Naturally occurring radioactive elements are substances whose atomic nuclei are unstable. To become stable, these nuclei spontaneously break down, or decay, by releasing energy in the form of ...

Since element 99 -- einsteinium -- was discovered in 1952 from the debris of the first hydrogen bomb, scientists have performed very few experiments with it because it is so hard to create and is ...

Element 99 — mysterious and exceptionally radioactive — sits inconspicuously in the bottom row of the periodic table. Named for legendary physicist Albert Einstein, einsteinium has been one of the ...