Einsteinium (Es)


  • Symbol: Es
  • Atomic Number: 99
  • Atomic Weight: [252]
  • Element Classification: Actinide
  • Discovered By: Albert Ghiorso and the Lawrence Berkeley National Laboratory team
  • Discovery Date: 1952
  • Name Origin: Named after Albert Einstein
  • Density(g/cc): 8.84 (estimated)
  • Melting Point: 860°C (estimated)
  • Boiling Point: Not determined
  • Appearance: Silver-colored, radioactive metal (appearance is theoretical due to its extreme radioactivity and rarity)
  • Atomic Radius(pm): 186 (estimated)


Einsteinium was discovered by Albert Ghiorso and the research team at the Lawrence Berkeley National Laboratory in December 1952. It was identified in the debris of the first hydrogen bomb test, conducted in the Pacific Ocean at the Enewetak Atoll as part of Operation Ivy. The discovery of einsteinium, alongside fermium, was a byproduct of the thermonuclear explosion, which produced a large number of heavy elements. Einsteinium was named in honor of Albert Einstein, reflecting his monumental contributions to physics.

Relation to Other Elements

Einsteinium is a member of the actinide series, sharing common features with these elements, such as radioactivity and the ability to form multiple oxidation states. Like other late actinides, einsteinium primarily exhibits a +3 oxidation state in its compounds. Its chemical and physical properties are not well-characterized due to its scarcity, high radioactivity, and short half-life of its most stable isotope, einsteinium-252, which has a half-life of about 471.7 days.

Natural Occurrence

Einsteinium does not occur naturally on Earth and is produced synthetically in very small amounts through nuclear reactors or particle accelerators. It is typically synthesized by bombarding heavy actinide targets, such as curium or plutonium, with neutrons or light ions.


Due to its extreme radioactivity and the difficulty in producing significant quantities, einsteinium’s uses are confined to scientific research:

  • Scientific Research: The primary use of einsteinium is in basic scientific studies to understand the properties of actinide elements. Research with einsteinium has contributed to a greater understanding of the synthesis of heavy elements and their nuclear and chemical behavior.
  • Production of Heavier Elements: Einsteinium has been used as a target material in particle accelerators to synthesize heavier elements, such as mendelevium and others, by bombarding it with charged particles.

The discovery of einsteinium expanded the periodic table and contributed to the development of nuclear science, particularly in the study of transuranium elements and their synthesis. While its practical applications are limited, einsteinium plays an important role in advancing fundamental scientific knowledge.

Californium (Cf)

Fermium (Fm)