Astatine: The Rarest Natural Element on Earth

Astatine (At) is a fascinating element that holds the title of the rarest naturally occurring element on Earth. It's so rare, there's just 30 grams TOTAL in Earth's crust.

The rarest naturally occurring element on Earth is astatine, with an atomic number of 85 and symbol At.

Named after the Greek word for unstable (astatos), Astatine is a naturally occurring semi-metal that results from the decay of uranium and thorium. In its most stable form - astatine-210 - it's got a half-life of just 8.1 hours, which means even if you did happen to stumble on some of it, half of it would be gone by the end of a work day. Depending on how it decays, it'll either turn into the isotopes bismuth-206 or polonium-210.

The Rarest Natural Element on Earth. This mineral, Autunite, appears in my Photographic Periodic Table Poster representing astatine, because this highly unstable element can't reasonably be photographed.

This instability, combined with its actual scarceness, means that at any one time, there's less than 30 grams of it in the Earth's crust. If scientists need to use it, they have to produce it from scratch, that said, only 0.05 micrograms (0.00000005 grams) of astatine have been produced to date. No one's ever seen it in its elemental state, because if you had enough of it to see it with the naked eye, it would have already been vaporised by the heat of its own radioactivity.That said, scientists assume it would take on a dark or metallic appearance if you could see it.

The Rarest Natural Element on Earth

Astatine Occurrence:

  • Astatine does not exist in significant amounts on Earth. It is primarily produced as a decay product of heavier elements like uranium and thorium.
  • Due to its short half-life (the shortest of any naturally occurring element), any astatine that is formed quickly decays back into other elements.

Astatine Properties:

  • Astatine is a radioactive metallic element.
  • It exists in 34 known isotopes, all of which are radioactive.
  • Its most stable isotope, astatine-210, has a half-life of 8.1 hours.
  • The chemical properties of astatine are similar to those of other halogens, such as chlorine and iodine.

Astatine Interesting facts:

  • Astatine was first discovered in 1940 by Dale Corson, Kenneth MacKenzie, and Emilio Segrè at the University of California, Berkeley.
  • The name "astatine" comes from the Greek word "astatos," meaning "unstable," which reflects the element's short half-life.
  • Astatine is the only element discovered in the United States.

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