Melting point: degree Celsius, boiling point: degree Celsius. Astatine is highly toxic because of its high radioactivity. Electronegativity according to Pauling: 2. Mass number of astatine is , which is the most stable isotope of astatine.
It has covalent radius of pm and Van der Waals radius of pm. Astatine can react with hydrogen forming hydrogen astatide, which then forms hydroastatic acid when dissolved in water. Astatine forms complexes with a metal chelating agent, EDTA. Most of the isotopes of astatine are very unstable with one second or less half-lives. Astatine is known to bind with boron, carbon and nitrogen.
In benzene, astatine can replace atom of hydrogen, forming astatobenzene C 6 H 5 At , and then this can be oxidized by chlorine to C 6 H 5 AtCl 2. Astatine Uses. Astatine has an important role in nuclear medicine. Astatine is used for cancer treatment and as a radiotherapy only sometimes. Astatine is accumulated in the thyroid gland and liver in the similar way iodine is accumulated, but astatine does not emit electrons with high energy like iodine.
Only five of the isotopes even have half-lives longer than an hour. Isotope At 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 ; since that time less than two grams of the element have ever been produced.
This, together with its short lifetime, leaves no reason for considering the effects of astatine on human health. Astatine is studied in a few nuclear research laboratories where its high radioactivity requires special handling techniques and precautions.
Astatine is a halogen and possibly accumulates in the thyroid like iodine. From a chemical point of view, one can speculate that its toxicity would mimic that of iodine. Astatine does not occur to any significant extent in the biosphere and so normally never presents a risk. Twenty isotopes are known. Astatine possesses characteristics common to other halogens. It behaves most similarly to iodine, except that At exhibits more metallic properties.
The interhalogen molecules AtI, AtBr, and AtCl are known, although it has not been determined whether or not astatine forms diatomic At 2. HAt and CH 3 At have been detected. Astatine probably is capable of accumulating in the human thyroid gland. Sources : Astatine was first synthesized by Corson, MacKenzie, and Segre at the University of California in by bombarding bismuth with alpha particles. Astatine may be produced by bombarding bismuth with energetic alpha particles to produce At, At, and At These isotopes can be distilled from the target upon heating it in air.
Small quantities of At, At, and At occur naturally with uranium and thorium isotopes. Trace amounts of At exist in equilibrium with U and Np, resulting from the interaction between thorium and uranium with neutrons. The total amount of astatine present in the Earth's crust is less than 1 ounce. Uses : Similar to iodine, astatine may be used as a radioisotope in nuclear medicine, mainly for cancer treatment. The most useful isotope maybe astatine Although its half-life is only 7.
Astatine is more stable, but it decays into deadly polonium In animals, astatine is known to concentrate like iodine in the thyroid gland. Additionally, the element becomes concentrated in the lungs, spleen, and liver.
The element's use is controversial, as it has been shown to cause breast tissue changes in rodents. While researchers may safely handle trace quantities of astatine in well-ventilated fume hoods, working with the element is extremely dangerous. Element Classification : Halogen.
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