Source:http://linkedlifedata.com/resource/umls/id/C0013741
MSH: Einsteinium. A man-made radioactive actinide with atomic symbol Es, atomic number 99, and atomic weight 252. Its known isotopes range in mass number from 243-246. Its valence can be +2 or +3. Einsteinium was originally discovered in the debris from a thermonuclear explosion in 1952.