Einsteinium Element Facts

The chemical element einsteinium is classed as an actinide metal. It was discovered in 1952 by a project led by Albert Ghiorso.


Quartz vial glowing from the intense alpha radiation emitted by 300 micrograms of einsteinium-253. Photo by R. G Haire.


Data Zone

Classification: Einsteinium is an actinide metal
Atomic weight: (252), no stable isotopes
State: solid
Melting point: 860 oC, 1133 K
Boiling point:
Electrons: 99
Protons: 99
Neutrons in most abundant isotope: 153
Electron shells: 2,8,18,32,29,8,2
Electron configuration: [Rn] 5f11 7s2
Density @ 20oC: 8.84 g/cm3
Show more, including: Heats, Energies, Oxidation, Reactions, Compounds, Radii, Conductivities
Atomic volume: 28.5 cm3/mol
Structure: close packed cubic
Specific heat capacity
Heat of fusion
Heat of atomization
Heat of vaporization
1st ionization energy 619 kJ mol-1
2nd ionization energy
3rd ionization energy
Electron affinity
Minimum oxidation number 0
Min. common oxidation no. 0
Maximum oxidation number 3
Max. common oxidation no. 3
Electronegativity (Pauling Scale) 1.3
Polarizability volume 19.7 Å3
Reaction with air
Reaction with 15 M HNO3
Reaction with 6 M HCl
Reaction with 6 M NaOH
Oxide(s) Es2O3
Chloride(s) EsCl3
Atomic radius 186 pm
Ionic radius (1+ ion)
Ionic radius (2+ ion)
Ionic radius (3+ ion)
Ionic radius (1- ion)
Ionic radius (2- ion)
Ionic radius (3- ion)
Thermal conductivity
Electrical conductivity
Freezing/Melting point: 860 oC, 1133 K

Einsteinium Radioactive

Einsteinium is a radioactive element.

Discovery of Einsteinium

Dr. Doug Stewart

Einsteinium was the seventh synthetic transuranium element of the actinide series to be discovered.

Einsteinium-253 (half-life 20.47 days) was identified in 1952 by teams of scientists from the Lawrence Berkeley National Laboratory, the Argonne National Laboratory and the Los Alamos Scientific Laboratory. The project was led by Albert Ghiorso.

Einsteinium was discovered unexpectedly along with fermium in debris from the first large hydrogen bomb test, which took place in the Pacific on October 31 1952. The debris was collected on filter papers attached to drone airplanes that flew through the explosion area. Later, to obtain more material, many hundreds of pounds of coral from the blast area were examined. Einsteinium was identified by chemical analysis. (1)

The new element was produced by the nuclear explosion in miniscule amounts by the addition of 15 neutrons to uranium-238 (which then underwent seven beta decays). (2)

In 1961 einsteinium was produced in a weighable quantity (0.01 micrograms) for the first time. (3)

The pure metal was isolated for the first time in the 1970s. (3a)

The element is named after Albert Einstein.

Transuranium elements discovery and experiments. 1963 chemistry educational documentary narrated by Glenn Seaborg, Stanley Thompson and Albert Ghiorso.

Appearance and Characteristics

Harmful effects:

Einsteinium is harmful due to its radioactivity.


Einsteinium is a synthetic, highly radioactive metal that has only been produced in tiny amounts.

It is the first divalent metal in the actinide series (two bonding electrons rather than three). (3b)

Uses of Einsteinium

Einsteinium is of research interest only.

In 1955 einsteinium-253 was used to create mendelevium for the first time. Less than a picogram of einsteinium-253 was bombarded with alpha particles in Berkeley’s 150-centimeter cyclotron. (4)

Abundance and Isotopes

Abundance earth’s crust: nil

Abundance solar system:

Cost, pure: $ per g

Cost, bulk: per 100g

Source: Einsteinium is a synthetic element and is not found naturally. It is produced in nuclear reactors in miniscule amounts from the neutron bombardment of plutonium. Up to 2 mg can be produced from the High Flux Isotope Reactor (HFIR) at Oak Ridge National Laboratory. (4)

Isotopes: Einsteinium has 16 isotopes whose half-lives are known, with mass numbers 241 to 256. Einsteinium has no naturally occurring isotopes. Its longest lived isotopes are 252Es, with a half-life of 471.7 days, 254Es with a half-life of 257.7 days and 255Es with a half-life of 39.8 days.


1. Glenn T. Seaborg, The Transcalifornium Elements., Journal of Chemical Education, Vol 36.1 (1959) p39.
2. Robert E. Krebs, The history and use of our earth’s chemical elements: a reference guide., Greenwood Publishing Group, 2006., p329.
3. Richard G. Haire, The Chemistry of the Actinide and Transactinide Elements., Springer., Vol 3.12, p1577-1578.
3a. Richard G. Haire, The Chemistry of the Actinide and Transactinide Elements., Springer., Vol 3.12, p1584.
3b. Richard G. Haire, The Chemistry of the Actinide and Transactinide Elements., Springer., Vol 3.12, p1579.
4. Jack M. Holl, Richard G. Hewlett, Ruth R. Harris., Argonne National Laboratory, 1946-96., University of Illinois Press, 1997., page 179.

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