Astatine is a semimetallic chemical element classified among the halogens in the periodic table of elements. It is radioactive and extremely unstable, with a half-life of around eight hours. As a result of its instability, this element is incredibly rare; naturally, around 1 ounce (28 grams) of this element exists at any given time, making it the rarest naturally occurring element. It is also possible to create this element and several of its isotopes in a laboratory setting by bombarding bismuth with alpha particles.
Because astatine is so rare, it does not have any commercial uses. Consumers probably never interact with it, although scientists often do. Like other elements, it has been the subject of extensive research in lab settings because scientists are interested in learning more about all of the substances that can be found on Earth. Some researchers suspect that isotopes of the element could potentially be useful in medical imaging studies, especially astatine 211. The short life of this element makes it challenging to study, as it is difficult to get and it doesn't last long.
Naturally, the world's astatine is found in uranium ore. In a pure form, it appears to take on a solid state, and it seems to share many chemical properties with iodine, a closely related element. Researchers believe, for example, that astatine could accumulate in thyroid glands like iodine does. The element has an atomic number of 85, and it is identified on the periodic table of elements with the symbol At. It is the heaviest of the halogens.
The discovery of astatine was announced in 1931 by Fred Allison and E.J. Murphy. By 1940, a team of scientists in California had managed to create the 211 isotope; the credit for this discovery goes to D.R. Corson, K.R. Mackenzie, and Emilio Segré. The name of the element is derived from the Greek astatos, which means “unstable.”
Like other radioactive elements, astatine poses a human health risk. It can cause radiation damage to cells in people who are exposed to it without adequate protection. Fortunately, consumers do not generally need to worry about this danger because of its rarity, and in laboratories, the people who work with the element receive training in handling radioactive substances. Because it could collect in the thyroid gland, people who work with astatine are especially careful around it to ensure that they do not do long term damage to their bodies.