Actinium-210

Properties and data of the isotope ²¹⁰Ac.

Content

Actinium-210 is a radioisotope of the chemical element actinium, which, in addition to element-specific 89 protons, has 121 neutrons in the atomic nucleus, resulting in the mass number 210. The very short-lived, only artificially producible, unstable and therefore radioactive nuclide has no practical significance; dealing with ²¹⁰Ac is for academic purposes only.

General data

Name of the isotope:Actinium-210; Ac-210Symbol:²¹⁰Ac or 21089AcMass number A:210 (= number of nucleons)Atomic number Z:89 (= number of protons)Neutrons N:121Isotopic mass:210.00944(6) u (atomic weight of Actinium-210)Nuclide mass:209.9606226 u (calculated nuclear mass without electrons)Mass excess:8.7933 MeVMass defect:1.735442684 u (per nucleus)Nuclear binding energy:1616.55444749 MeV (per nucleus)
7.69787832 MeV (average binding energy per nucleon)Separation energy:S_N = 8.13(8) MeV (first neutron)
S_P = 0.36(6) MeV (first proton)Half-life:0.35(5) sDecay constant λ:1.9804205158856 s^-1Specific activity α:5.679224432653 × 10⁺²¹ Bq g^-1
153492552233.87 Ci g^-1Spin and parity:
(nuclear angular momentum)7+Year of discovery:1968

Radioactive Decay

Half-life T_½ = 0.35(5) s respectively 3.5 × 10^-1 seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
α	²⁰⁶Fr	91 %	7.61(5) MeV
EE/β⁺	²¹⁰Ra	9 %	8.35(6) MeV

Parent Nuclides

Direct parent isotopes are: ²¹⁴Pa, ²¹⁰Th.

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 121) and isobaric (same nucleon number A = 210) with Actinium-210. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

OZ	Isotone N = 121	Isobar A = 210
73	¹⁹⁴Ta
74	¹⁹⁵W
75	¹⁹⁶Re
76	¹⁹⁷Os
77	¹⁹⁸Ir
78	¹⁹⁹Pt
79	²⁰⁰Au	²¹⁰Au
80	²⁰¹Hg	²¹⁰Hg
81	²⁰²Tl	²¹⁰Tl
82	²⁰³Pb	²¹⁰Pb
83	²⁰⁴Bi	²¹⁰Bi
84	²⁰⁵Po	²¹⁰Po
85	²⁰⁶At	²¹⁰At
86	²⁰⁷Rn	²¹⁰Rn
87	²⁰⁸Fr	²¹⁰Fr
88	²⁰⁹Ra	²¹⁰Ra
89	²¹⁰Ac	²¹⁰Ac
90	²¹¹Th	²¹⁰Th
91	²¹²Pa