Actinium-232

Properties and data of the isotope ²³²Ac.

Contents

Actinium-232 is a radioisotope of the chemical element actinium, which, in addition to element-specific 89 protons, has 143 neutrons in the atomic nucleus, resulting in the mass number 232. The very short-lived, only artificially producible, unstable and therefore radioactive nuclide has no practical significance; dealing with ²³²Ac is for academic purposes only.

General data

Name of the isotope:Actinium-232; Ac-232Symbol:²³²Ac or 23289AcMass number A:232 (= number of nucleons)Atomic number Z:89 (= number of protons)Neutrons N:143Isotopic mass:232.042034(14) u (atomic weight of Actinium-232)Nuclide mass:231.9932166 u (calculated nuclear mass without electrons)Mass excess:39.15442 MeVMass defect:1.893476836 u (per nucleus)Nuclear binding energy:1763.76231187 MeV (per nucleus)
7.60242376 MeV (average binding energy per nucleon)Separation energy:S_N = 4.680(18) MeV (first neutron)
S_P = 6.351(17) MeV (first proton)Half-life:119(5) sDecay constant λ:0.0058247662231928 s^-1Specific activity α:1.511963908287 × 10⁺¹⁹ Bq g^-1
408638894.13176 Ci g^-1Spin and parity:
(nuclear angular momentum)(1+)Year of discovery:1986

Radioactive Decay

Half-life T_½ = 119(5) s respectively 1.19 × 10² seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
β^-	²³²Th	100 %	3.708(13) MeV

Parent Nuclides

Direct parent isotope is: ²³²Ra.

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 143) and isobaric (same nucleon number A = 232) with Actinium-232. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

Z	Isotone N = 143	Isobar A = 232
84	²²⁷Po
85	²²⁸At
86	²²⁹Rn
87	²³⁰Fr	²³²Fr
88	²³¹Ra	²³²Ra
89	²³²Ac	²³²Ac
90	²³³Th	²³²Th
91	²³⁴Pa	²³²Pa
92	²³⁵U	²³²U
93	²³⁶Np	²³²Np
94	²³⁷Pu	²³²Pu
95	²³⁸Am	²³²Am
96	²³⁹Cm	²³²Cm
97	²⁴⁰Bk
98	²⁴¹Cf
99	²⁴²Es
100	²⁴³Fm
101	²⁴⁴Md