Astatine

A practical application for astatine as a cancer treatment would potentially be suitable for a "staggering" number of patients; production of astatine in the quantities that would be required remains an issue.

Contamination with astatine-210 is expected to be a drawback of this method. citation The most important isotope is astatine-211, the only one in commercial use.

Most of the organic chemistry of astatine is, however, analogous to that of iodine. citation Astatine has an electronegativity of 2.2 on the revised Pauling scale – lower than that of iodine (2.66) and the same as hydrogen.

Natural occurrence Neptunium series, showing the decay products, including astatine-217, formed from neptunium-237 Astatine is the rarest naturally occurring element.

Neither the most stable isotope astatine-210 nor the medically useful astatine-211 occurs naturally.

While astatine carriers that are slowly metabolized can be assessed for their efficacy, more rapidly metabolized carriers remain a significant obstacle to the evaluation of astatine in nuclear medicine.

With cryogenic technology, microgram quantities of astatine might be able to be generated via proton irradiation of thorium or uranium to yield radon-211, in turn decaying to astatine-211.

In their theoretical study, Ren's team examined a group of four of these materials: with one surface composed of either selenium or tellurium, and the other from either bromine or iodine—with both sides sandwiching a middle layer of astatine.

All its isotopes are short-lived; the most stable is astatine-210, with a half-life of 8.1 hours.

Astatine has no biological role.

Astatine is usually classified as either a nonmetal or a metalloid ; citation citation metal formation has also been predicted.

Astatine is very radioactive and thus highly dangerous.

Astatine's name comes from the Greek word astatos, meaning "unstable".

Astatine yields of up to around 80% may be achieved.

Atomic radii main Atomic number plotted against atomic radius The noble gases, astatine, francium, and all elements heavier than americium were left out as there is no data for them.

A total of 31 isotopes of astatine have been discovered, with atomic masses ranging from 193 to 223. Production Approximately six million metric tons of the fluorine mineral fluorite are produced each year.

Dry separation is the method most commonly used to produce a chemically useful form of astatine. citation citation Wet The bismuth (or sometimes bismuth trioxide ) target is dissolved in, for example, concentrated nitric or perchloric acid.

Elemental astatine has never been viewed because any macroscopic sample would be immediately vaporized by its radioactive heating.

Even though astatine is naturally occurring, it is usually produced by bombarding bismuth with alpha particles.

Four isotopes of astatine were subsequently found in nature, although it is the least abundant of all the naturally occurring elements, with much less than one gram being present at any given time in the Earth's crust.