Protactinium-210

Properties and data of the isotope ²¹⁰Pa.

Contents

Protactinium-210 is a radioisotope of the chemical element protactinium, which has 119 neutrons in its atomic nucleus in addition to the element-specific 91 protons; the sum of the number of these atomic nucleus building blocks results in a mass number of 210. The very short-lived, only artificially produced, unstable and thus radioactive nuclide has no practical significance; the study of ²¹⁰Pa is exclusively for academic purposes.

The discovery of the α-emitter was reported in 2025; a Chinese research group reported the observation of the neutron-poor isotope protactinium-210 after it was produced by the fusion-evaporation reaction ¹⁷⁵Lu(⁴⁰Ca,5n)²¹⁰Pa in a superheavy element accelerator [1]. The half-life was given as T = 6.0+1.5-1.1 ms.

See also: List of individual Protactinium isotopes (and general data sources).

General data

Name of the isotope:Protactinium-210; Pa-210Symbol:²¹⁰Pa or 21091PaMass number A:210 (= number of nucleons)Atomic number Z:91 (= number of protons)Neutrons N:119Isotopic mass:210 u (atomic weight of Protactinium-210)Nuclide mass:209.9500857 u (calculated nuclear mass without electrons)Mass excess:0 MeVMass defect:1.743202916 u (per nucleus)Nuclear binding energy:1623.78305704 MeV (per nucleus)
7.73230027 MeV (average binding energy per nucleon)Half-life:6.0 msDecay constant λ:115.52453009332 s^-1Specific activity α:3.312880919047 × 10⁺²³ Bq g^-1
8953732213642.2 Ci g^-1Spin and parity:
(nuclear angular momentum)3+Year of discovery:2025

Radioactive Decay

Half-life T_½ = 6.0 ms respectively 6 × 10^-3 seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
α	²⁰⁶Ac	100 %	8.284(15) MeV

Production and radioactive decay of Pa-210

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 119) and isobaric (same nucleon number A = 210) with Protactinium-210. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

Z	Isotone N = 119	Isobar A = 210
73	¹⁹²Ta
74	¹⁹³W
75	¹⁹⁴Re
76	¹⁹⁵Os
77	¹⁹⁶Ir
78	¹⁹⁷Pt
79	¹⁹⁸Au	²¹⁰Au
80	¹⁹⁹Hg	²¹⁰Hg
81	²⁰⁰Tl	²¹⁰Tl
82	²⁰¹Pb	²¹⁰Pb
83	²⁰²Bi	²¹⁰Bi
84	²⁰³Po	²¹⁰Po
85	²⁰⁴At	²¹⁰At
86	²⁰⁵Rn	²¹⁰Rn
87	²⁰⁶Fr	²¹⁰Fr
88	²⁰⁷Ra	²¹⁰Ra
89	²⁰⁸Ac	²¹⁰Ac
90	²⁰⁹Th	²¹⁰Th
91	²¹⁰Pa	²¹⁰Pa

Literature and References

[1] - M. M. Zhang, J. G. Wang, L. Ma et al.:
Discovery of the α-emitting isotope ²¹⁰Pa.
In: Natur Communications, 16, 5003, (2025), DOI 10.1038/s41467-025-60047-2.