Einsteinium

1 · Identity

Symbol, number

Es, 99

Oxidation states in water

+3 (book entry); never measured in natural water

Note

Identity from the book entry; nothing measured in water.

Sources

Identity

Name and symbol

Einsteinium, Es

Atomic number

99 protons

Position

no group (f-block) · period 7 · f-block · actinide

CAS number

7429-92-7

Atomic structure

Atomic mass

252 u

Electron configuration

1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁶ 6s² 4f¹⁴ 5d¹⁰ 6p⁶ 7s² 5f¹¹
[Rn] 7s²⁵f¹¹

Electrons per shell

2, 8, 18, 32, 29, 8, 2

Valence electrons

13 ns, (n-1)d and (n-2)f

Physical properties

State at room temperature

Solid

Melting point

1,133 K (859.85 °C)

Boiling point

996 K (722.85 °C)

Density

not in sources

Appearance

silvery; glows blue in the dark

Thermal conductivity

not in sources

Electrical resistivity

not in sources

Electrical conductivity

not in sources

Crystal structure

face-centered cubic

Molar heat capacity

not in sources

Chemical properties

Oxidation states

+3

Electronegativity

1.3 (Pauling Scale)

Ionisation energy

6.42 eV
1st 619 kJ/mol

Electron affinity

not in sources

Atomic radius

van der Waals 245 pm

Ionic radius

Es³⁺ 84 pm

Reactivity

A soft, silvery, rather reactive late actinide and the heaviest element studied in bulk: +3 dominates in solids and in solution (pale pink), and it is the first actinide in which a +2 state is firmly established, made by reducing Es(III) with samarium(II) chloride.

with water

The sources do not describe the metal with water; Es3+ is the stable aqueous ion and the trihalides react with water vapor to oxyhalides such as EsOCl.

with oxygen, air

The sources do not describe the metal with oxygen; the oxide Es2O3 was obtained by burning the nitrate and exists in cubic, monoclinic and hexagonal forms that interconvert under self-irradiation.

with acids

Tracer studies show trivalent actinide behavior in acid solution, giving the pale pink Es3+ ion whose luminescence has been observed in hydrochloric acid.

with halogens

No reaction of the metal with the halogens is reported; the trihalides EsF3, EsCl3, EsBr3 and EsI3 are made from the oxide or from solution, and hydrogen reduces them to the dihalides: $\ce{2 EsCl3 + H2 -> 2 EsCl2 + 2 HCl}$.

Typical compounds

• Es₂O₃ einsteinium(III) oxide colorless cubic crystals, from burning the nitrate
• EsF₃ einsteinium(III) fluoride precipitated from Es(III) chloride solution with fluoride
• EsCl₃ einsteinium(III) chloride orange, from the oxide in dry hydrogen chloride
• EsCl₂ einsteinium(II) chloride divalent, from hydrogen reduction of the trichloride

Occurrence, production and use

Crustal abundance

Not Applicable

Oceanic abundance

Not Applicable

Occurrence and sources

• synthetic only milligram quantities from neutron bombardment of plutonium in a reactor

Extraction, production

not in sources

Uses

Since only small amounts of einsteinium have ever been produced, it currently has no uses outside of basic scientific research.

Safety, toxicity

not in sources

Discovery and name

Discovered by

Lawrence Berkeley National Laboratory

Discovered

1952

First isolated

not in sources

Named by

not in sources

Origin of the name

after Albert Einstein

Einsteinium does not occur naturally in the Earth’s crust. It was first identified in December 1952 by American scientists from the Argonne National Laboratory near Chicago, Illinois, the Los Alamos National Laboratory in Los Alamos, New Mexico, and The University of California Laboratory in Berkeley, California in the debris of thermonuclear weapons. The element was named for Albert Einstein (Fig. IUPAC.99.1). 253Es was the first isotope identified; it has a half-life of 20.47 days. The isotope with the longest half-life is 252Es, with a half-life of 472 days [630], [631].

There are no uses for isotopes of einsteinium outside of basic scientific research for the production of higher transuranic elements and studies of actinide science. Due to the radiation and heat given off by einsteinium isotopes, it is difficult to use them in experiments and studies [631].

Tracer studies using 253Es show that einsteinium has chemical properties typical of a heavy trivalent, actinide element. Oxidation states of II and III for einsteinium have been reported and oxidation state IV has been postulated from vapor transport studies but not established unequivocally. Einsteinium is the first divalent metal in the actinide series (two bonding electrons rather than three). The self-irradiation properties of einsteinium make it extremely difficult, for example, to obtain x-ray crystallographic data. The intense gamma and x-rays from einsteinium decay to daughter products over-exposes the x-ray film/detector. This intense self-irradiation can be exploited however to study accelerated aging and radiation damage studies, and for targeted radiation medical treatments. An example of einsteinium chemical studies is the chemical consequences of radioactive decay. With the relatively short half-life of Es-253 (20.47 days) one can study the in-growth of daughter Bk-249 (half-life 330 days) and grand-daughter Cf-249 (half-life 351 years). Evidence suggests that divalent Es might decay into a divalent Bk daughter and subsequently into as of yet unknown divalent Cf. There are no commercial uses for einsteinium however it is the heaviest element for which bulk studies can be performed that allows for fundamental studies of the role of 5-f electrons in actinide systematics.

Further reading:

Richard G. Haire (2006) Chapter 12, The Chemistry of the Actinide and Transactinide Elements, Third Edition, L. R. Morss, J. Fuger, and N. M. Edelstein, Eds, Springer Publishers.

This element reviewed and Updated by Dr. David Hobart, 2011