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Einsteinium (Es): Fun Facts and Information About the Element

What is the symbol? Es
What is the atomic number? 99
What is the atomic weight? 252
What is the melting point in Celsius? 860
What year was it discovered? 1952
Who discovered the element? Albert Ghiorso et. al.
What group is the element in? 102
What is the ionization energy? 6.42
What element category is it in? Actinoids

Where is Einsteinium Found?

About 3Mg of einsteinium has been produced at Oak Ridge National Laboratories by taking the following steps:

1. Irradiating kilogram quantities of 239Pu in a reactor for several years to produce 242Pu
2. Fabricating the 242Pu into pellets of plutonium oxide and aluminum powder
3. Loading the pellets into target rods for an initial 1-year irradiation
4. Irradiating the targets for another 4 months in a HFIR.
5. The targets are removed for chemical separation of the einsteinium from californium.