Radium-215m1

Properties and data of the isotope ²¹⁵Ra.

Content

General data

Name of the isotope:Radium-215m1; Ra-215m1Symbol:²¹⁵Ra or 21588RaMass number A:215 (= number of nucleons)Atomic number Z:88 (= number of protons)Neutrons N:127Isotopic mass:215.002720(8) u (atomic weight of Radium-215m1)
Excitation energy: 1877.8(3) keVNuclide mass:214.954451 u (calculated nuclear mass without electrons)Mass excess:2.53366 MeVMass defect:1.786327148 u (per nucleus)Nuclear binding energy:1663.9530204 MeV (per nucleus)
7.73931637 MeV (average binding energy per nucleon)Half-life:7.29(20) μsDecay constant λ:95081.917772283 s^-1Specific activity α:2.663240474686 × 10⁺²⁶ Bq g^-1
7.197947228882 × 10⁺¹⁵ Ci g^-1Spin and parity:
(nuclear angular momentum)(25/2+)

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
²¹⁵Ra		1.66(2) ms	(9/2+)
^215m2Ra	2246.9(4) keV	1.39(7) μs	(29/2-)
^215m3Ra	3756.6(4)+x keV	0.555(10) μs	(43/2-)

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 127) and isobaric (same nucleon number A = 215) with Radium-215m1. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

OZ	Isotone N = 127	Isobar A = 215
76	²⁰³Os
77	²⁰⁴Ir
78	²⁰⁵Pt
79	²⁰⁶Au
80	²⁰⁷Hg	²¹⁵Hg
81	²⁰⁸Tl	²¹⁵Tl
82	²⁰⁹Pb	²¹⁵Pb
83	²¹⁰Bi	²¹⁵Bi
84	²¹¹Po	²¹⁵Po
85	²¹²At	²¹⁵At
86	²¹³Rn	²¹⁵Rn
87	²¹⁴Fr	²¹⁵Fr
88	²¹⁵Ra	²¹⁵Ra
89	²¹⁶Ac	²¹⁵Ac
90	²¹⁷Th	²¹⁵Th
91	²¹⁸Pa	²¹⁵Pa
92	²¹⁹U	²¹⁵U