Isotopes of mendelevium

Isotopes of mendelevium (101Md)
Main isotopes[1] Decay
abun­dance half-life (t1/2) mode pro­duct
256Md synth 77.7 min ε 256Fm
α 252Es
257Md synth 5.52 h ε 257Fm
α 253Es
SF
258Md synth 51.5 d α 254Es
ε 258Fm
β 258No
259Md synth 1.60 h SF
α 255Es
260Md synth 31.8 d SF
α 256Es
ε 260Fm
β 260No

Mendelevium (101Md) is a synthetic element, and thus a standard atomic weight cannot be given. Like all artificial elements, it has no stable isotopes. The first isotope to be synthesized was 256Md (which was also the first isotope of any element produced one atom at a time) in 1955. There are 17 known radioisotopes, ranging in atomic mass from 244Md to 260Md, and 5 isomers. The longest-lived isotope is 258Md with a half-life of 51.3 days, and the longest-lived isomer is 258mMd with a half-life of 57 minutes.

  1. ^ Kondev, F. G.; Wang, M.; Huang, W. J.; Naimi, S.; Audi, G. (2021). "The NUBASE2020 evaluation of nuclear properties" (PDF). Chinese Physics C. 45 (3): 030001. doi:10.1088/1674-1137/abddae.