Polonium-204

Properties and data of the isotope ²⁰⁴Po.

Content

General data

Name of the isotope:Polonium-204; Po-204Symbol:²⁰⁴Po or 20484PoMass number A:204 (= number of nucleons)Atomic number Z:84 (= number of protons)Neutrons N:120Isotopic mass:203.980310(12) u (atomic weight of Polonium-204)Nuclide mass:203.9342347 u (calculated nuclear mass without electrons)Mass excess:-18.34112 MeVMass defect:1.716782608 u (per nucleus)Nuclear binding energy:1599.17269866 MeV (per nucleus)
7.83908186 MeV (average binding energy per nucleon)Separation energy:S_N = 9.102(14) MeV (first neutron)
S_P = 4.105(17) MeV (first proton)Half-life:3.519(12) hDecay constant λ:5.471465856461 × 10^-5 s^-1Specific activity α:1.623149659997 × 10⁺¹⁷ Bq g^-1
4386890.9729657 Ci g^-1Spin and parity:
(nuclear angular momentum)0+Charge radius:5.5378(177) femtometer fmYear of discovery:1951

Radioactive Decay

Half-life T_½ = 3.519(12) h (hours) respectively 1.26684 × 10⁴ seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
α	²⁰⁰Pb	0.67(3) %	5.4849(14) MeV
EE/β⁺	²⁰⁴Bi	99.33(3) %	2.305(14) MeV

Parent Nuclides

Direct parent isotopes are: ²⁰⁸Rn, ²⁰⁴At.

Nuclear Isomers

Nuclear isomers or excited states with the activation energy in keV related to the ground state.

Nuclear Isomer	Excitation Energy	Half-life	Spin
^204mPo	1639.03(6) keV		8+

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 120) and isobaric (same nucleon number A = 204) with Polonium-204. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

OZ	Isotone N = 120	Isobar A = 204
73	¹⁹³Ta
74	¹⁹⁴W
75	¹⁹⁵Re
76	¹⁹⁶Os
77	¹⁹⁷Ir	²⁰⁴Ir
78	¹⁹⁸Pt	²⁰⁴Pt
79	¹⁹⁹Au	²⁰⁴Au
80	²⁰⁰Hg	²⁰⁴Hg
81	²⁰¹Tl	²⁰⁴Tl
82	²⁰²Pb	²⁰⁴Pb
83	²⁰³Bi	²⁰⁴Bi
84	²⁰⁴Po	²⁰⁴Po
85	²⁰⁵At	²⁰⁴At
86	²⁰⁶Rn	²⁰⁴Rn
87	²⁰⁷Fr	²⁰⁴Fr
88	²⁰⁸Ra	²⁰⁴Ra
89	²⁰⁹Ac	²⁰⁴Ac
90	²¹⁰Th