parent Nuclides

Direct parent isotope is: ²⁰⁶Ac.

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
^202mFr	+x keV	0.29(5) 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 = 202) with Francium-202. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

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