Radium-215

Properties and data of the isotope ²¹⁵Ra.

Contents

General Data

Radioactive Decay

Parent Nuclides

Isotones und Isobares

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

General data

Name of the isotope:Radium-215; Ra-215Symbol: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-215)Nuclide 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)Separation energy:S_N = 5.63(9) MeV (first neutron)
S_P = 3.797(11) MeV (first proton)Half-life:1.66(2) msDecay constant λ:417.55854250599 s^-1Specific activity α:1.169579702437 × 10⁺²⁴ Bq g^-1
31610262228046 Ci g^-1Spin and parity:
(nuclear angular momentum)(9/2+)Year of discovery:1967

Radioactive Decay

Half-life T_½ = 1.66(2) ms respectively 1.66 × 10^-3 seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
α	²¹¹Rn	100 %	8.864(3) MeV

Parent Nuclides

Direct parent isotopes are: ²¹⁹Th, ²¹⁵Ac.

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
^215m1Ra	1877.8(3) keV	7.29(20) μs	(25/2+)
^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-215. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

Z	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
93	²²⁰Np