Protactinium-235

Properties and data of the isotope ²³⁵Pa.

Contents

General Data

Radioactive Decay

Parent Nuclides

Isotones und Isobares

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

General data

Name of the isotope:Protactinium-235; Pa-235Symbol:²³⁵Pa or 23591PaMass number A:235 (= number of nucleons)Atomic number Z:91 (= number of protons)Neutrons N:144Nucleon pairing (Z - N):odd - evenNuclear ratio (N/Z ratio):1.5824175824176 (= neutron-proton ratio)Neutron excess (N-Z):53Isotopic mass:235.045399(15) u (atomic weight of Protactinium-235)Nuclide mass:234.9954847 u (calculated nuclear mass without electrons)Mass excess:42.2889 MeVMass defect:1.914426816 u (per nucleus)Nuclear binding energy:1783.27709254 MeV (per nucleus)
7.58841316 MeV (average binding energy per nucleon)Separation energy:S_N = 6.121(15) MeV (first neutron)
S_P = 5.613(14) MeV (first proton)Half-life:24.4(2) minDecay constant λ:0.00047346118890707 s^-1Specific activity α:1.213297860132 × 10⁺¹⁸ Bq g^-1
32791834.057635 Ci g^-1Spin and parity:
(nuclear angular momentum)(3/2-)Year of discovery:1950

Radioactive Decay

Half-life T_½ = 24.4(2) min (minutes) respectively 1.464 × 10³ seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
β^-	²³⁵U	100 %	1.370(14) MeV

Parent Nuclides

Direct parent isotope is: ²³⁵Th.

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 144) and isobaric (same nucleon number A = 235) with Protactinium-235. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

Z	Isotone N = 144	Isobar A = 235
85	²²⁹At
86	²³⁰Rn
87	²³¹Fr
88	²³²Ra
89	²³³Ac	²³⁵Ac
90	²³⁴Th	²³⁵Th
91	²³⁵Pa	²³⁵Pa
92	²³⁶U	²³⁵U
93	²³⁷Np	²³⁵Np
94	²³⁸Pu	²³⁵Pu
95	²³⁹Am	²³⁵Am
96	²⁴⁰Cm	²³⁵Cm
97	²⁴¹Bk	²³⁵Bk
98	²⁴²Cf
99	²⁴³Es
100	²⁴⁴Fm
101	²⁴⁵Md