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.
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).
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).
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).
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.
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
|
Name |
Einsteinium
|
Symbol |
Es
|
|
Atomic
number |
99
|
Atomic
weight |
(254)
|
|
Density
@ 293 K |
?
|
Atomic
volume |
?
|
|
Group |
Rare
Earth, Actinides |
Discovered |
1954
|
|
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
|
|
Structure |
unknown |
Color |
|
|
Uses |
unknown |
Toxicity |
|
|
Hardness |
mohs
|
Characteristics |
Radioactive
|
|
Number
of isotopes |
0
|
Hydride(s) |
none |
|
Oxide(s) |
Es2O3
|
Chloride(s) |
none |
|
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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