Astatine Facts

Astatine Facts
Astatine (At) has an atomic number of eighty-five. This unstable hallogen wasn't discovered until 1940 and was once believed to be the rarest element on Earth.
Interesting Astatine Facts:
Astatine was discovered in 1940 by Dale Corson, Kenneth McKenzie, and Emilio Segre at Berkley.
It wasn't until three years later, however, that astatine was found in nature.
Since astatine is usually only found as a state of another heavier element in the process of radioactive decay, astatine is one of the rarest elements on Earth.
Only up to one gram of astatine at a time has ever been discovered in nature.
Astatine cannot be seen with the naked eye, since a large enough sample would immediately disintegrate due to its own radioactivity.
There are thirty-two isotopes of astatine.
All of them are radioactive, with the most stable being At-210, whose half-life is just over eight hours.
Only five of the isotopes even have half-lives longer than an hour.
Isotope At-211 is the only one of astatine's isotopes with a commercial use, where it is used in the diagnosis of some diseases.
Astatine is the rarest element, other than the transuranic elements (those with a higher atomic number than uranium).
Astatine was once believed to be the rarest element on Earth, prior to the discovery of berkelium in 1949; since that time less than two grams of the element have ever been produced.
Since it is only released during the radioactive decay of other elements, it is estimated that there is no more than twenty-eight grams of astatine on Earth at any time.
Astatine has an important use in nuclear medicine, but it decays so quickly that it must be used within a matter of hours following production.
Astatine concentrates in the thyroid and liver in a way similar to iodine, but it does not emit high-energy electrons like iodine does.
Its short half-life makes it preferable to iodine for some treatments.
Animal experiments show that astatine does far greater damage to cells in the thyroid than iodine does.

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