Nobelium-254

Properties and data of the isotope ²⁵⁴No.

Contents

General data

Name of the isotope:Nobelium-254; No-254Symbol:²⁵⁴No or 254102NoMass 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-254)Nuclide 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)Separation energy:S_N = 7.707(12) MeV (first neutron)
S_P = 3.74(3) MeV (first proton)Half-life:51.2(4) sDecay constant λ:0.013538030870311 s^-1Specific activity α:3.209760979023 × 10⁺¹⁹ Bq g^-1
867502967.30354 Ci g^-1Spin and parity:
(nuclear angular momentum)0+Year of discovery:1966

Radioactive Decay

Half-life T_½ = 51.2(4) s respectively 5.12 × 10¹ seconds s.

Decay mode	Daughter	Probability	Decay energy
EE	²⁵⁴Md	10(1) %	1.27(10) MeV
α	²⁵⁰Fm	90(1) %	8.226(8) MeV
SZ	div.	0.17(2) %

Parent Nuclides

Direct parent isotope is: ²⁵⁸Rf.

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
^254mNo	1296.4(11) keV	265(2) ms	(8-)

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-254. 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