Actinium-213 is a radioisotope of the chemical element actinium, which, in addition to element-specific 89 protons, has 124 neutrons in the atomic nucleus, resulting in the mass number 213. The very short-lived, only artificially producible, unstable and therefore radioactive nuclide has no practical significance; dealing with 213Ac is for academic purposes only.
See also: List of individual Actinium isotopes (and general data sources).
General data
Name of the isotope:Actinium-213; Ac-213Symbol:213Ac or 21389AcMass number A:213 (= number of nucleons)Atomic number Z:89 (= number of protons)Neutrons N:124Nucleon pairing (Z - N):odd - evenNuclear ratio (N/Z ratio):1.3932584269663 (= neutron-proton ratio)Neutron excess (N-Z):35Isotopic mass:213.006607(16) u (atomic weight of Actinium-213)Nuclide mass:212.9577896 u (calculated nuclear mass without electrons)Mass excess:6.15438 MeVMass defect:1.764270432 u (per nucleus)Nuclear binding energy:1643.40732179 MeV (per nucleus) 7.71552733 MeV (average binding energy per nucleon)Separation energy:SN = 9.19(5) MeV (first neutron) SP = 0.935(19) MeV (first proton)Half-life:738(16) msDecay constant λ:0.93922382189694 s-1Specific activity α:2.655381511526 × 10+21 Bq g-1 71767067879.103 Ci g-1Spin and parity: (nuclear angular momentum)(9/2-)Magnetic dipole moment:μ(μN) = +4.2(4)Nuclear g-factor:gl = 0.93333333333333Year of discovery:1968
Radioactive Decay
Half-life T½ = 738(16) ms respectively 7.38 × 10-1 seconds s.
The following table shows the atomic nuclei that are isotonic (same neutron number N = 124) and isobaric (same nucleon number A = 213) with Actinium-213. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.
