Nobelium-254m

Properties and data of the isotope ^254mNo.

Contents

General data

Name of the isotope:Nobelium-254m; No-254mSymbol:^254mNo or 254m102NoMass number A:254 (= number of nucleons)Atomic number Z:102 (= number of protons)Neutrons N:152Isotopic mass:254.090954(10) u (atomic weight of Nobelium-254m)
Excitation energy: 1296.4(11) keVNuclide mass:254.0350073 u (calculated nuclear mass without electrons)Mass excess:84.72311 MeVMass defect:2.024266496 u (per nucleus)Nuclear binding energy:1885.59209543 MeV (per nucleus)
7.42359093 MeV (average binding energy per nucleon)Half-life:265(2) msDecay constant λ:2.6156497379621 s^-1Specific activity α:6.201500457584 × 10⁺²¹ Bq g^-1
167608120475.25 Ci g^-1Spin and parity:
(nuclear angular momentum)(8-)

Radioactive Decay

Half-life T_½ = 265(2) ms respectively 2.65 × 10^-1 seconds s.

Decay mode	Daughter	Probability
Iso	²⁵⁴No	ca. 100 %
SZ	div.	0.020(12) %
α	²⁵⁰Fm	≤ 0.01 %

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
²⁵⁴No		51.2(4) s	0+

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 152) and isobaric (same nucleon number A = 254) with Nobelium-254m. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

Z	Isotone N = 152	Isobar A = 254
94	²⁴⁶Pu
95	²⁴⁷Am
96	²⁴⁸Cm
97	²⁴⁹Bk	²⁵⁴Bk
98	²⁵⁰Cf	²⁵⁴Cf
99	²⁵¹Es	²⁵⁴Es
100	²⁵²Fm	²⁵⁴Fm
101	²⁵³Md	²⁵⁴Md
102	²⁵⁴No	²⁵⁴No
103	²⁵⁵Lr	²⁵⁴Lr
104	²⁵⁶Rf	²⁵⁴Rf
105	²⁵⁷Db
106	²⁵⁸Sg