<P> Astatine is a radioactive chemical element with symbol At and atomic number 85 . It is the rarest naturally occurring element in the Earth 's crust , occurring only as the decay product of various heavier elements . All of astatine 's isotopes are short - lived ; the most stable is astatine - 210 , with a half - life of 8.1 hours . A sample of the pure element has never been assembled , because any macroscopic specimen would be immediately vaporized by the heat of its own radioactivity . </P>
<P> Astatine is a radioactive chemical element with symbol At and atomic number 85 . It is the rarest naturally occurring element in the Earth 's crust , occurring only as the decay product of various heavier elements . All of astatine 's isotopes are short - lived ; the most stable is astatine - 210 , with a half - life of 8.1 hours . A sample of the pure element has never been assembled , because any macroscopic specimen would be immediately vaporized by the heat of its own radioactivity . </P>
what is the most rarest element on earth
what is the most rarest element on earth
Astatine
Astatine