Einsteinium belongs to the actinoids, and it is the 7th of them. The most stable isotope of Einsteinium has 99 protons and electrons and 153 neutrons. There are 19 different (radioactive) isotopes. Einsteinium is named after Albert Einstein. It was found for the first time in 1952 by Albert Ghiorso and his team of scientists in the debree of the first hydrogen bomb explosion, and identified as an element at the University of California, Berkeley.
Einsteinium isotopes have a half-life between 40 and 471 days. Einsteinium has been used to create the element Mendelevium for the first time, in 1955, although no practical uses are known.