Where is the element astatine found

The Astatine atom has a covalent radius of In its elemental form, Astatine's CAS number is and its appearance is unknown. Astatine is the rarest naturally occurring non-transuranic element.

The amount of naturally occurring astatine in the world is about 25g. Astatine was discovered by Dale R. Astatine is highly radioactive.

Astatine information, including technical data, safety data, properties, research, applications and other useful facts are specified below. Scientific facts such as the atomic structure, ionization energy, abundance on Earth, conductivity and thermal properties are included. Astatine At has no stable isotopes. The 37 known isotopes of astatine, ranging from At to At, are radioactive. What's in a name? From the Greek word for unstable, astatos.

Say what? Astatine is pronounced as AS-teh-teen or as AS-teh-ten. Astatine was produced by Dale R. Horia Hulubei and Yvetter Cauchois, researchers at the Sorbonne in Paris, published the results of their discovery of element 85 in They used chemical separation and published that they found three X-ray spectral lines for the element that closely matched previous predictions. Unfortunately, the breakout of World War II disrupted their research as well as communications among scientists around the world.

The first successfully recognized discovery of astatine was in by Dale R. As no one had been able to find the rare element in nature, this group of scientists artificially produced it by bombarding bismuth with alpha particles in a particle accelerator. This reaction created astatine as well as two free neutrons.

The element was highly radioactive and unstable, which led to the name astatine from the Greek word that meant "unstable. Yet another group of researchers independently identified and characterized element 85 in the early s, according to Thornton and Burdette. Berta Karlik and Traude Bernert in reported the results of their studies, including the proposed name "viennium. Through a series of analyses the authors were able to identify the substance causing some of these radiations, with element 85 changing into polonium via K-electron capture.

Interestingly, in the article announcing their discovery, they also remarked about the possible existence of naturally occurring element 85 and cited the earlier work of Minder in Switzerland, as well as Hulubei and Cauchois in Paris, both of whom had claimed to have observed the element. They also mentioned the work carried out with Hamilton and Soley in which element 85 was concentrated into the thyroid glands of some guinea pigs, showing similar excretion to that of iodine, which occurs above element 85 in the periodic table.

Nevertheless, the chemical experiments of Corson et al. For example, element 85 precipitates as a sulfide and is precipitated by zinc in sulfuric acid, both of which are reactions that are characteristic of a metal rather than a nonmetal such as iodine. General Aspects of Astatine Element 85 has the dubious distinction of being one of very few solid elements that has never been obtained in any amount large enough to be visible to the naked eye.

It is also estimated that if a visible sample were ever produced, it would immediately vaporize away due to the heat generated by the emitted radioactivity. As a result of these properties the bulk behavior of astatine, such as its melting and boiling points, its color, and the degree to which it may be a metal can only be estimated theoretically.

Another controversy concerns the apparently simple question of whether diatomic molecules of At 2 occur as they do in the case of all the other halogens. The color is expected to be very dark and most probably black on the basis of the trend among the halogen group, to which astatine belongs.

This is because fluorine is almost colorless to yellow, chlorine is green, bromine brown, and iodine a violet color. In fact it is the single rarest naturally occurring element, with a total of just 1 oz. About thirty isotopes of the element have been synthesized or found to occur naturally, the longest-lived of which is At with a half-life of 8. Taken all together these facts about the element contribute to its almost complete lack of applications.

One exception has been an ongoing exploration of the potential uses of At in radiotherapy. Like the element above it in the periodic table, iodine, astatine has a tendency to be metabolized in the thyroid gland and could therefore be used to monitor medical conditions involving the thyroid and the throat area in general. But although these therapeutic potentially attractive properties have been explored for more than thirty-five years, problems concerning the safe delivery of At to human subjects, as well as issues relating to the ready production of the isotope, continue to delay the in vivo implementation of this rarest of all elements.

He has previously published two feature articles on the periodic table in Scientific American , which you can read here and here. Already a subscriber? Sign in. Thanks for reading Scientific American.