Uranium-221

Properties and data of the isotope ²²¹U.

Contents

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

General data

Name of the isotope:Uranium-221; U-221Symbol:²²¹U or 22192UMass number A:221 (= number of nucleons)Atomic number Z:92 (= number of protons)Neutrons N:129Nucleon pairing (Z - N):even - oddNuclear ratio (N/Z ratio):1.4021739130435 (= neutron-proton ratio)Neutron excess (N-Z):37Isotopic mass:221.026320(80) u (atomic weight of Uranium-221)Nuclide mass:220.9758573 u (calculated nuclear mass without electrons)Mass excess:24.51692 MeVMass defect:1.811357108 u (per nucleus)Nuclear binding energy:1687.26827796 MeV (per nucleus)
7.63469809 MeV (average binding energy per nucleon)Separation energy:S_N = 6.565(12) MeV (first neutron)
S_P = 3.047(74) MeV (first proton)Half-life:0.66(14) μsDecay constant λ:1050223.0008484 s^-1Specific activity α:2.861805812422 × 10⁺²⁷ Bq g^-1
7.734610303845 × 10⁺¹⁶ Ci g^-1Spin and parity:
(nuclear angular momentum)(9/2+)Year of discovery:2015

Radioactive Decay

Half-life T_½ = 0.66(14) μs respectively 6.6 × 10^-7 seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
α	²¹⁷Th	~100 %	9.889(71) MeV

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 129) and isobaric (same nucleon number A = 221) with Uranium-221. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

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