Polonium-225

Properties and data of the isotope ²²⁵Po.

Contents

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

General data

Name of the isotope:Polonium-225; Po-225Symbol:²²⁵Po or 22584PoMass number A:225 (= number of nucleons)Atomic number Z:84 (= number of protons)Neutrons N:141Nucleon pairing (Z - N):even - oddNuclear ratio (N/Z ratio):1.6785714285714 (= neutron-proton ratio)Neutron excess (N-Z):57Isotopic mass:225.03707(32) u (atomic weight of Polonium-225)Nuclide mass:224.9909947 u (calculated nuclear mass without electrons)Mass excess:34.53048 MeVMass defect:1.841985844 u (per nucleus)Nuclear binding energy:1715.79876177 MeV (per nucleus)
7.62577227 MeV (average binding energy per nucleon)Separation energy:S_N = 3.45(36) MeV (first neutron)
S_P = 9.59(50) MeV (first proton)Half-life:300 nsDecay constant λ:2310490.6018665 s^-1Specific activity α:6.184044382222 × 10⁺²⁷ Bq g^-1
1.671363346546 × 10⁺¹⁷ Ci g^-1Spin and parity:
(nuclear angular momentum)Year of discovery:2010

Radioactive Decay

Half-life T_½ = 300 ns respectively 3.0 × 10^-7 seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
β^-	²²⁵At	?	4.14(42) MeV

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 141) and isobaric (same nucleon number A = 225) with Polonium-225. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

Z	Isotone N = 141	Isobar A = 225
83	²²⁴Bi
84	²²⁵Po	²²⁵Po
85	²²⁶At	²²⁵At
86	²²⁷Rn	²²⁵Rn
87	²²⁸Fr	²²⁵Fr
88	²²⁹Ra	²²⁵Ra
89	²³⁰Ac	²²⁵Ac
90	²³¹Th	²²⁵Th
91	²³²Pa	²²⁵Pa
92	²³³U	²²⁵U
93	²³⁴Np	²²⁵Np
94	²³⁵Pu
95	²³⁶Am
96	²³⁷Cm
97	²³⁸Bk
98	²³⁹Cf
99	²⁴⁰Es
100	²⁴¹Fm