Isotopes of einsteinium

Isotopes of einsteinium (99Es)
Main isotopes[1] Decay
abun­dance half-life (t1/2) mode pro­duct
252Es synth 471.7 d α 248Bk
ε 252Cf
β− 252Fm
253Es synth 20.47 d SF –
α 249Bk
254Es synth 275.7 d ε 254Cf
β− 254Fm
α 250Bk
255Es synth 39.8 d β− 255Fm
α 251Bk
SF –

Einsteinium (99Es) is a synthetic element, and thus a standard atomic weight cannot be given. Like all synthetic elements, it has no stable isotopes. The first isotope to be discovered (in nuclear fallout from the Ivy Mike H-bomb test) was 253Es in 1952. There are 18 known radioisotopes from 240Es to 257Es, and 4 nuclear isomers. The longest-lived isotope is 252Es with a half-life of 471.7 days, or around 1.293 years.

  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.