Einsteinium

History:

       (Albert Einstein) Einsteinium, the seventh transuranic element of the actinide series to be discovered, was identified by Ghiorso and co-workers at Berkeley in December 1952 in debris from the first large thermonuclear explosion, which took place in the Pacific in November, 1952. The isotope produced was the 20-day 253Es isotope. In 1961, a sufficient amount of einsteinium was produced to permit separation of a macroscopic amount of 253Es. This sample weighted about 0.01Mg. A special magnetic-type balance was used in making this determination. 253Es so produced was used to produce mendelevium (Element 101). About 3Mg of einsteinium has been produced at Oak Ridge National Laboratories by irradiating for several years kilogram quantities of 239Pu in a reactor to produce 242Pu. This was then fabricated into pellets of plutonium oxide and aluminum powder, and loaded into target rods for an initial 1-year irradiation at the Savannah River Plant, followed by irradiation in a HFIR (High Flux Isotopic Reactor). After 4 months in the HFIR the targets were removed for chemical separation of the einsteinium from californium. Fourteen isotopes of einsteinium are now recognized. 254Es has the longest half-life (275 days). Tracer studies using 253Es show that einsteinium has chemical properties typical of a heavy trivalent, actinide element.

Reactions:

 

Reaction of einsteinium with air

As only a little einsteinium ever been made, its reactivity with air is unknown. One would predict its behaviour to be similar to that of holmium (immediately above einsteinium in the periodic table).

Reaction of einsteinium with water

As only a little (a few milligrammes) einsteinium ever been made, its reactivity with water is largely unknown. There are one or two comments in the literature to the effect that einsteinium does react with water or steam, probably to form einsteinium(III) oxide, Es2O3, and maybe other products as well. I'm not sure whether these comments are a prediction or based upon actual experiment. One would predict its behaviour to be similar to that of erbium (immediately above fermium in the periodic table).

Reaction of einsteinium with the halogens

As only a little einsteinium ever been made, its reactivity with the halogens is unknown. One would predict its behaviour to be similar to that of holmium (immediately above einsteinium in the periodic table).

Reaction of einsteinium with acids

As only a little einsteinium ever been made, its reactivity with acids is largely unknown. One would predict its behaviour to be similar to that of holmium (immediately above einsteinium in the periodic table). There are one or two comments in the literature to the effect that einsteinium does react with some acids. I'm not sure whether these comments are a prediction or based upon actual experiment.

Reaction of einsteinium with bases

As only a little einsteinium ever been made, its reactivity with bases is largely unknown. One would predict its behaviour to be similar to that of holmium (immediately above einsteinium in the periodic table). There are one or two comments in the literature to the effect that einsteinium does not react with alkalis. I'm not sure whether these comments are a prediction or based upon actual experiment

 

 

General

Name

Einsteinium

Symbol

Es

Atomic number

99

Atomic weight

(254)

Density @ 293 K

?

Atomic volume

?

Group

Rare Earth, Actinides

Discovered

1954

Oxidation & Electrons

Shells

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

Electron configuration

[Rn] 5f11 7s2

Minimum oxidation number

0

Maximum oxidation number

3

Minimum common oxidation number

0

Maximum common oxidation number

3

Appearance & Characteristics

Structure

 unknown

Color

 

Uses

 unknown

Toxicity

 

Hardness

mohs

Characteristics

Radioactive

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Other Forms

Number of isotopes

0

Hydride(s)

 none

Oxide(s)

Es2O3

Chloride(s)

 none

Radius

Ionic radius (2- ion)

pm

Ionic radius (1- ion)

pm

Atomic radius

186 pm

Ionic radius (1+ ion)

pm

Ionic radius (2+ ion)

pm

Ionic radius (3+ ion)

pm

 

 

 

 

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