Name of the isotope:Rutherfordium-255; Rf-255Symbol:255Rf or 255104RfMass number A:255 (= number of nucleons)Atomic number Z:104 (= number of protons)Neutrons N:151Nucleon pairing (Z - N):even - oddNuclear ratio (N/Z ratio):1.4519230769231 (= neutron-proton ratio)Neutron excess (N-Z):47Isotopic mass:255.10127(12) u (atomic weight of Rutherfordium-255)Nuclide mass:255.0442266 u (calculated nuclear mass without electrons)Mass excess:94.3324 MeVMass defect:2.020935644 u (per nucleus)Nuclear binding energy:1882.48942677 MeV (per nucleus) 7.38231148 MeV (average binding energy per nucleon)Separation energy:SN = 6.94(31) MeV (first neutron) SP = 2.83(32) MeV (first proton)Half-life:1.68(19) sDecay constant λ:0.41258760747616 s-1Specific activity α:9.739899170447 × 10+20 Bq g-1 26324051812.02 Ci g-1Spin and parity: (nuclear angular momentum)(9/2-)Year of discovery:1975
The following table shows the atomic nuclei that are isotonic (same neutron number N = 151) and isobaric (same nucleon number A = 255) with Rutherfordium-255. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.
