See also: List of individual Rhenium isotopes (and general data sources).
General data
Name of the isotope:Rhenium-181; Re-181Symbol:181Re or 18175ReMass number A:181 (= number of nucleons)Atomic number Z:75 (= number of protons)Neutrons N:106Nucleon pairing (Z - N):odd - evenNuclear ratio (N/Z ratio):1.4133333333333 (= neutron-proton ratio)Neutron excess (N-Z):31Isotopic mass:180.950062(13) u (atomic weight of Rhenium-181)Nuclide mass:180.9089227 u (calculated nuclear mass without electrons)Mass excess:-46.51695 MeVMass defect:1.555296496 u (per nucleus)Nuclear binding energy:1448.74935425 MeV (per nucleus) 8.00414008 MeV (average binding energy per nucleon)Separation energy:SN = 8.751(25) MeV (first neutron) SP = 4.170(13) MeV (first proton)Half-life:19.9(7) hDecay constant λ:9.675421280847 × 10-6 s-1Specific activity α:3.220045808305 × 10+16 Bq g-1 870282.65089327 Ci g-1Spin and parity: (nuclear angular momentum)5/2+Magnetic dipole moment:μ(μN) = 3.19(7)Nuclear g-factor:gl = 1.276Year of discovery:1957
Radioactive Decay
Half-life T½ = 19.9(7) h (hours) respectively 7.1640 × 104 seconds s.
The following table shows the atomic nuclei that are isotonic (same neutron number N = 106) and isobaric (same nucleon number A = 181) with Rhenium-181. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.
