99
252.00

Es

Einsteinium

Identification

CAS Number: 7429-92-7
Discovery Year: 1952
Discoverer: Argonne, Los Alamos, U of Calif
Discovery Location: United States

Atomic Dimensions

Van der Waals Radius: 245.00000000000003 pm

Thermodynamics

Boiling Point: 1130 K
Heat of Formation: 133 kJ/mol

Electronic Structure

Electron Config: [Rn] 5f11 7s2
Block: f
Period: 7
Oxidation States: +3

Abundance & Geochemistry

Goldschmidt Class: synthetic

About

Appearance is unknown, however it is most probably metallic and silver or gray in color. Radioactive metallic transuranic element belonging to the actinoids. Es-254 has the longest half-life of the eleven known isotopes at 270 days. First identified by Albert Ghiorso and associates in the debris of the 1952 hydrogen bomb explosion. In 1961 the first microgram quantities of Es-232 were separated. While einsteinium never exists naturally, if a sufficient amount was assembled, it would pose a radiation hazard.

Isotopes

Es-252 252 472 d
Es-254 254 276 d