See also: List of individual Francium isotopes (and general data sources).
General data
Name of the isotope:Francium-216; Fr-216Symbol:216Fr or 21687FrMass number A:216 (= number of nucleons)Atomic number Z:87 (= number of protons)Neutrons N:129Nucleon pairing (Z - N):odd - oddNuclear ratio (N/Z ratio):1.4827586206897 (= neutron-proton ratio)Neutron excess (N-Z):42Isotopic mass:216.003190(4) u (atomic weight of Francium-216)Nuclide mass:215.9554694 u (calculated nuclear mass without electrons)Mass excess:2.97147 MeVMass defect:1.795361948 u (per nucleus)Nuclear binding energy:1672.36888239 MeV (per nucleus) 7.74244853 MeV (average binding energy per nucleon)Separation energy:SN = 5.418(8) MeV (first neutron) SP = 3.149(7) MeV (first proton)Half-life:0.70(2) μsDecay constant λ:990210.25794278 s-1Specific activity α:2.760693282042 × 10+27 Bq g-1 7.461333194709 × 10+16 Ci g-1Spin and parity: (nuclear angular momentum)(1-)Year of discovery:1970
The following table shows the atomic nuclei that are isotonic (same neutron number N = 129) and isobaric (same nucleon number A = 216) with Francium-216. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.
