Radium-203

Properties and data of the isotope ²⁰³Ra.

Content

General data

Name of the isotope:Radium-203; Ra-203Symbol:²⁰³RaMass number A:203Atomic number Z:88 (= number of protons)Neutrons N:115Isotopic mass:203.00930(4) u (atomic weight of Radium-203)Nuclide mass:202.961031 u (calculated nuclear mass without electrons)Mass excess:8.66289 MeVMass defect:1.675768156 u (per nucleus)Nuclear binding energy:1560.96798271 MeV (per nucleus)
7.68949745 MeV (average binding energy per nucleon)Separation energy:S_N = 8.48(4) MeV (first neutron)
S_P = 1.72(4) MeV (first proton)Half-life:ca. 31 msDecay constant λ:22.359586469676 s^-1Spin and parity:(3/2-)Year of discovery:1996

Radioactive Decay

Half-life T_½ = ca. 31 ms respectively 3.1 × 10^-2 seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
α	¹⁹⁹Rn	~100 %	7,736(6) MeV
β⁺	²⁰³Fr	selten

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
^203mRa	220(90) keV	ca. 24 ms	(13/2+)

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 115) and isobaric (same nucleon number A = 203) with Radium-203. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

OZ	Isotone N = 115	Isobar A = 203
70	¹⁸⁵Yb
71	¹⁸⁶Lu
72	¹⁸⁷Hf
73	¹⁸⁸Ta
74	¹⁸⁹W
75	¹⁹⁰Re
76	¹⁹¹Os	²⁰³Os
77	¹⁹²Ir	²⁰³Ir
78	¹⁹³Pt	²⁰³Pt
79	¹⁹⁴Au	²⁰³Au
80	¹⁹⁵Hg	²⁰³Hg
81	¹⁹⁶Tl	²⁰³Tl
82	¹⁹⁷Pb	²⁰³Pb
83	¹⁹⁸Bi	²⁰³Bi
84	¹⁹⁹Po	²⁰³Po
85	²⁰⁰At	²⁰³At
86	²⁰¹Rn	²⁰³Rn
87	²⁰²Fr	²⁰³Fr
88	²⁰³Ra	²⁰³Ra
89	²⁰⁴Ac