Mendelevium-256

Properties and data of the isotope ²⁵⁶Md.

Contents

General Data

Radioactive Decay

Parent Nuclides

Isotones und Isobares

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

General data

Name of the isotope:Mendelevium-256; Md-256Symbol:²⁵⁶Md or 256101MdMass number A:256 (= number of nucleons)Atomic number Z:101 (= number of protons)Neutrons N:155Isotopic mass:256.09389(13) u (atomic weight of Mendelevium-256)Nuclide mass:256.0384917 u (calculated nuclear mass without electrons)Mass excess:87.45797 MeVMass defect:2.039500212 u (per nucleus)Nuclear binding energy:1899.78221048 MeV (per nucleus)
7.42102426 MeV (average binding energy per nucleon)Separation energy:S_N = 5.46(12) MeV (first neutron)
S_P = 3.63(12) MeV (first proton)Half-life:77.7(18) minDecay constant λ:0.00014868021891033 s^-1Specific activity α:3.49755164595 × 10⁺¹⁷ Bq g^-1
9452842.2863622 Ci g^-1Spin and parity:
(nuclear angular momentum)(1-)

Radioactive Decay

Half-life T_½ = 77.7(18) min (minutes) respectively 4.662 × 10³ seconds s.

Decay mode	Daughter	Probability	Decay energy
EC	²⁵⁶Fm	90.8(7) %	1.97(12) MeV
α	²⁵²Es	9.2(7) %	7.74(11) MeV
SZ	div.	< 3 %

Parent Nuclides

Direct parent isotope is: ²⁶⁰Lr.

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 155) and isobaric (same nucleon number A = 256) with Mendelevium-256. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

Z	Isotone N = 155	Isobar A = 256
96	²⁵¹Cm
97	²⁵²Bk
98	²⁵³Cf	²⁵⁶Cf
99	²⁵⁴Es	²⁵⁶Es
100	²⁵⁵Fm	²⁵⁶Fm
101	²⁵⁶Md	²⁵⁶Md
102	²⁵⁷No	²⁵⁶No
103	²⁵⁸Lr	²⁵⁶Lr
104	²⁵⁹Rf	²⁵⁶Rf
105	²⁶⁰Db	²⁵⁶Db
106	²⁶¹Sg
107	²⁶²Bh
108	²⁶³Hs