The chemical element of atomic number 99, a radioactive metal of the actinide series. Einsteinium does not occur naturally and was discovered in 1953 in debris from the first hydrogen bomb explosion.
- ‘They were named after two of the century's most creative physicists: einsteinium and fermium.’
- ‘All isotopes of einsteinium are radioactive, the most stable being einsteinium - 252 with a half life of 20.47 days.’
- ‘Atomic number 101 is a radioactive transuranic element synthesized by bombarding einsteinium with alpha particles.’
- ‘A tiny sample of einsteinium - 253 was bombarded with alpha particles in the university's 60-inch cyclotron.’
- ‘I don't know how Albert would have felt about this, but the element was named einsteinium, in his honor.’
1950s: from the name of Albert Einstein, Albert + -ium.