Properties

Atomic Number	99
CAS Registry Number	7429-92-7
Chemical Symbol	Es

History

The atomic number is 99 and the chemical symbol is Es. The name derives from Albert Einstein the Geituan born physicist who proposed the theory of relativity. A collaboration of American scientists from the Argonne National Laboratory near Chicago Illinois the Los Alamos Scientific Laboratory in Los Alamos New Mexico and at the University of California lab in Berkeley California first found 252Es in the debris of thermonuclear weapons in 1952. The longest half-life associated with this unstable element is 472 day 252Es.

Holden, Norman E., (2004). History of the origin of the chemical elements and their discoverers. National Nuclear Data Center. Retrieved from http://www.nndc.bnl.gov/content/elements.html