Einsteinium Element

Einsteinium is a synthetic element with the atomic number 99 and is a part of the periodic table. It is represented by the symbol "Es" in the periodic table. It is also a member of the actinide series. Einsteinium is the seventh transuranic element and falls in category 13 of the heavy transuranic subsets of the elements.

Einsteinium is synthetic, i.e. it does not occur in nature, nor is it present on the surface of the earth. It is formed in limited quantities by artificial natural transmutations of certain radioactive elements or by a further explosion of thermonuclear bombs.

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Who Discovered Einsteinium?

The initial discovery of Einsteinium (element 99) was an unforeseen result of the detonation of the first thermonuclear weapon, "Mike," which took place on 1 November 1952. 

In December 1952, Einsteinium, the seventh transuranic atom in the actinide sequence to be found, was detected by Ghiorso and his co-workers at Berkeley in rubble from the first large thermonuclear blast in the Pacific. Einsteinium was identified as a trace ingredient in the debris from the huge explosion of the Eniwetok hydrogen bomb.

The findings of many of the trans-uranium elements were the result of meticulous theoretical preparation, taking into consideration laboratory methods, forecasts of chemical and nuclear properties.

Einsteinium was one of the trace elements that had been identified. Initial investigations had also revealed fermium and other new elements. Its presence, as well as the presence of many other discovered elements, was not revealed until 1955 owing to the secrecy of this new form of a thermonuclear weapon.

Einsteinium is created by a series of nuclear reactions that includes bombing each isotope and then enabling beta-decay isotopes.

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Naming of Einsteinium

The second element was named in Albert Einstein's honour. The symbol initially introduced for Einsteinium was E, but when IUPAC accepted the name in 1957, they modified the symbol to Es in order to conform to their current regulation that all newly identified elements would have two-letter symbols.

Einsteinium Atomic Number

The atomic number basically defines the number of protons in the particular element. An element is identified by the number of protons, which is given by the atomic number. 

The atomic number of the element Einsteinium is 99.

Einsteinium Electron Configuration

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An atom has various shells on which electrons revolve around the nucleus. The number of electrons present in each of the shells is known as the electronic configuration of an element.

The electronic configuration of Einsteinium is [Rn] 5f117s2.  In a simpler form, the electrons per shell of Einsteinium can be written as [2, 8, 18, 32, 29, 8, 2]. Einsteinium can have a valency of +2, +3, and +4.

Einsteinium Atomic Mass

The atomic mass of an element refers to the mass of one atom of that element, which is measured in atomic mass units (u), where one atomic mass unit is equivalent to 1/12 the mass of carbon-12 isotope. When calculating the atomic mass of a particular element, we add up the mass of the protons and neutrons, because the mass of the electrons is negligible compared to their mass. 

The atomic mass for Einsteinium is 252, but it can vary depending on the isotope. 

Isotopes of Einsteinium

Einsteinium is a radioactive metallic element and a member of the periodic table group of actinides. It reacts with the oxygen atom, steam, and acids, but it does not react with alkali. The desired oxidation level for the einsteinium atom is +3. 

Isotopes are forms of an element with the same atomic numbers but different mass numbers, i.e. a different number of neutrons. Isomers are forms of a compound or radical that contain the same number of atoms of the same elements but vary in structural arrangement and other characteristics.

There are 17 known Einsteinium isotopes with mass numbers from 241 to 257 and 3 identified isomers. All Einsteinium isotopes are radioactive, and the isotope Einsteinium-252 with a half-life of 472 days is the one with the longest lifespan. 

Properties of Einsteinium



Melting point

860°C, 1580°F, 1133 K



Boiling point




Density (g cm−3)


Atomic number


Relative atomic mass


State at 20°C


Key isotopes


Electron configuration

[Rn] 5f117s2

CAS number



Uses of Einsteinium

    1. Only small quantities of Einsteinium have ever been produced, and this is mainly used in scientific studies. 

    2. One can simulate and study radioactive decay through Einsteinium. 

    3. It is among the heaviest elements on which we can perform bulk studies. 

    4. It has some medical uses but is not yet commercial.  

    5. It is mainly used for studying radiation damage, targeted medical radiation treatments and accelerated ageing.

FAQ (Frequently Asked Questions)

1. Why are the Applications of Einsteinium Limited?

It is of no practical value because only a few of its compounds are considered to have a half-life of about 20 days (which is why it will not be worth producing a drug or substance with this element). Also, because only a limited amount of Einsteinium has been made, it is generally not used outside of basic scientific research. The isotope Es-253 is used to make an element known as mendelevium. In particular, in 1955, Einsteinium was used for the first time to synthesise 17 atoms of the new element mendelevium. Due to these factors, its application is restricted to academic purposes only.

2. Have any Studies Been Done Regarding the Toxicity of Einsteinium in Living Beings?

The data available regarding the toxicity of Einsteinium is largely based on the research done on animals. In the research, Einsteinium has been found to have toxic effects on the subjects. When rates were made to ingest Einsteinium, only 0.01% of it ended in the bloodstream. Almost 65% went to the bones where it remains for almost 50 years, 25% of einsteinium ends up in the lungs, miniscule quantities reach the reproductive organs. The remaining 10% of ingested einsteinium is excreted.