- Es
- Es Es n.
the chemical symbol for {einsteinium}, a transuranic element
with atomic number 99. The atomic weight of the longest-lived
isotope, with a half-life of 276 days, is 254. The first
isotope discovered, having atomic weight 253 and a half-life
of 20 days, was recognized in 1952 in the debris from a
hydrogen bomb test. As much as 3 micrograms of einsteinium
were produced by a complex process involving long irradiation
of plutonium isotopes in nuclear reactors. Its chemical
properties are those of a trivalent actinide element. --HCP61
Syn: einsteinium, atomic number 99. [WordNet 1.5 +PJC]
The Collaborative International Dictionary of English. 2000.
