Mendelevium-258m

Properties and data of the isotope ^258mMd.

Contents

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

General data

Name of the isotope:Mendelevium-258m; Md-258mSymbol:^258mMd or 258m101MdMass number A:258 (= number of nucleons)Atomic number Z:101 (= number of protons)Neutrons N:157Isotopic mass:258.098430(5) u (atomic weight of Mendelevium-258m)
Excitation energy: +x keVNuclide mass:258.0430317 u (calculated nuclear mass without electrons)Mass excess:91.68695 MeVMass defect:2.052290044 u (per nucleus)Nuclear binding energy:1911.69586225 MeV (per nucleus)
7.40967388 MeV (average binding energy per nucleon)Half-life:57.0(9) minDecay constant λ:0.00020267461419881 s^-1Specific activity α:4.730756106351 × 10⁺¹⁷ Bq g^-1
12785827.314462 Ci g^-1Spin and parity:
(nuclear angular momentum)(1-)

Radioactive Decay

Half-life T_½ = 57.0(9) min (minutes) respectively 3.420 × 10³ seconds s.

Decay mode	Daughter	Probability	Decay energy
EC	²⁵⁸Fm	70 %	1.26(20) MeV
β^-	²⁵⁸No	10 %	0.210(100) MeV
SZ, β^-	div	20 %
α	²⁵⁴Es	< 1.2 %	7,2713(19) MeV

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
²⁵⁸Md		51.50(29) d	(8-)

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 157) and isobaric (same nucleon number A = 258) with Mendelevium-258m. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

Z	Isotone N = 157	Isobar A = 258
97	²⁵⁴Bk
98	²⁵⁵Cf
99	²⁵⁶Es
100	²⁵⁷Fm	²⁵⁸Fm
101	²⁵⁸Md	²⁵⁸Md
102	²⁵⁹No	²⁵⁸No
103	²⁶⁰Lr	²⁵⁸Lr
104	²⁶¹Rf	²⁵⁸Rf
105	²⁶²Db	²⁵⁸Db
106	²⁶³Sg	²⁵⁸Sg
107	²⁶⁴Bh
108	²⁶⁵Hs
109	²⁶⁶Mt
110	²⁶⁷Ds