Atomic number: 99

Symbol: Es

Category: actinide 

Density at 25°C: solid: density: 8.84 g·cm−3

Einsteinium is a highly radioactive element that only exists briefly as a result of intense bombardment by other elements and neutrons. In other words it is synthetically produced on Earth. It was originally discovered in radioactive debris from the testing a hydrogen bomb explosion. 


Nuclear test Ivy Mike. image: wikipedia

Einsteinium was first identified in December 1952 by Albert Ghiorso and co-workers at the University of California, Berkeley in collaboration with the Argonne and Los Alamos National Laboratories, in the fallout from the Ivy Mike nuclear test.

Use, natural applications or common combinations: 

  • only useful for scientific research in producing heavier elements
  • Heaviest element that has been seen in macroscopic amounts.

Basic characteristics:

  • Standard atomic weight: (252)
  • Melting point:  860 °C
  • Boiling point:  unknown
  • Radioactivity: all radioactive
    • 254Es with half life of 275.7 days decays via beta, alpha and electron capture
    • 252Es with half life of 471 days decays via alpha, beta and electron capture.