Lawrencium-251

Properties and data of the isotope ²⁵¹Lr.

Content

Lawrencium-251 is a radioisotope of the element lawrencium, whose atomic nucleus has 148 neutrons in addition to the element-specific 103 protons, resulting in a mass number of ²⁵¹Lr.

The generation and detection of the unstable and short-lived isotope was first reported in 2022. It was produced using the Argonne Gas-Filled Analyzer (AGFA) in a ²⁰³Tl(⁵⁰Ti, 2n) fusion evaporation reaction [1].

General data

Name of the isotope:Lawrencium-251; Lr-251Symbol:²⁵¹LrMass number A:251Atomic number Z:103 (= number of protons)Neutrons N:148Isotopic mass:251 u (atomic weight of Lawrencium-251)
Excitation energy: ßNuclide mass:250.943505 u (calculated nuclear mass without electrons)Mass excess:0 MeVMass defect:2.088385864 u (per nucleus)Nuclear binding energy:1945.318902 MeV (per nucleus)
7.75027451 MeV (average binding energy per nucleon)Half-life:Spin and parity:Year of discovery:2022

Radioactive Decay

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
α	²⁴⁷Md
ε ?

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 148) and isobaric (same nucleon number A = 251) with Lawrencium-251. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

OZ	Isotone N = 148	Isobar A = 251
90	²³⁸Th
91	²³⁹Pa
92	²⁴⁰U
93	²⁴¹Np
94	²⁴²Pu
95	²⁴³Am
96	²⁴⁴Cm	²⁵¹Cm
97	²⁴⁵Bk	²⁵¹Bk
98	²⁴⁶Cf	²⁵¹Cf
99	²⁴⁷Es	²⁵¹Es
100	²⁴⁸Fm	²⁵¹Fm
101	²⁴⁹Md	²⁵¹Md
102	²⁵⁰No	²⁵¹No
103	²⁵¹Lr	²⁵¹Lr