Francium-216

Properties and data of the isotope ²¹⁶Fr.

Contents

General Data

Radioactive Decay

Parent Nuclides

Isotones und Isobares

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

General data

Name of the isotope:Francium-216; Fr-216Symbol:²¹⁶Fr or 21687FrMass number A:216 (= number of nucleons)Atomic number Z:87 (= number of protons)Neutrons N:129Nucleon pairing (Z - N):odd - oddNuclear ratio (N/Z ratio):1.4827586206897 (= neutron-proton ratio)Neutron excess (N-Z):42Isotopic mass:216.003189(4) u (atomic weight of Francium-216)Nuclide mass:215.9554684 u (calculated nuclear mass without electrons)Mass excess:2.97053 MeVMass defect:1.795362948 u (per nucleus)Nuclear binding energy:1672.36981388 MeV (per nucleus)
7.74245284 MeV (average binding energy per nucleon)Separation energy:S_N = 5.418(8) MeV (first neutron)
S_P = 3.149(9) MeV (first proton)Half-life:0.70(2) μsDecay constant λ:990210.25794278 s^-1Specific activity α:2.760734099206 × 10⁺²⁷ Bq g^-1
7.461443511368 × 10⁺¹⁶ Ci g^-1Spin and parity:
(nuclear angular momentum)(1-)Year of discovery:1970

Radioactive Decay

Half-life T_½ = 0.70(2) μs respectively 7.0 × 10^-7 seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
α	²¹²At	ca. 100 %	9.174(3) MeV
EC	²¹⁶Rn	<< 1 %	2.718(7) MeV

Parent Nuclides

Direct parent isotope is: ²²⁰Ac.

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
^216mFr	219(6) keV	850(30) ns	(9-)

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 129) and isobaric (same nucleon number A = 216) with Francium-216. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

Z	Isotone N = 129	Isobar A = 216
78	²⁰⁷Pt
79	²⁰⁸Au
80	²⁰⁹Hg	²¹⁶Hg
81	²¹⁰Tl	²¹⁶Tl
82	²¹¹Pb	²¹⁶Pb
83	²¹²Bi	²¹⁶Bi
84	²¹³Po	²¹⁶Po
85	²¹⁴At	²¹⁶At
86	²¹⁵Rn	²¹⁶Rn
87	²¹⁶Fr	²¹⁶Fr
88	²¹⁷Ra	²¹⁶Ra
89	²¹⁸Ac	²¹⁶Ac
90	²¹⁹Th	²¹⁶Th
91	²²⁰Pa	²¹⁶Pa
92	²²¹U	²¹⁶U
93	²²²Np