Astatine (atomic number 85, symbol At) is a radioactive metal, first produced by Emilio Segre, Kenneth Ross MacKenzie, and Dale Corson in 1940. In nature, it is formed by radioactive decay and exists in small amounts because of its short half-life. This element is, in fact, the rarest one to occur naturally, with estimates that no more than thirty grams are found in the earth's crust. Astatine is the heaviest halogen, known to men. It is believed that the metal accumulates in the thyroid gland similar to iodine.
Astatine has 20 known isotopes and all of them are radioactive. Other...Read More