Which element is named after Albert Einstein?

Einsteinium is the element named after physicist Albert Einstein.

Einsteinium has the symbol Es and atomic number 99. It is a synthetic actinide, meaning it does not occur naturally on Earth in lasting quantities and must be produced in nuclear reactions. Scientists first identified it in debris from the Ivy Mike thermonuclear test at Enewetak Atoll on November 1, 1952.

The Berkeley team led by Albert Ghiorso proposed the name einsteinium, alongside fermium for element 100, honoring Enrico Fermi. The names were announced publicly in 1955 after the discovery results had been declassified. Einstein and Fermi had both died by the time the names became official.

Einsteinium is extremely difficult to study because only tiny amounts can be made and its isotopes are highly radioactive. Its most common isotope, einsteinium-253, has a half-life of about 20.5 days. Researchers nevertheless used einsteinium to create the first atoms of mendelevium in 1955.