See also: List of individual Mercury isotopes (and general data sources).
General data
Name of the isotope:Mercury-185m; Hg-185mSymbol:185mHg or 185m80HgMass number A:185 (= number of nucleons)Atomic number Z:80 (= number of protons)Neutrons N:105Nucleon pairing (Z - N):even - oddNuclear ratio (N/Z ratio):1.3125 (= neutron-proton ratio)Neutron excess (N-Z):25Excitation energy:99.3(5) keVIsotopic mass:184.971891(15) u (atomic weight of Mercury-185m)Nuclide mass:184.9280094 u (calculated nuclear mass without electrons)Mass excess:-26.18336 MeVMass defect:1.56392774 u (per nucleus)Nuclear binding energy:1456.78930624 MeV (per nucleus) 7.87453679 MeV (average binding energy per nucleon)Half-life:21.6(15) sDecay constant λ:0.032090147248146 s-1Specific activity α:1.044760815779 × 10+20 Bq g-1 2823677880.4854 Ci g-1Spin and parity: (nuclear angular momentum)13/2+Magnetic dipole moment:μ(μN) = - 1.017(9)Quadrupole moment Q:+0.2(3) barn (100 fm2)Nuclear g-factor:gl = -0.15646153846154
Radioactive Decay
Half-life T½ = 21.6(15) s respectively 2.16 × 101 seconds s.
Decay mode
Daughter
Probability
Decay energy
γ energy (intensity)
α
181Pt
ca. 0.03 %
EC/β+
185Au
46(10) %
Iso
185Hg
54(10) %
Nuclear Isomers
Nuclear isomers or excited states with the activation energy in keV related to the ground state.
The following table shows the atomic nuclei that are isotonic (same neutron number N = 105) and isobaric (same nucleon number A = 185) with Mercury-185m. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.
